Translate text to:
In JoVE (1)
Other Publications (11)
Articles by Allison L. Speer in JoVE
Tissue Engineering of the Intestine in a Murine Model
Erik R. Barthel1, Allison L. Speer1, Daniel E. Levin1, Frédéric G. Sala1, Xiaogang Hou1, Yasuhiro Torashima1, Clarence M. Wigfall1, Tracy C. Grikscheit1
1Children's Hospital Los Angeles, Division of Pediatric Surgery, Saban Research Institute, Keck School of Medicine of the University of Southern California
Other articles by Allison L. Speer on PubMed
Journal of Pediatric Surgery. Jul, 2008 | Pubmed ID: 18639685
Lipoblastoma is a rare, benign, adipose tissue tumor. We report the largest single institution experience managing these uncommon neoplasms.
Establishing an Acute Care Surgery Service: Lessons Learned from the Epidemiology of Emergent Non-trauma Patients and Increasing Utilization of Laparoscopy
The Journal of Trauma. Oct, 2010 | Pubmed ID: 20375915
Acute care surgery is a fellowship training model created to address the growing crisis in emergency healthcare due to decreased availability of on-call surgeons and reduction in operative procedures for trauma. Our objective was to identify the demographics and spectrum of diseases in patients presenting with non-trauma surgical emergencies and the use of laparoscopy in emergent surgery in light of implementing an acute care surgery model.
Regenerative Medicine. Sep, 2011 | Pubmed ID: 21916592
To determine the effect of VEGF overexpression on tissue-engineered small intestine (TESI) formation.
The Journal of Surgical Research. Nov, 2011 | Pubmed ID: 21571313
Gastric cancer remains the second largest cause of cancer-related mortality worldwide. Postgastrectomy morbidity is considerable and quality of life is poor. Tissue-engineered stomach is a potential replacement solution to restore adequate food reservoir and gastric physiology. In this study, we performed a detailed investigation of the development of tissue-engineered stomach in a mouse model, specifically evaluating epithelial differentiation, proliferation, and the presence of putative stem cell markers.
A Multicellular Approach Forms a Significant Amount of Tissue-engineered Small Intestine in the Mouse
Tissue Engineering. Part A. Jul, 2011 | Pubmed ID: 21395443
Tissue-engineered small intestine (TESI) has successfully been used to rescue Lewis rats after massive small bowel resection. In this study, we transitioned the technique to a mouse model, allowing investigation of the processes involved during TESI formation through the transgenic tools available in this species. This is a necessary step toward applying the technique to human therapy. Multicellular organoid units were derived from small intestines of transgenic mice and transplanted within the abdomen on biodegradable polymers. Immunofluorescence staining was used to characterize the cellular processes during TESI formation. We demonstrate the preservation of Lgr5- and DcamKl1-positive cells, two putative intestinal stem cell populations, in proximity to their niche mesenchymal cells, the intestinal subepithelial myofibroblasts (ISEMFs), at the time of implantation. Maintenance of the relationship between ISEMF and crypt epithelium is observed during the growth of TESI. The engineered small intestine has an epithelium containing a differentiated epithelium next to an innervated muscularis. Lineage tracing demonstrates that all the essential components, including epithelium, muscularis, nerves, and some of the blood vessels, are of donor origin. This multicellular approach provides the necessary cell population to regenerate large amounts of intestinal tissue that could be used to treat short bowel syndrome.
Regenerative Medicine. Nov, 2012 | Pubmed ID: 23164081
Aim: Loss of colon reservoir function after colectomy can adversely affect patient outcomes. In previous work, human fetal intestinal cells developed epithelium without mesenchyme following implantation in mice. However, for humans, postnatal tissue would be the preferred donor source. We generated tissue-engineered colon (TEC) from postnatal human organoid units. Materials & methods: Organoid units were prepared from human colon waste specimens, loaded onto biodegradable scaffolds and implanted into immunocompromised mice. After 4 weeks, human TEC was harvested. Immunofluorescence staining confirmed human origin, identified differentiated epithelial cell types and verified the presence of supporting mesenchyme. Results: Human TEC demonstrated a simple columnar epithelium. Immunofluorescence staining demonstrated human origin and the three differentiated cell types of mature colon epithelium. Key mesenchymal components (smooth muscle, intestinal subepithelial myofibroblasts and ganglion cells) were seen. Conclusion: Colon can form from human progenitor cells on a scaffold in a mouse host. This proof-of-concept experiment is an important step in transitioning TEC to human therapy.
Fibroblast Growth Factor 10-fibroblast Growth Factor Receptor 2b Mediated Signaling is Not Required for Adult Glandular Stomach Homeostasis
PloS One. 2012 | Pubmed ID: 23133671
The signaling pathways that are essential for gastric organogenesis have been studied in some detail; however, those that regulate the maintenance of the gastric epithelium during adult homeostasis remain unclear. In this study, we investigated the role of Fibroblast growth factor 10 (FGF10) and its main receptor, Fibroblast growth factor receptor 2b (FGFR2b), in adult glandular stomach homeostasis. We first showed that mouse adult glandular stomach expressed Fgf10, its receptors, Fgfr1b and Fgfr2b, and most of the other FGFR2b ligands (Fgf1, Fgf7, Fgf22) except for Fgf3 and Fgf20. Fgf10 expression was mesenchymal whereas FGFR1 and FGFR2 expression were mostly epithelial. Studying double transgenic mice that allow inducible overexpression of Fgf10 in adult mice, we showed that Fgf10 overexpression in normal adult glandular stomach increased epithelial proliferation, drove mucous neck cell differentiation, and reduced parietal and chief cell differentiation. Although a similar phenotype can be associated with the development of metaplasia, we found that Fgf10 overexpression for a short duration does not cause metaplasia. Finally, investigating double transgenic mice that allow the expression of a soluble form of Fgfr2b, FGF10's main receptor, which acts as a dominant negative, we found no significant changes in gastric epithelial proliferation or differentiation in the mutants. Our work provides evidence, for the first time, that the FGF10-FGFR2b signaling pathway is not required for epithelial proliferation and differentiation during adult glandular stomach homeostasis.
Giant Cystic Meconium Peritonitis Presenting in a Neonate with Classic Radiographic Eggshell Calcifications and Treated with an Elective Surgical Approach: a Case Report
Journal of Medical Case Reports. 2012 | Pubmed ID: 22857611
Giant cystic meconium peritonitis is relatively rare. Patients often present with nonspecific physical findings such as distension and emesis. Plain abdominal films remain invaluable for identifying the characteristic calcifications seen with a meconium pseudocyst, and large eggshell calcifications are pathognomonic for the giant cystic subtype.
Solid Pseudopapillary Tumor of the Pancreas: a Single-institution 20-year Series of Pediatric Patients
Journal of Pediatric Surgery. Jun, 2012 | Pubmed ID: 22703796
Solid pseudopapillary tumor (SPT) of the pancreas is a rare neoplasm. The objective of this study was to review our institution's experience and provide an update on current management in the pediatric population.
Mesenchymal-specific Inhibition of Vascular Endothelial Growth Factor (VEGF) Attenuates Growth in Neonatal Mice
The Journal of Surgical Research. Jan, 2012 | Pubmed ID: 21696760
Vascular endothelial growth factor (VEGF) is a key mediator of angiogenesis and vasculogenesis. However, the role of VEGF in the regulation of neonatal mouse development is not completely defined. We sought to determine the effect of VEGF inhibitionÂ on the development of the neonatal mouse using a transgenic approach.