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Find video protocols related to scientific articles indexed in Pubmed.
Book Review: "Regenerative Medicine Applications in Organ Transplantation"
Tissue Eng Part A
PUBLISHED: 10-31-2014
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Book Review.
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Live Fibroblast Harvest Reveals Surface Marker Shift in vitro.
Tissue Eng Part C Methods
PUBLISHED: 10-03-2014
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Current methods for the isolation of fibroblasts require extended ex vivo manipulation in cell culture. As a consequence, prior studies investigating fibroblast biology may fail to adequately represent cellular phenotypes in vivo. To overcome this problem, we describe a detailed protocol for the isolation of fibroblasts from the dorsal dermis of mice that bypasses the need for cell culture thereby preserving the physiologic transcriptional and proteomic profiles of each cell. Using the described protocol we characterized the transcriptional programs and the surface expression of 176 CD markers in cultured vs. uncultured fibroblasts. The differential expression patterns we observed highlight the importance of a live harvest for investigations of fibroblast biology.
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Noncontact, low-frequency ultrasound therapy enhances neovascularization and wound healing in diabetic mice.
Plast. Reconstr. Surg.
PUBLISHED: 08-28-2014
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Chronic wounds are a major source of morbidity for patients and represent a significant health burden. Implementing noninvasive techniques that accelerate healing of these wounds would provide great benefit. Ultrasound appears to be an effective modality for the treatment of chronic wounds in humans. MIST Therapy is a noncontact, low-frequency ultrasound treatment delivered through a saline mist. A variety of mechanisms have been proposed to explain the efficacy of ultrasound therapy, but the underlying molecular and cellular pathways impacted by this technique remain unclear. The in vivo effect of noncontact, low-frequency ultrasound was therefore examined in a humanized excisional wound model.
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Organ-level tissue engineering using bioreactor systems and stem cells: implications for transplant surgery.
Curr Stem Cell Res Ther
PUBLISHED: 07-30-2014
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Vascularized composite allotransplantation (VCA) enables surgeons to address complex problems that exceed the possibilities of traditional autologous reconstruction. However, logistical and immunologic challenges currently limit the widespread application of VCA. Recent breakthroughs in the field of stem cells and tissue engineering have direct implications for the advancement of VCA. Specifically, the use of bioreactors may prolong ex vivo allograft survival and enable allograft modulations that mitigate immunogenicity and enhance graft function. Additionally, novel approaches utilizing bioreactor systems for stem cell seeding of vascularized bioscaffolds provide a blueprint for the de novo generation of complex tissues. These promising bioreactor-based strategies have the potential to expand the reconstructive applications of VCA, and could one day allow the fabrication of customized complex tissue grafts.
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Studies in fat grafting: Part III. Fat grafting irradiated tissue--improved skin quality and decreased fat graft retention.
Plast. Reconstr. Surg.
PUBLISHED: 07-29-2014
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Following radiation therapy, skin becomes fibrotic and can present a difficult problem for reconstructive surgeons. There is an increasing belief that fat grafting under irradiated skin can reverse the damage caused by radiation. The present study evaluated the effect of fat grafting on irradiated skin, along with fat graft quality and retention rates in irradiated tissue.
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Capillary force seeding of hydrogels for adipose-derived stem cell delivery in wounds.
Stem Cells Transl Med
PUBLISHED: 07-18-2014
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Effective skin regeneration therapies require a successful interface between progenitor cells and biocompatible delivery systems. We previously demonstrated the efficiency of a biomimetic pullulan-collagen hydrogel scaffold for improving bone marrow-derived mesenchymal stem cell survival within ischemic skin wounds by creating a "stem cell niche" that enhances regenerative cytokine secretion. Adipose-derived mesenchymal stem cells (ASCs) represent an even more appealing source of stem cells because of their abundance and accessibility, and in this study we explored the utility of ASCs for hydrogel-based therapies. To optimize hydrogel cell seeding, a rapid, capillary force-based approach was developed and compared with previously established cell seeding methods. ASC viability and functionality following capillary hydrogel seeding were then analyzed in vitro and in vivo. In these experiments, ASCs were seeded more efficiently by capillary force than by traditional methods and remained viable and functional in this niche for up to 14 days. Additionally, hydrogel seeding of ASCs resulted in the enhanced expression of multiple stemness and angiogenesis-related genes, including Oct4, Vegf, Mcp-1, and Sdf-1. Moving in vivo, hydrogel delivery improved ASC survival, and application of both murine and human ASC-seeded hydrogels to splinted murine wounds resulted in accelerated wound closure and increased vascularity when compared with control wounds treated with unseeded hydrogels. In conclusion, capillary seeding of ASCs within a pullulan-collagen hydrogel bioscaffold provides a convenient and simple way to deliver therapeutic cells to wound environments. Moreover, ASC-seeded constructs display a significant potential to accelerate wound healing that can be easily translated to a clinical setting.
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Studies in fat grafting: Part II. Effects of injection mechanics on material properties of fat.
Plast. Reconstr. Surg.
PUBLISHED: 07-17-2014
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Although fat grafting can address many soft-tissue deficits, results remain inconsistent. In this study, the authors compared physical properties of fat following injection using an automated, low-shear device or the modified Coleman technique.
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Transcriptional profiling of rapamycin-treated fibroblasts from hypertrophic and keloid scars.
Ann Plast Surg
PUBLISHED: 05-20-2014
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Excess scar formation after cutaneous injury can result in hypertrophic scar (HTS) or keloid formation. Modern strategies to treat pathologic scarring represent nontargeted approaches that produce suboptimal results. Mammalian target of rapamycin (mTOR), a central mediator of inflammation, has been proposed as a novel target to block fibroproliferation. To examine its mechanism of action, we performed genomewide microarray on human fibroblasts (from normal skin, HTS, and keloid scars) treated with the mTOR inhibitor, rapamycin. Hypertrophic scar and keloid fibroblasts demonstrated overexpression of collagen I and III that was effectively abrogated with rapamycin. Blockade of mTOR specifically impaired fibroblast expression of the collagen biosynthesis genes PLOD, PCOLCE, and P4HA, targets significantly overexpressed in HTS and keloid scars. These data suggest that pathologic scarring can be abrogated via modulation of mTOR pathways in procollagen and collagen processing.
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A randomized controlled trial of the embrace advanced scar therapy device to reduce incisional scar formation.
Plast. Reconstr. Surg.
PUBLISHED: 05-09-2014
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Scarring represents a significant biomedical burden in clinical medicine. Mechanomodulation has been linked to scarring through inflammation, but until now a systematic approach to attenuate mechanical force and reduce scarring has not been possible.
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Diabetes irreversibly depletes bone marrow-derived mesenchymal progenitor cell subpopulations.
Diabetes
PUBLISHED: 04-16-2014
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Diabetic vascular pathology is largely attributable to impairments in tissue recovery from hypoxia. Circulating progenitor cells have been postulated to play a role in ischemic recovery, and deficiencies in these cells have been well described in diabetic patients. Here, we examine bone marrow-derived mesenchymal progenitor cells (BM-MPCs) that have previously been shown to be important for new blood vessel formation and demonstrate significant deficits in the context of diabetes. Further, we determine that this dysfunction is attributable to intrinsic defects in diabetic BM-MPCs that are not correctable by restoring glucose homeostasis. We identify two transcriptionally distinct subpopulations that are selectively depleted by both type 1 and type 2 diabetes, and these subpopulations have provasculogenic expression profiles, suggesting that they are vascular progenitor cells. These results suggest that the clinically observed deficits in progenitor cells may be attributable to selective and irreversible depletion of progenitor cell subsets in patients with diabetes.
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Mechanical offloading of incisional wounds is associated with transcriptional downregulation of inflammatory pathways in a large animal model.
Organogenesis
PUBLISHED: 04-16-2014
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Cutaneous scarring is a major source of morbidity and current therapies to mitigate scar formation remain ineffective. Although wound fibrosis and inflammation are highly linked, only recently have mechanical forces been implicated in these pathways. Our group has developed a topical polymer device that significantly reduces post-injury scar formation via the manipulation of mechanical forces. Here we extend these studies to examine the genomewide transcriptional effects of mechanomodulation during scar formation using a validated large animal model, the red Duroc pig. We demonstrate that mechanical loading of incisional wounds upregulates expression of genes associated with inflammatory and fibrotic pathways, and that device-mediated offloading of these wounds reverses these effects. Validation studies are needed to clarify the clinical significance of these findings.
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The role of stem cells in aesthetic surgery: fact or fiction?
Plast. Reconstr. Surg.
PUBLISHED: 04-16-2014
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Stem cells are attractive candidates for the development of novel therapies, targeting indications that involve functional restoration of defective tissue. Although most stem cell therapies are new and highly experimental, there are clinics around the world that exploit vulnerable patients with the hope of offering supposed stem cell therapies, many of which operate without credible scientific merit, oversight, or other patient protection.
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Cell recruitment by amnion chorion grafts promotes neovascularization.
J. Surg. Res.
PUBLISHED: 04-07-2014
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Nonhealing wounds are a significant health burden. Stem and progenitor cells can accelerate wound repair and regeneration. Human amniotic membrane has demonstrated efficacy in promoting wound healing, though the underlying mechanisms remain unknown. A dehydrated human amnion chorion membrane (dHACM) was tested for its ability to recruit hematopoietic progenitor cells to a surgically implanted graft in a murine model of cutaneous ischemia.
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The Stanford Microsurgery and Resident Training (SMaRT) Scale: validation of an on-line global rating scale for technical assessment.
Ann Plast Surg
PUBLISHED: 04-03-2014
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We previously reported results of our on-line microsurgery training program, showing that residents who had access to our website significantly improved their cognitive and technical skills. In this study, we report an objective means for expert evaluators to reliably rate trainees' technical skills under the microscope, with the use of our novel global rating scale.
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Studies in fat grafting: Part I. Effects of injection technique on in vitro fat viability and in vivo volume retention.
Plast. Reconstr. Surg.
PUBLISHED: 03-14-2014
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Fat grafting has become increasingly popular for the correction of soft-tissue deficits at many sites throughout the body. Long-term outcomes, however, depend on delivery of fat in the least traumatic fashion to optimize viability of the transplanted tissue. In this study, the authors compare the biological properties of fat following injection using two methods.
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Diabetes impairs the angiogenic potential of adipose-derived stem cells by selectively depleting cellular subpopulations.
Stem Cell Res Ther
PUBLISHED: 02-17-2014
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Pathophysiologic changes associated with diabetes impair new blood vessel formation and wound healing. Mesenchymal stem cells derived from adipose tissue (ASCs) have been used clinically to promote healing, although it remains unclear whether diabetes impairs their functional and therapeutic capacity.
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Gene expression in fetal murine keratinocytes and fibroblasts.
J. Surg. Res.
PUBLISHED: 02-17-2014
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Early fetuses heal wounds without the formation of a scar. Many studies have attempted to explain this remarkable phenomenon. However, the exact mechanism remains unknown. Herein, we examine the predominant cell types of the epidermis and dermis--the keratinocyte and fibroblast--during different stages of fetal development to better understand the changes that lead to scarring wound repair versus regeneration.
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The Role of Hypoxia-Inducible Factor in Wound Healing.
Adv Wound Care (New Rochelle)
PUBLISHED: 01-30-2014
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Significance: Poor wound healing remains a significant health issue for a large number of patients in the United States. The physiologic response to local wound hypoxia plays a critical role in determining the success of the normal healing process. Hypoxia-inducible factor-1 (HIF-1), as the master regulator of oxygen homeostasis, is an important determinant of healing outcomes. HIF-1 contributes to all stages of wound healing through its role in cell migration, cell survival under hypoxic conditions, cell division, growth factor release, and matrix synthesis throughout the healing process. Recent Advances: Positive regulators of HIF-1, such as prolyl-4-hydroxylase inhibitors, have been shown to be beneficial in enhancing diabetic ischemic wound closure and are currently undergoing clinical trials for treatment of several human-ischemia-based conditions. Critical Issues: HIF-1 deficiency and subsequent failure to respond to hypoxic stimuli leads to chronic hypoxia, which has been shown to contribute to the formation of nonhealing ulcers. In contrast, overexpression of HIF-1 has been implicated in fibrotic disease through its role in increasing myofibroblast differentiation leading to excessive matrix production and deposition. Both positive and negative regulators of HIF-1 therefore provide important therapeutic targets that can be used to manipulate HIF-1 expression where an excess or deficiency in HIF-1 is known to correlate with pathogenesis. Future Directions: Targeting HIF-1 during wound healing has many important clinical implications for tissue repair. Counteracting the detrimental effects of excessive or deficient HIF-1 signaling by modulating HIF-1 expression may improve future management of poorly healing wounds.
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Reduced BMPR2 expression induces GM-CSF translation and macrophage recruitment in humans and mice to exacerbate pulmonary hypertension.
J. Exp. Med.
PUBLISHED: 01-20-2014
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Idiopathic pulmonary arterial hypertension (PAH [IPAH]) is an insidious and potentially fatal disease linked to a mutation or reduced expression of bone morphogenetic protein receptor 2 (BMPR2). Because intravascular inflammatory cells are recruited in IPAH pathogenesis, we hypothesized that reduced BMPR2 enhances production of the potent chemokine granulocyte macrophage colony-stimulating factor (GM-CSF) in response to an inflammatory perturbation. When human pulmonary artery (PA) endothelial cells deficient in BMPR2 were stimulated with tumor necrosis factor (TNF), a twofold increase in GM-CSF was observed and related to enhanced messenger RNA (mRNA) translation. The mechanism was associated with disruption of stress granule formation. Specifically, loss of BMPR2 induced prolonged phospho-p38 mitogen-activated protein kinase (MAPK) in response to TNF, and this increased GADD34-PP1 phosphatase activity, dephosphorylating eukaryotic translation initiation factor (eIF2?), and derepressing GM-CSF mRNA translation. Lungs from IPAH patients versus unused donor controls revealed heightened PA expression of GM-CSF co-distributing with increased TNF and expanded populations of hematopoietic and endothelial GM-CSF receptor ? (GM-CSFR?)-positive cells. Moreover, a 3-wk infusion of GM-CSF in mice increased hypoxia-induced PAH, in association with increased perivascular macrophages and muscularized distal arteries, whereas blockade of GM-CSF repressed these features. Thus, reduced BMPR2 can subvert a stress granule response, heighten GM-CSF mRNA translation, increase inflammatory cell recruitment, and exacerbate PAH.
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Mechanotransduction and fibrosis.
J Biomech
PUBLISHED: 01-15-2014
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Scarring and tissue fibrosis represent a significant source of morbidity in the United States. Despite considerable research focused on elucidating the mechanisms underlying cutaneous scar formation, effective clinical therapies are still in the early stages of development. A thorough understanding of the various signaling pathways involved is essential to formulate strategies to combat fibrosis and scarring. While initial efforts focused primarily on the biochemical mechanisms involved in scar formation, more recent research has revealed a central role for mechanical forces in modulating these pathways. Mechanotransduction, which refers to the mechanisms by which mechanical forces are converted to biochemical stimuli, has been closely linked to inflammation and fibrosis and is believed to play a critical role in scarring. This review provides an overview of our current understanding of the mechanisms underlying scar formation, with an emphasis on the relationship between mechanotransduction pathways and their therapeutic implications.
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Poly-L-arginine topical lotion tested in a mouse model for frostbite injury.
Wilderness Environ Med
PUBLISHED: 01-11-2014
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Frostbite injury occurs when exposure to cold results in frozen tissue. We recently reported a novel mouse model for frostbite injury to be used in screening potentially therapeutic drugs and other modalities.
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A histological and mechanical analysis of the cardiac lead-tissue interface: implications for lead extraction.
Acta Biomater
PUBLISHED: 01-07-2014
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The major risks of pacemaker and implantable cardioverter defibrillator extraction are attributable to the fibrotic tissue that encases them in situ, yet little is known about the cellular and functional properties of this response. In the present research, we performed a histological and mechanical analysis of human tissue collected from the lead-tissue interface to better understand this process and provide insights for the improvement of lead design and extraction. The lead-tissue interface consisted of a thin cellular layer underlying a smooth, acellular surface, followed by a circumferentially organized collagen-rich matrix. 51.8±4.9% of cells were myofibroblasts via immunohistochemistry, with these cells displaying a similar circumferential organization. Upon mechanical testing, samples exhibited a triphasic force-displacement response consisting of a toe region during initial tensioning, a linear elastic region and a yield and failure region. Mean fracture load was 5.6±2.1N, and mean circumferential stress at failure was 9.5±4.1MPa. While the low cellularity and fibrotic composition of tissue observed herein is consistent with a foreign body reaction to an implanted material, the significant myofibroblast response provides a mechanical explanation for the contractile forces complicating extractions. Moreover, the tensile properties of this tissue suggest the feasibility of circumferential mechanical tissue disruption, similar to balloon angioplasty devices, as a novel approach to assist with lead extraction.
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Tracking the elusive fibrocyte: identification and characterization of collagen-producing hematopoietic lineage cells during murine wound healing.
Stem Cells
PUBLISHED: 01-02-2014
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Fibrocytes are a unique population of circulating cells reported to exhibit characteristics of both hematopoietic and mesenchymal cells, and play an important role in wound healing. However, putative fibrocytes have been found to lose expression of hematopoietic surface markers such as CD45 during differentiation, making it difficult to track these cells in vivo with conventional methodologies. In this study, to distinguish hematopoietic and nonhematopoietic cells without surface markers, we took advantage of the gene vav 1, which is expressed solely on hematopoietic cells but not on other cell types, and established a novel transgenic mouse, in which hematopoietic cells are irreversibly labeled with green fluorescent protein and nonhematopoietic cells with red fluorescent protein. Use of single-cell transcriptional analysis in this mouse model revealed two discrete types of collagen I (Col I) expressing cells of hematopoietic lineage recruited into excisional skin wounds. We confirmed this finding on a protein level, with one subset of these Col I synthesizing cells being CD45+ and CD11b+, consistent with the traditional definition of a fibrocyte, while another was CD45- and Cd11b-, representing a previously unidentified population. Both cell types were found to initially peak, then reduce posthealing, consistent with a disappearance from the wound site and not a loss of identifying surface marker expression. Taken together, we have unambiguously identified two cells of hematopoietic origin that are recruited to the wound site and deposit collagen, definitively confirming the existence and natural time course of fibrocytes in cutaneous healing.
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Angiogenic properties of dehydrated human amnion/chorion allografts: therapeutic potential for soft tissue repair and regeneration.
PUBLISHED: 01-01-2014
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Chronic wounds are associated with a number of deficiencies in critical wound healing processes, including growth factor signaling and neovascularization. Human-derived placental tissues are rich in regenerative cytokines and have been shown in randomized clinical trials to be effective for healing chronic wounds. In this study, PURION® Processed (MiMedx Group, Marietta, GA) dehydrated human amnion/chorion membrane tissue allografts (dHACM, EpiFix®, MiMedx) were evaluated for properties to support wound angiogenesis.
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Epidermal or dermal specific knockout of PHD-2 enhances wound healing and minimizes ischemic injury.
PLoS ONE
PUBLISHED: 01-01-2014
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Hypoxia-inducible factor (HIF)-1?, part of the heterodimeric transcription factor that mediates the cellular response to hypoxia, is critical for the expression of multiple angiogenic growth factors, cell motility, and the recruitment of endothelial progenitor cells. Inhibition of the oxygen-dependent negative regulator of HIF-1?, prolyl hydroxylase domain-2 (PHD-2), leads to increased HIF-1? and mimics various cellular and physiological responses to hypoxia. The roles of PHD-2 in the epidermis and dermis have not been clearly defined in wound healing.
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From germ theory to germ therapy: skin microbiota, chronic wounds, and probiotics.
Plast. Reconstr. Surg.
PUBLISHED: 10-30-2013
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Microorganisms living throughout the body comprise the human "microbiota" and play an important role in health and disease. Recent research suggests that alterations in the skin microbiota may underlie chronic wound pathology. Probiotics are bacteria or yeast that confer a health benefit on the host and may have a role in preventing and treating nonhealing wounds by modulating host-microbe interactions.
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Biological therapies for the treatment of cutaneous wounds: phase III and launched therapies.
Expert Opin Biol Ther
PUBLISHED: 10-05-2013
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Normal wound healing mechanisms can be overwhelmed in the setting of complex acute and chronic tissue injury. Biological therapies are designed to augment and/or restore the bodys natural wound healing abilities. There are a variety of available and emerging technologies utilizing this approach that have demonstrated the ability to augment wound healing.
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Nipple Reconstruction: Risk Factors and Complications after 189 Procedures.
Eur J Plast Surg
PUBLISHED: 09-28-2013
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A multitude of different approaches have been proposed for achieving optimal aesthetic results after nipple reconstruction. In contrast, however, only a few studies focus on the morbidity associated with this procedure, particularly after implant-based breast reconstruction.
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Murine models of human wound healing.
Methods Mol. Biol.
PUBLISHED: 09-14-2013
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In vivo wound healing experiments remain the most predictive models for studying human wound healing, allowing an accurate representation of the complete wound healing environment including various cell types, environmental cues, and paracrine interactions. Small animals are economical, easy to maintain, and allow researchers to take advantage of the numerous transgenic strains that have been developed to investigate the specific mechanisms involved in wound healing and regeneration. Here we describe three reproducible murine wound healing models that recapitulate the human wound healing process.
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Adult stem cells in small animal wound healing models.
Methods Mol. Biol.
PUBLISHED: 09-14-2013
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This chapter broadly reviews the use of stem cells as a means to accelerate wound healing, focusing first on the properties of stem cells that make them attractive agents to influence repair, both alone and as vehicles for growth factor delivery. Major stem cell reservoirs are described, including adult, embryonic, and induced pluripotent cell sources, outlining the advantages and limitations of each source as wound healing agents, as well as the possible mechanisms responsible for wound healing acceleration. Finally, the chapter includes a materials and methods section that provides an in-depth description of adult tissue harvest techniques.
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Isolation of human adipose-derived stromal cells using laser-assisted liposuction and their therapeutic potential in regenerative medicine.
Stem Cells Transl Med
PUBLISHED: 09-09-2013
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Harvesting adipose-derived stromal cells (ASCs) for tissue engineering is frequently done through liposuction. However, several different techniques exist. Although third-generation ultrasound-assisted liposuction has been shown to not have a negative effect on ASCs, the impact of laser-assisted liposuction on the quality and differentiation potential of ASCs has not been studied. Therefore, ASCs were harvested from laser-assisted lipoaspirate and suction-assisted lipoaspirate. Next, in vitro parameters of cell yield, cell viability and proliferation, surface marker phenotype, osteogenic differentiation, and adipogenic differentiation were performed. Finally, in vivo bone formation was assessed using a critical-sized cranial defect in athymic nude mice. Although ASCs isolated from suction-assisted lipoaspirate and laser-assisted lipoaspirate both successfully underwent osteogenic and adipogenic differentiation, the cell yield, viability, proliferation, and frequency of ASCs (CD34(+)CD31(-)CD45(-)) in the stromal vascular fraction were all significantly less with laser-assisted liposuction in vitro (p < .05). In vivo, quantification of osseous healing by micro-computed tomography revealed significantly more healing with ASCs isolated from suction-assisted lipoaspirate relative to laser-assisted lipoaspirate at the 4-, 6-, and 8-week time points (p < .05). Therefore, as laser-assisted liposuction appears to negatively impact the biology of ASCs, cell harvest using suction-assisted liposuction is preferable for tissue-engineering purposes.
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Molecular analysis and differentiation capacity of adipose-derived stem cells from lymphedema tissue.
Plast. Reconstr. Surg.
PUBLISHED: 08-30-2013
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Many breast cancer patients are plagued by the disabling complication of upper limb lymphedema after axillary surgery. Conservative treatments using massage and compression therapy do not offer a lasting relief, as they fail to address the chronic transformation of edema into excess adipose tissue. Liposuction to address the adipose nature of the lymphedema has provided an opportunity for a detailed analysis of the stromal fraction of lymphedema-associated fat to clarify the molecular mechanisms for this adipogenic transformation.
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Biological properties of dehydrated human amnion/chorion composite graft: implications for chronic wound healing.
Int Wound J
PUBLISHED: 08-01-2013
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Human amnion/chorion tissue derived from the placenta is rich in cytokines and growth factors known to promote wound healing; however, preservation of the biological activities of therapeutic allografts during processing remains a challenge. In this study, PURION® (MiMedx, Marietta, GA) processed dehydrated human amnion/chorion tissue allografts (dHACM, EpiFix®, MiMedx) were evaluated for the presence of growth factors, interleukins (ILs) and tissue inhibitors of metalloproteinases (TIMPs). Enzyme-linked immunosorbent assays (ELISA) were performed on samples of dHACM and showed quantifiable levels of the following growth factors: platelet-derived growth factor-AA (PDGF-AA), PDGF-BB, transforming growth factor ? (TGF?), TGF?1, basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), placental growth factor (PLGF) and granulocyte colony-stimulating factor (GCSF). The ELISA assays also confirmed the presence of IL-4, 6, 8 and 10, and TIMP 1, 2 and 4. Moreover, the relative elution of growth factors into saline from the allograft ranged from 4% to 62%, indicating that there are bound and unbound fractions of these compounds within the allograft. dHACM retained biological activities that cause human dermal fibroblast proliferation and migration of human mesenchymal stem cells (MSCs) in vitro. An in vivo mouse model showed that dHACM when tested in a skin flap model caused mesenchymal progenitor cell recruitment to the site of implantation. The results from both the in vitro and in vivo experiments clearly established that dHACM contains one or more soluble factors capable of stimulating MSC migration and recruitment. In summary, PURION® processed dHACM retains its biological activities related to wound healing, including the potential to positively affect four distinct and pivotal physiological processes intimately involved in wound healing: cell proliferation, inflammation, metalloproteinase activity and recruitment of progenitor cells. This suggests a paracrine mechanism of action for dHACM when used for wound healing applications.
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Cellular response to a novel fetal acellular collagen matrix: implications for tissue regeneration.
Int J Biomater
PUBLISHED: 04-18-2013
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Introduction. PriMatrix (TEI Biosciences Inc., Boston, MA, USA) is a novel acellular collagen matrix derived from fetal bovine dermis that is designed for use in partial- and full-thickness wounds. This study analyzes the cellular response to PriMatrix in vivo, as well as the ability of this matrix to facilitate normal tissue regeneration. Methods. Five by five?mm squares of rehydrated PriMatrix were implanted in a subcutaneous fashion on the dorsum of wild-type mice. Implant site tissue was harvested for histology, immunohistochemistry (IHC), and flow cytometric analyses at multiple time points until day 28. Results. PriMatrix implants were found to go through a biological progression initiated by a transient infiltrate of inflammatory cells, followed by mesenchymal cell recruitment and vascular development. IHC analysis revealed that the majority of the implanted fetal dermal collagen fibers persisted through day 28 but underwent remodeling and cellular repopulation to form tissue with a density and morphology consistent with healthy dermis. Conclusions. PriMatrix implants undergo progressive in vivo remodeling, facilitating the regeneration of histologically normal tissue through a mild inflammatory and progenitor cell response. Regeneration of normal tissue is especially important in a wound environment, and these findings warrant further investigation of PriMatrix in this setting.
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Nipple reconstruction after implant-based breast reconstruction: a "matched-pair" outcome analysis focusing on the effects of radiotherapy.
J Plast Reconstr Aesthet Surg
PUBLISHED: 04-06-2013
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The major focus of research when addressing nipple reconstruction has been on developing new techniques to provide for long-lasting nipple projection. Rarely, has the outcome of nipple reconstruction as it relates to postoperative morbidity, particularly after implant-based breast reconstruction, been analyzed.
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Direct contact of fibroblasts with neuronal processes promotes differentiation to myofibroblasts and induces contraction of collagen matrix in vitro.
Wound Repair Regen
PUBLISHED: 03-18-2013
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Wound healing is often delayed in the patients whose sensory and autonomic innervation is impaired. We hypothesized that existence of neurites in the skin may promote wound healing by inducing differentiation of fibroblasts into myofibroblasts with consequent wound contraction. In the current study, we examined the effect of neurons on differentiation of fibroblasts and contraction of collagen matrix in vitro using a new co-culture model. Neuronal cell line, PC12 cells, of which the neurite outgrowth can be controlled by adding nerve growth factor, was used. Rat dermal fibroblasts were co-cultured with PC12 cells extending neurites or with PC12 cells lacking neurites. Then, differentiation of fibroblasts into myofibroblasts and contraction of the collagen matrix was evaluated. Finally, we examined whether direct or indirect contact with neurites of PC12 cells promoted the differentiation of fibroblasts. Our results showed that fibroblasts co-cultured with PC12 extending neurites differentiated into myofibroblasts more effectively and contracted the collagen matrix stronger than those with PC12 lacking neurites. Direct contact of fibroblasts with neurites promoted more differentiation than indirect contact. In conclusion, direct contact of fibroblasts with neuronal processes is important for differentiation into myofibroblasts and induction of collagen gel contraction, leading to promotion of wound healing.
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Intraoperative imaging of nipple perfusion patterns and ischemic complications in nipple-sparing mastectomies.
Ann. Surg. Oncol.
PUBLISHED: 03-06-2013
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Nipple-sparing mastectomies (NSM) have gained acceptance in the field of breast oncology. Ischemic complications involving the nipple-areolar complex (NAC) occur in 3-37 % of cases. Skin perfusion can be monitored intraoperatively using indocyanine green (IC-GREEN™, ICG) and a specialized infrared camera-computer system (SPY Elite™). The blood flow pattern to the breast skin and the NAC were evaluated and a classification scheme was developed.
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A novel mouse model for frostbite injury.
Wilderness Environ Med
PUBLISHED: 03-06-2013
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Frostbite injury occurs when exposure to cold results in frozen tissue. To screen drugs and other field therapies that might improve the outcome for a frostbite victim, it would be helpful to have a reliable and cost-effective preclinical in vivo model.
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Wound healing: a paradigm for regeneration.
Mayo Clin. Proc.
PUBLISHED: 02-20-2013
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Human skin is a remarkably plastic organ that sustains insult and injury throughout life. Its ability to expeditiously repair wounds is paramount to survival and is thought to be regulated by wound components such as differentiated cells, stem cells, cytokine networks, extracellular matrix, and mechanical forces. These intrinsic regenerative pathways are integrated across different skin compartments and are being elucidated on the cellular and molecular levels. Recent advances in bioengineering and nanotechnology have allowed researchers to manipulate these microenvironments in increasingly precise spatial and temporal scales, recapitulating key homeostatic cues that may drive regeneration. The ultimate goal is to translate these bench achievements into viable bedside therapies that address the growing global burden of acute and chronic wounds. In this review, we highlight current concepts in cutaneous wound repair and propose that many of these evolving paradigms may underlie regenerative processes across diverse organ systems.
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Evidence that mast cells are not required for healing of splinted cutaneous excisional wounds in mice.
PLoS ONE
PUBLISHED: 02-13-2013
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Wound healing is a complex biological process involving the interaction of many cell types to replace lost or damaged tissue. Although the biology of wound healing has been extensively investigated, few studies have focused on the role of mast cells. In this study, we investigated the possible role of mast cells in wound healing by analyzing aspects of cutaneous excisional wound healing in three types of genetically mast cell-deficient mice. We found that C57BL/6-Kit(W-sh/W-sh), WBB6F1-Kit(W/W-v), and Cpa3-Cre; Mcl-1(fl/fl) mice re-epithelialized splinted excisional skin wounds at rates very similar to those in the corresponding wild type or control mice. Furthermore, at the time of closure, scars were similar in the genetically mast cell-deficient mice and the corresponding wild type or control mice in both quantity of collagen deposition and maturity of collagen fibers, as evaluated by Massons Trichrome and Picro-Sirius red staining. These data indicate that mast cells do not play a significant non-redundant role in these features of the healing of splinted full thickness excisional cutaneous wounds in mice.
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The role of focal adhesion complexes in fibroblast mechanotransduction during scar formation.
Differentiation
PUBLISHED: 01-23-2013
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Historically, great efforts have been made to elucidate the biochemical pathways that direct the complex process of wound healing; however only recently has there been recognition of the importance that mechanical signals play in the process of tissue repair and scar formation. The bodys physiologic response to injury involves a dynamic interplay between mechanical forces and biochemical cues which directs a cascade of signals leading ultimately to the formation of fibrotic scar. Fibroblasts are a highly mechanosensitive cell type and are also largely responsible for the generation of the fibrotic matrix during scar formation and are thus a critical player in the process of mechanotransduction during tissue repair. Mechanotransduction is initiated at the interface between the cell membrane and the extracellular matrix where mechanical signals are first translated into a biochemical response. Focal adhesions are dynamic multi-protein complexes through which the extracellular matrix links to the intracellular cytoskeleton. These focal adhesion complexes play an integral role in the propagation of this initial mechanical cue into an extensive network of biochemical signals leading to widespread downstream effects including the influx of inflammatory cells, stimulation of angiogenesis, keratinocyte migration, fibroblast proliferation and collagen synthesis. Increasing evidence has demonstrated the importance of the biomechanical milieu in healing wounds and suggests that an integrated approach to the discovery of targets to decrease scar formation may prove more clinically efficacious than previous purely biochemical strategies.
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Intraoperative laser angiography using the SPY system: review of the literature and recommendations for use.
Ann Surg Innov Res
PUBLISHED: 01-07-2013
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Inadequate tissue perfusion is a key contributor to early complications following reconstructive procedures. Accurate and reliable intraoperative evaluation of tissue perfusion is critical to reduce complications and improve clinical outcomes. Clinical judgment is the most commonly used method for evaluating blood supply, but when used alone, is not always completely reliable. A variety of other methodologies have been evaluated, including Doppler devices, tissue oximetry, and fluorescein, among others. However, none have achieved widespread acceptance. Recently, intraoperative laser angiography using indocyanine green was introduced to reconstructive surgery. This vascular imaging technology provides real-time assessment of tissue perfusion that correlates with clinical outcomes and can be used to guide surgical decision making. Although this technology has been used for decades in other areas, surgeons may not be aware of its utility for perfusion assessment in reconstructive surgery. A group of experts with extensive experience with intraoperative laser angiography convened to identify key issues in perfusion assessment, review available methodologies, and produce initial recommendations for the use of this technology in reconstructive procedures.
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Nonintegrating knockdown and customized scaffold design enhances human adipose-derived stem cells in skeletal repair.
Stem Cells
PUBLISHED: 10-15-2011
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An urgent need exists in clinical medicine for suitable alternatives to available techniques for bone tissue repair. Human adipose-derived stem cells (hASCs) represent a readily available, autogenous cell source with well-documented in vivo osteogenic potential. In this article, we manipulated Noggin expression levels in hASCs using lentiviral and nonintegrating minicircle short hairpin ribonucleic acid (shRNA) methodologies in vitro and in vivo to enhance hASC osteogenesis. Human ASCs with Noggin knockdown showed significantly increased bone morphogenetic protein (BMP) signaling and osteogenic differentiation both in vitro and in vivo, and when placed onto a BMP-releasing scaffold embedded with lentiviral Noggin shRNA particles, hASCs more rapidly healed mouse calvarial defects. This study therefore suggests that genetic targeting of hASCs combined with custom scaffold design can optimize hASCs for skeletal regenerative medicine.
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CD105 protein depletion enhances human adipose-derived stromal cell osteogenesis through reduction of transforming growth factor ?1 (TGF-?1) signaling.
J. Biol. Chem.
PUBLISHED: 09-23-2011
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Clinically available sources of bone for repair and reconstruction are limited by the accessibility of autologous grafts, infectious risks of cadaveric materials, and durability of synthetic substitutes. Cell-based approaches for skeletal regeneration can potentially fill this need, and adipose tissue represents a promising source for development of such therapies. Here, we enriched for an osteogenic subpopulation of cells derived from human subcutaneous adipose tissue utilizing microfluidic-based single cell transcriptional analysis and fluorescence-activated cell sorting (FACS). Statistical analysis of single cell transcriptional profiles demonstrated that low expression of endoglin (CD105) correlated with a subgroup of adipose-derived cells with increased osteogenic gene expression. FACS-sorted CD105(low) cells demonstrated significantly enhanced in vitro osteogenic differentiation and in vivo bone regeneration when compared with either CD105(high) or unsorted cells. Evaluation of the endoglin pathway suggested that enhanced osteogenesis among CD105(low) adipose-derived cells is likely due to identification of a subpopulation with lower TGF-?1/Smad2 signaling. These findings thus highlight a potential avenue to promote osteogenesis in adipose-derived mesenchymal cells for skeletal regeneration.
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Mechanical force prolongs acute inflammation via T-cell-dependent pathways during scar formation.
FASEB J.
PUBLISHED: 09-12-2011
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Mechanical force significantly modulates both inflammation and fibrosis, yet the fundamental mechanisms that regulate these interactions remain poorly understood. Here we performed microarray analysis to compare gene expression in mechanically loaded wounds vs. unloaded control wounds in an established murine hypertrophic scar (HTS) model. We identified 853 mechanically regulated genes (false discovery rate <2) at d 14 postinjury, a subset of which were enriched for T-cell-regulated pathways. To substantiate the role of T cells in scar mechanotransduction, we applied the HTS model to T-cell-deficient mice and wild-type mice. We found that scar formation in T-cell-deficient mice was reduced by almost 9-fold (P < 0.001) with attenuated epidermal (by 2.6-fold, P < 0.01) and dermal (3.9-fold, P < 0.05) proliferation. Mechanical stimulation was highly associated with sustained T-cell-dependent Th2 cytokine (IL-4 and IL-13) and chemokine (MCP-1) signaling. Further, T-cell-deficient mice failed to recruit systemic inflammatory cells such as macrophages or monocytic fibroblast precursors in response to mechanical loading. These findings indicate that T-cell-regulated fibrogenic pathways are highly mechanoresponsive and suggest that mechanical forces induce a chronic-like inflammatory state through immune-dependent activation of both local and systemic cell populations.
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Focal adhesion kinase links mechanical force to skin fibrosis via inflammatory signaling.
Nat. Med.
PUBLISHED: 08-26-2011
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Exuberant fibroproliferation is a common complication after injury for reasons that are not well understood. One key component of wound repair that is often overlooked is mechanical force, which regulates cell-matrix interactions through intracellular focal adhesion components, including focal adhesion kinase (FAK). Here we report that FAK is activated after cutaneous injury and that this process is potentiated by mechanical loading. Fibroblast-specific FAK knockout mice have substantially less inflammation and fibrosis than control mice in a model of hypertrophic scar formation. We show that FAK acts through extracellular-related kinase (ERK) to mechanically trigger the secretion of monocyte chemoattractant protein-1 (MCP-1, also known as CCL2), a potent chemokine that is linked to human fibrotic disorders. Similarly, MCP-1 knockout mice form minimal scars, indicating that inflammatory chemokine pathways are a major mechanism by which FAK mechanotransduction induces fibrosis. Small-molecule inhibition of FAK blocks these effects in human cells and reduces scar formation in vivo through attenuated MCP-1 signaling and inflammatory cell recruitment. These findings collectively indicate that physical force regulates fibrosis through inflammatory FAK-ERK-MCP-1 pathways and that molecular strategies targeting FAK can effectively uncouple mechanical force from pathologic scar formation.
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Enhancement of mesenchymal stem cell angiogenic capacity and stemness by a biomimetic hydrogel scaffold.
Biomaterials
PUBLISHED: 08-25-2011
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In this study, we examined the capacity of a biomimetic pullulan-collagen hydrogel to create a functional biomaterial-based stem cell niche for the delivery of mesenchymal stem cells (MSCs) into wounds. Murine bone marrow-derived MSCs were seeded into hydrogels and compared to MSCs grown in standard culture conditions. Hydrogels induced MSC secretion of angiogenic cytokines and expression of transcription factors associated with maintenance of pluripotency and self-renewal (Oct4, Sox2, Klf4) when compared to MSCs grown in standard conditions. An excisonal wound healing model was used to compare the ability of MSC-hydrogel constructs versus MSC injection alone to accelerate wound healing. Injection of MSCs did not significantly improve time to wound closure. In contrast, wounds treated with MSC-seeded hydrogels showed significantly accelerated healing and a return of skin appendages. Bioluminescence imaging and FACS analysis of luciferase+/GFP+ MSCs indicated that stem cells delivered within the hydrogel remained viable longer and demonstrated enhanced engraftment efficiency than those delivered via injection. Engrafted MSCs were found to differentiate into fibroblasts, pericytes and endothelial cells but did not contribute to the epidermis. Wounds treated with MSC-seeded hydrogels demonstrated significantly enhanced angiogenesis, which was associated with increased levels of VEGF and other angiogenic cytokines within the wounds. Our data suggest that biomimetic hydrogels provide a functional niche capable of augmenting MSC regenerative potential and enhancing wound healing.
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Pushing back: wound mechanotransduction in repair and regeneration.
J. Invest. Dermatol.
PUBLISHED: 07-21-2011
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Human skin is a highly specialized mechanoresponsive interface separating our bodies from the external environment. It must constantly adapt to dynamic physical cues ranging from rapid expansion during embryonic and early postnatal development to ubiquitous external forces throughout life. Despite the suspected role of the physical environment in cutaneous processes, the fundamental molecular mechanisms responsible for how skin responds to force remain unclear. Intracellular pathways convert mechanical cues into biochemical responses (in a process known as mechanotransduction) via complex mechanoresponsive elements that often blur the distinction between physical and chemical signaling. For example, cellular focal adhesion components exhibit dual biochemical and scaffolding functions that are critically modulated by force. Moreover, the extracellular matrix itself is increasingly recognized to mechanically regulate the spatiotemporal distribution of soluble and matrix-bound ligands, underscoring the importance of bidirectional crosstalk between cells and their physical environment. It seems likely that a structural hierarchy exists to maintain both cells and matrix in mechanical homeostasis and that dysregulation of this architectural integrity may underlie or contribute to various skin disorders. An improved understanding of these interactions will facilitate the development of novel biophysical materials and mechanomodulatory approaches to augment wound repair and regeneration.
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Comparative healing of human cutaneous surgical incisions created by the PEAK PlasmaBlade, conventional electrosurgery, and a standard scalpel.
Plast. Reconstr. Surg.
PUBLISHED: 06-25-2011
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The authors investigated thermal injury depth, inflammation, and scarring in human abdominal skin by comparing the histology of incisions made with a standard "cold" scalpel blade, conventional electrosurgery, and the PEAK PlasmaBlade, a novel, low-thermal-injury electrosurgical instrument.
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Improving cutaneous scar formation by controlling the mechanical environment: large animal and phase I studies.
Ann. Surg.
PUBLISHED: 05-25-2011
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To test the hypothesis that the mechanical environment of cutaneous wounds can control scar formation.
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Pullulan hydrogels improve mesenchymal stem cell delivery into high-oxidative-stress wounds.
Macromol Biosci
PUBLISHED: 05-19-2011
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Cell-based therapies for wound repair are limited by inefficient delivery systems that fail to protect cells from the acute inflammatory environment. Here, a biomimetic hydrogel system is described that is based on the polymer pullulan, a carbohydrate glucan known to exhibit potent antioxidant capabilities. It is shown that pullulan hydrogels are an effective cell delivery system and improve mesenchymal stem cell survival and engraftment in high-oxidative-stress environments. The results suggest that glucan hydrogel systems may prove beneficial for progenitor-cell-based approaches to skin regeneration.
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Antimycotic ciclopirox olamine in the diabetic environment promotes angiogenesis and enhances wound healing.
PLoS ONE
PUBLISHED: 03-30-2011
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Diabetic wounds remain a major medical challenge with often disappointing outcomes despite the best available care. An impaired response to tissue hypoxia and insufficient angiogenesis are major factors responsible for poor healing in diabetic wounds. Here we show that the antimycotic drug ciclopirox olamine (CPX) can induce therapeutic angiogenesis in diabetic wounds. Treatment with CPX in vitro led to upregulation of multiple angiogenic genes and increased availability of HIF-1?. Using an excisional wound splinting model in diabetic mice, we showed that serial topical treatment with CPX enhanced wound healing compared to vehicle control treatment, with significantly accelerated wound closure, increased angiogenesis, and increased dermal cellularity. These findings offer a promising new topical pharmacologic therapy for the treatment of diabetic wounds.
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Vascular anastomosis using controlled phase transitions in poloxamer gels.
Nat. Med.
PUBLISHED: 03-01-2011
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Vascular anastomosis is the cornerstone of vascular, cardiovascular and transplant surgery. Most anastomoses are performed with sutures, which are technically challenging and can lead to failure from intimal hyperplasia and foreign body reaction. Numerous alternatives to sutures have been proposed, but none has proven superior, particularly in small or atherosclerotic vessels. We have developed a new method of sutureless and atraumatic vascular anastomosis that uses US Food and Drug Administration (FDA)-approved thermoreversible tri-block polymers to temporarily maintain an open lumen for precise approximation with commercially available glues. We performed end-to-end anastomoses five times more rapidly than we performed hand-sewn controls, and vessels that were too small (<1.0 mm) to sew were successfully reconstructed with this sutureless approach. Imaging of reconstructed rat aorta confirmed equivalent patency, flow and burst strength, and histological analysis demonstrated decreased inflammation and fibrosis at up to 2 years after the procedure. This new technology has potential for improving efficiency and outcomes in the surgical treatment of cardiovascular disease.
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An information theoretic, microfluidic-based single cell analysis permits identification of subpopulations among putatively homogeneous stem cells.
PLoS ONE
PUBLISHED: 02-23-2011
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An incomplete understanding of the nature of heterogeneity within stem cell populations remains a major impediment to the development of clinically effective cell-based therapies. Transcriptional events within a single cell are inherently stochastic and can produce tremendous variability, even among genetically identical cells. It remains unclear how mammalian cellular systems overcome this intrinsic noisiness of gene expression to produce consequential variations in function, and what impact this has on the biologic and clinical relevance of highly purified cell subgroups. To address these questions, we have developed a novel method combining microfluidic-based single cell analysis and information theory to characterize and predict transcriptional programs across hundreds of individual cells. Using this technique, we demonstrate that multiple subpopulations exist within a well-studied and putatively homogeneous stem cell population, murine long-term hematopoietic stem cells (LT-HSCs). These subgroups are defined by nonrandom patterns that are distinguishable from noise and are consistent with known functional properties of these cells. We anticipate that this analytic framework can also be applied to other cell types to elucidate the relationship between transcriptional and phenotypic variation.
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The role of stem cells in cutaneous wound healing: what do we really know?
Plast. Reconstr. Surg.
PUBLISHED: 01-05-2011
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Wound repair is a complex process involving the orchestrated interaction of multiple growth factors, cytokines, chemokines, and cell types. Dysregulation of this process leads to problems such as excessive healing in the form of keloids and hypertrophic scars and chronic, nonhealing wounds. These issues have broad global implications. Stem cells offer enormous potential for enhancing tissue repair and regeneration following injury. The rapidly developing fields of stem cell biology and skin tissue engineering create translational opportunities for the development of novel stem cell-based wound-healing therapies.
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Statistics in medicine.
Plast. Reconstr. Surg.
PUBLISHED: 01-05-2011
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The scope of biomedical research has expanded rapidly during the past several decades, and statistical analysis has become increasingly necessary to understand the meaning of large and diverse quantities of raw data. As such, a familiarity with this lexicon is essential for critical appraisal of medical literature. This article attempts to provide a practical overview of medical statistics, with an emphasis on the selection, application, and interpretation of specific tests. This includes a brief review of statistical theory and its nomenclature, particularly with regard to the classification of variables. A discussion of descriptive methods for data presentation is then provided, followed by an overview of statistical inference and significance analysis, and detailed treatment of specific statistical tests and guidelines for their interpretation.
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Akt-mediated mechanotransduction in murine fibroblasts during hypertrophic scar formation.
Wound Repair Regen
PUBLISHED: 12-06-2010
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Although numerous factors are implicated in skin fibrosis, the exact pathophysiology of hypertrophic scarring remains unknown. We recently demonstrated that mechanical force initiates hypertrophic scar formation in a murine model, potentially enhancing cellular survival through Akt. Here, we specifically examined Akt-mediated mechanotransduction in fibroblasts using both strain culture systems and our murine scar model. In vitro, static strain increased fibroblast motility, an effect blocked by wortmannin (a phosphoinositide-3-kinase/Akt inhibitor). We also demonstrated that high-frequency cyclic strain was more effective at inducing Akt phosphorylation than low frequency or static strain. In vivo, Akt phosphorylation was induced by mechanical loading of dermal fibroblasts in both unwounded and wounded murine skin. Mechanically loaded scars also exhibited strong expression of ?-smooth muscle actin, a putative marker of pathologic scar formation. In vivo inhibition of Akt increased apoptosis but did not significantly abrogate hypertrophic scar development. These data suggest that although Akt signaling is activated in fibroblasts during mechanical loading of skin, this is not the critical pathway in hypertrophic scar formation. Future studies are needed to fully elucidate the critical mechanotransduction components and pathways which activate skin fibrosis.
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Engineered pullulan-collagen composite dermal hydrogels improve early cutaneous wound healing.
Tissue Eng Part A
PUBLISHED: 11-17-2010
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New strategies for skin regeneration are needed to address the significant medical burden caused by cutaneous wounds and disease. In this study, pullulan-collagen composite hydrogel matrices were fabricated using a salt-induced phase inversion technique, resulting in a structured yet soft scaffold for skin engineering. Salt crystallization induced interconnected pore formation, and modification of collagen concentration permitted regulation of scaffold pore size. Hydrogel architecture recapitulated the reticular distribution of human dermal matrix while maintaining flexible properties essential for skin applications. In vitro, collagen hydrogel scaffolds retained their open porous architecture and viably sustained human fibroblasts and murine mesenchymal stem cells and endothelial cells. In vivo, hydrogel-treated murine excisional wounds demonstrated improved wound closure, which was associated with increased recruitment of stromal cells and formation of vascularized granulation tissue. In conclusion, salt-induced phase inversion techniques can be used to create modifiable pullulan-collagen composite dermal scaffolds that augment early wound healing. These novel biomatrices can potentially serve as a structured delivery template for cells and biomolecules in regenerative skin applications.
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The basic science of vascular biology: implications for the practicing surgeon.
Plast. Reconstr. Surg.
PUBLISHED: 11-03-2010
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A thorough understanding of vascular biology will assist the reconstructive surgeon in both operative planning and development of novel surgical approaches to treat chronic wounds and tissue loss, and to optimize regenerative strategies for tissue reconstruction. In this review, several fundamental concepts of the basic science of vascular biology are discussed, with specific emphasis on the clinical implications most relevant to the reconstructive surgeon. Topics include the vascular physiology of tissue flaps and grafts, the principles of neovascularization including angiogenesis and vasculogenesis, and the basic concepts of bioengineering of vascularized tissue constructs for use in reconstruction. As basic science research increases our collective understanding of vascular physiology--specifically, in the areas of neovascularization and tissue engineering--reconstructive surgeons will be able to improve treatment of the sequelae of ischemic injuries, tissue loss, and chronic wounds.
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Surgical approaches to create murine models of human wound healing.
J. Biomed. Biotechnol.
PUBLISHED: 09-12-2010
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Wound repair is a complex biologic process which becomes abnormal in numerous disease states. Although in vitro models have been important in identifying critical repair pathways in specific cell populations, in vivo models are necessary to obtain a more comprehensive and pertinent understanding of human wound healing. The laboratory mouse has long been the most common animal research tool and numerous transgenic strains and models have been developed to help researchers study the molecular pathways involved in wound repair and regeneration. This paper aims to highlight common surgical mouse models of cutaneous disease and to provide investigators with a better understanding of the benefits and limitations of these models for translational applications.
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Tissue engineering in plastic surgery: a review.
Plast. Reconstr. Surg.
PUBLISHED: 09-03-2010
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Novel tissue- and organ-engineering strategies are needed to address the growing need for replacement biological parts. Collective progress in stem cell technology, biomaterials, engineering, and molecular medicine has advanced the state of regenerative medicine, yet many hurdles to clinical translation remain. Plastic surgeons are in an ideal position to capitalize on emerging technologies and will be at the forefront of transitioning basic science research into the clinical reconstructive arena. This review highlights fundamental principles of bioengineering, recent progress in tissue-specific engineering, and future directions for this exciting and rapidly evolving area of medicine.
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Stem cells.
Plast. Reconstr. Surg.
PUBLISHED: 06-18-2010
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Stem cells are self-renewing cells capable of differentiating into multiple cell lines and are classified according to their origin and their ability to differentiate. Enormous potential exists in use of stem cells for regenerative medicine. To produce effective stem cell-based treatments for a range of diseases, an improved understanding of stem cell biology and better control over stem cell fate are necessary. In addition, the barriers to clinical translation, such as potential oncologic properties of stem cells, need to be addressed. With renewed government support and continued refinement of current stem cell methodologies, the future of stem cell research is exciting and promises to provide novel reconstructive options for patients and surgeons limited by traditional paradigms.
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The SNaP system: biomechanical and animal model testing of a novel ultraportable negative-pressure wound therapy system.
Plast. Reconstr. Surg.
PUBLISHED: 05-05-2010
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Negative-pressure wound therapy is traditionally achieved by attaching an electrically powered pump to a sealed wound bed and applying subatmospheric pressure by means of gauze or foam. The Smart Negative Pressure (SNaP) System (Spiracur, Inc., Sunnyvale, Calif.) is a novel ultraportable negative-pressure wound therapy system that does not require an electrically powered pump.
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Intraoperative perfusion mapping with laser-assisted indocyanine green imaging can predict and prevent complications in immediate breast reconstruction.
Plast. Reconstr. Surg.
PUBLISHED: 03-26-2010
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Immediate breast reconstruction results in a superior cosmetic outcome. However, immediate breast reconstruction using both prosthetic and autologous techniques is associated with significantly higher complication rates than delayed procedures. These early postoperative complications are usually related to unrecognized ischemia of mastectomy skin and/or inadequate perfusion of autologous tissue used for reconstruction. Aside from clinical experience, there are no reliable tools to assist the novice surgeon with intraoperative assessment of tissue viability.
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Supercharged reverse pedicle anterolateral thigh flap in reconstruction of a massive defect: A case report.
Microsurgery
PUBLISHED: 03-19-2010
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Secondary reconstruction of lower extremity defects using local tissues is demanding and fraught with potential complications. Reconstructive efforts may be challenged by pre-existing scarring, paucity of recipient vessels, and patient co-morbidities limiting tolerance for prolonged and extensive surgery. We present a case of an 81-year-old male with a recurrent malignant melanoma invading the proximal and middle third of the tibia, who previously underwent reconstruction with the medial gastrocnemius muscle and a skin graft. After wide local re-excision and tibia fixation, a 12 cm x 28 cm reverse anterolateral thigh flap was used for soft tissue coverage. Because of the relatively large size of the flap based upon retrograde flow, we elected to supercharge the flap to augment its blood supply. Supercharging of the flap pedicle was accomplished by anastamosing the lateral circumflex femoral vessels to the anterior tibial vessels. The donor site wasclosed primarily. The flap survived entirely and successfully endured subsequent radiation therapy. Supercharging enhances reliability of the reverse anterolateral thigh flap, and thus, permits harvest of large tissue bulk for coverage of up to proximal two-thirds of the tibia.This is the first report describing successful supercharging of a large reverse anterolateral thigh flap which resulted in entire flap survival.
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Strategies for organ level tissue engineering.
Organogenesis
PUBLISHED: 03-15-2010
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The field of tissue engineering has made considerable strides since it was first described in the late 1980s. The advent and subsequent boom in stem cell biology, emergence of novel technologies for biomaterial development and further understanding of developmental biology have contributed to this accelerated progress. However, continued efforts to translate tissue-engineering strategies into clinical therapies have been hampered by the problems associated with scaling up laboratory methods to produce large, complex tissues. The significant challenges faced by tissue engineers include the production of an intact vasculature within a tissue-engineered construct and recapitulation of the size and complexity of a whole organ. Here we review the basic components necessary for bioengineering organs-biomaterials, cells and bioactive molecules-and discuss various approaches for augmenting these principles to achieve organ level tissue engineering. Ultimately, the successful translation of tissue-engineered constructs into everyday clinical practice will depend upon the ability of the tissue engineer to "scale up" every aspect of the research and development process.
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Imaging the unfolded protein response in primary tumors reveals microenvironments with metabolic variations that predict tumor growth.
Cancer Res.
PUBLISHED: 12-22-2009
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Cancer cells exist in harsh microenvironments that are governed by various factors, including hypoxia and nutrient deprivation. These microenvironmental stressors activate signaling pathways that affect cancer cell survival. While others have previously measured microenvironmental stressors in tumors, it remains difficult to detect the real-time activation of these downstream signaling pathways in primary tumors. In this study, we developed transgenic mice expressing an X-box binding protein 1 (XBP1)-luciferase construct that served as a reporter for endoplasmic reticulum (ER) stress and as a downstream response for the tumor microenvironment. Primary mammary tumors arising in these mice exhibited luciferase activity in vivo. Multiple tumors arising in the same mouse had distinct XBP1-luciferase signatures, reflecting either higher or lower levels of ER stress. Furthermore, variations in ER stress reflected metabolic and hypoxic differences between tumors. Finally, XBP1-luciferase activity correlated with tumor growth rates. Visualizing distinct signaling pathways in primary tumors reveals unique tumor microenvironments with distinct metabolic signatures that can predict for tumor growth.
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Comparative healing of surgical incisions created by the PEAK PlasmaBlade, conventional electrosurgery, and a scalpel.
Plast. Reconstr. Surg.
PUBLISHED: 12-03-2009
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The PEAK PlasmaBlade is a new electrosurgical device that uses pulsed radiofrequency to generate a plasma-mediated discharge along the exposed rim of an insulated blade, creating an effective cutting edge while the blade stays near body temperature.
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Human skin wounds: a major and snowballing threat to public health and the economy.
Wound Repair Regen
PUBLISHED: 11-12-2009
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ABSTRACT In the United States, chronic wounds affect 6.5 million patients. An estimated excess of US$25 billion is spent annually on treatment of chronic wounds and the burden is rapidly growing due to increasing health care costs, an aging population and a sharp rise in the incidence of diabetes and obesity worldwide. The annual wound care products market is projected to reach $15.3 billion by 2010. Chronic wounds are rarely seen in individuals who are otherwise healthy. In fact, chronic wound patients frequently suffer from "highly branded" diseases such as diabetes and obesity. This seems to have overshadowed the significance of wounds per se as a major health problem. For example, NIHs Research Portfolio Online Reporting Tool (RePORT; http://report.nih.gov/), directed at providing access to estimates of funding for various disease conditions does list several rare diseases but does not list wounds. Forty million inpatient surgical procedures were performed in the United States in 2000, followed closely by 31.5 million outpatient surgeries. The need for post-surgical wound care is sharply on the rise. Emergency wound care in an acute setting has major significance not only in a war setting but also in homeland preparedness against natural disasters as well as against terrorism attacks. An additional burden of wound healing is the problem of skin scarring, a $12 billion annual market. The immense economic and social impact of wounds in our society calls for allocation of a higher level of attention and resources to understand biological mechanisms underlying cutaneous wound complications.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.