Translate this page to:
In JoVE (2)
- Autologous Endothelial Progenitor Cell-Seeding Technology and Biocompatibility Testing For Cardiovascular Devices in Large Animal Model
- Parallel-plate Flow Chamber and Continuous Flow Circuit to Evaluate Endothelial Progenitor Cells under Laminar Flow Shear Stress
Other Publications (10)
Articles by Hardean E. Achneck in JoVE
Autologous Endothelial Progenitor Cell-Seeding Technology and Biocompatibility Testing For Cardiovascular Devices in Large Animal Model
Alexandra E. Jantzen1, Whitney O. Lane2, Shawn M. Gage3, Justin M. Haseltine1, Lauren J. Galinat1, Ryan M. Jamiolkowski4, Fu-Hsiung Lin3, George A. Truskey1, Hardean E. Achneck3
1Department of Biomedical Engineering, Duke University, 2School of Medicine, Duke University, 3Department of Surgery, Duke University Medical Center, 4School of Medicine, University of Pennsylvania
A method for seeding titanium blood-contacting biomaterials with autologous cells and testing biocompatibility is described. This method uses endothelial progenitor cells and titanium tubes, seeded within minutes of surgical implantation into porcine venae cavae. This technique is adaptable to many other implantable biomedical devices.
Parallel-plate Flow Chamber and Continuous Flow Circuit to Evaluate Endothelial Progenitor Cells under Laminar Flow Shear Stress
Whitney O. Lane1, Alexandra E. Jantzen2, Tim A. Carlon2, Ryan M. Jamiolkowski3, Justin E. Grenet1, Melissa M. Ley1, Justin M. Haseltine2, Lauren J. Galinat2, Fu-Hsiung Lin1, Jason D. Allen4, George A. Truskey2, Hardean E. Achneck1
1Department of Surgery, Duke University Medical Center, 2Department of Biomedical Engineering, Duke University, 3School of Medicine, University of Pennsylvania, 4Department of Medicine, Division of Cardiology, Duke University Medical Center
We are describing a method to subject adherent cells to laminar flow shear stress in a sterile continuous flow circuit. The cells' adhesion, morphology can be studied through the transparent chamber, samples obtained from the circuit for metabolite analysis and cells harvested after shear exposure for future experiments or culture.
Other articles by Hardean E. Achneck on PubMed
Journal of Clinical Gastroenterology. May-Jun, 2005 | Pubmed ID: 15815208
Adenocarcinomas arising at ileostomy sites in patients after colon resection for various diseases, such as ulcerative colitis (UC), familial adenomatous polyposis coli, and Crohn's disease, are rare occurrences but have been reported increasingly in the last 20 years. We report a case of adenocarcinoma arising in an ileostomy site in an 85-year-old woman with longstanding UC. She had pancolitis and underwent total proctocolectomy. Thirty-nine years later, her ileostomy site developed a granulation tissue-type lesion, which on initial biopsy revealed cytologic atypia in the presence of marked inflammation. A subsequent biopsy revealed adenocarcinoma with signet-ring cells and abundant extracellular mucin. Resection of the ileostomy was undertaken and a new ileostomy was performed. The literature on adenocarcinoma arising in the 23 patients with ulcerative colitis who received a Brooke or Kock ileostomy and had no prior history of neoplasm is reviewed.
The Annals of Thoracic Surgery. Oct, 2007 | Pubmed ID: 17888967
Advances in graft materials, hemostasis, and surgical techniques have facilitated surgery on the thoracic aorta. We investigate the current safety level of these operations--for the purposes of enabling risk/benefit decisions for surgery and also to serve as a benchmark for comparison with emerging endovascular approaches.
Vascular. Mar-Apr, 2008 | Pubmed ID: 18544302
Intraoperative control of bleeding during any surgical procedure is vital for achieving a positive patient outcome. Hemostasis can be achieved through practical and effective systemic or topical approaches. A variety of hemostatic methods can be employed, ranging from simple manual pressure application with one finger to electrical tissue cauterization, systemic administration of blood products, and systemic administration or topical application of procoagulation agents. The key to surgical success is critically dependent on knowledgeable use of a method appropriate for the level of bleeding experienced by the patient. Topical agents can be effective as adjuncts to aid in hemostasis when bleeding is not controllable with pressure application, vessel ligation, or electrocautery. Such adjunctive hemostatic treatments include topical gelatins, collagens, oxidized celluloses, thrombin and fibrin sealants, synthetic glues, and glutaraldehyde-based glues. As with the use of systemically delivered hemostatic agents, topical treatments also carry risks with their use, and their efficacy has not been extensively studied in large randomized, placebo-controlled prospective studies. The effective use of topical agents is highly dependent on the surgeon's experience or preference and their availability in the surgical setting. In this article, we review the currently available topical hemostatic agents, compare their efficacy, and give general recommendations for their use in the operating room.
Vascular. Mar-Apr, 2008 | Pubmed ID: 18544308
To effectively balance bleeding and clotting in surgical patients, the surgeon needs a fundamental knowledge of coagulation biology. The endothelium and activated platelets play crucial roles in coagulation. Activated platelets and damaged endothelial cells provide a platform of negatively charged phospholipids that not only bind coagulation factors and their complexes but also accelerate the conversion of inactive zymogens to active serine proteases. Endothelial shear stress also plays a pivotal role in coagulation and thrombosis by stimulating release of nitric oxide (NO) at the vascular interface, upregulating endothelial nitric oxide synthase (eNOS), and further mediating eNOS activation through direct phosphorylation. The effects of low shear stress result in a prothrombotic state and have been implicated in the etiopathology of atherosclerosis. Correctly diagnosing and appropriately treating perioperative bleeding in surgical patients require a basic understanding of the most common bleeding and clotting disorders. This article provides an overview of the characteristic features of common coagulopathic conditions and their treatment options. Given the challenge of balancing bleeding and clotting in surgical patients, hemostatic management must be tailored to each patient and should take into account the patient's genetic and acquired risk factors and the acute disturbances in bleeding and clotting caused by surgical intervention.
Regenerating Titanium Ventricular Assist Device Surfaces After Gold/palladium Coating for Scanning Electron Microscopy
Microscopy Research and Technique. Jan, 2010 | Pubmed ID: 19642216
Titanium is one of the most commonly used materials for implantable devices in humans. Scanning electron microscopy (SEM) serves as an important tool for imaging titanium surfaces and analyzing cells and other organic matter adhering to titanium implants. However, high-vacuum SEM imaging of a nonconductive sample requires a conductive coating on the surface. A gold/palladium coating is commonly used and to date no method has been described to "clean" such gold/palladium covered surfaces for repeated experiments without etching the titanium itself. This constitutes a major problem with titanium-based implantable devices which are very expensive and thus in short supply. Our objective was to devise a protocol to regenerate titaniumsurfaces after SEM analysis. In a series of experiments, titanium samples from implantable cardiac assist devices were coated with fibronectin, seeded with cells and then coated with gold/palladium for SEM analysis. X-ray photoelectron spectroscopy spectra were obtained before and after five different cleaning protocols. Treatment with aqua regia (a 1:3 solution of concentrated nitric and hydrochloric acid), with or without ozonolysis, followed by sonication in soap solution and sonication in deionized water, allowed regenerating titanium surfaces to their original state. Atomic force microscopy confirmed that the established protocol did not alter the titanium microstructure. The protocol described herein is applicable to almost all titanium surfaces used in biomedical sciences and because of its short exposure time to aqua regia, will likely work for many titanium alloys as well.
Annals of Surgery. Feb, 2010 | Pubmed ID: 20010084
Since ancient times we have attempted to facilitate hemostasis by application of topical agents. In the last decade, the number of different effective hemostatic agents has increased drastically. In order for the modern surgeon to successfully choose the right agent at the right time, it is essential to understand the mechanism of action, efficacy and possible adverse events as they relate to each agent. In this article we provide a comprehensive review of the most commonly used hemostatic agents, subcategorized as physical agents, absorbable agents, biologic agents, and synthetic agents. We also evaluate novel hemostatic dressings and their application in the current era. Furthermore, wholesale acquisition prices for hospitals in the United States are provided to aid in cost analysis. We conclude with an expert opinion on which agent to use under different scenarios.
Seminars in Dialysis. Jan-Feb, 2010 | Pubmed ID: 20331815
Since the Fistula First Initiative was formulated in 2003, providers and payers have increasingly emphasized the need to create more arteriovenous fistulae. To maximize the chances of successful fistula maturation, a thorough understanding of the biology and surgical aspects of fistula placement are essential. A functional endothelium in the target vessels is the prerequisite for the adaptive remodeling of the vessel wall, which has to take place after fistula formation. Mechanoreceptors of the endothelium sense the increase in shear stress and, through a variety of activated signaling cascades, induce the necessary changes and vasodilation of the respective vessels. The successful fistula placement starts with a thorough preoperative evaluation, which focuses on protecting the target vessels and avoiding intravenous catheters and devices. Intraoperatively, the risk of endothelial dysfunction and hyperplasia is further minimized through an atraumatic dissection with minimal manipulation of the vein and artery. The surgical technique should also focus on decreasing the vessel compliance mismatch and avoiding an inflammatory response secondary to hematoma formation. Postoperatively, the fistula must be diligently monitored for the complications of thrombosis, postoperative steal syndrome, neuropathy, aneurysm formation, infection, and high-output cardiac failure. Early recognition of a problem is the key to saving an otherwise doomed fistula. An armamentarium of percutaneous techniques is available to the access surgeon to treat the most common causes of failed access formation. However, in some cases a surgical revision of the access site through patch angioplasty, a jump graft, and graft interposition is necessary to create a fistula which can be successfully used for hemodialysis.
Pathophysiology of Bleeding and Clotting in the Cardiac Surgery Patient: from Vascular Endothelium to Circulatory Assist Device Surface
Circulation. Nov, 2010 | Pubmed ID: 21098468
Use of Autologous Blood-derived Endothelial Progenitor Cells at Point-of-care to Protect Against Implant Thrombosis in a Large Animal Model
Biomaterials. Nov, 2011 | Pubmed ID: 21840592
Titanium (Ti) is commonly utilized in many cardiovascular devices, e.g. as a component of Nitinol stents, intra- and extracorporeal mechanical circulatory assist devices, but is associated with the risk of thromboemboli formation. We propose to solve this problem by lining the Ti blood-contacting surfaces with autologous peripheral blood-derived late outgrowth endothelial progenitor cells (EPCs) after having previously demonstrated that these EPCs adhere to and grow on Ti under physiological shear stresses and functionally adapt to their environment under flow conditions ex vivo. Autologous fluorescently-labeled porcine EPCs were seeded at the point-of-care in the operating room onto Ti tubes for 30 min and implanted into the pro-thrombotic environment of the inferior vena cava of swine (n = 8). After 3 days, Ti tubes were explanted, disassembled, and the blood-contacting surface was imaged. A blinded analysis found all 4 cell-seeded implants to be free of clot, whereas 4 controls without EPCs were either entirely occluded or partially thrombosed. Pre-labeled EPCs had spread and were present on all 4 cell-seeded implants while no endothelial cells were observed on control implants. These results suggest that late outgrowth autologous EPCs represent a promising source of lining Ti implants to reduce thrombosis in vivo.
The Biocompatibility of Titanium Cardiovascular Devices Seeded with Autologous Blood-derived Endothelial Progenitor Cells: EPC-seeded Antithrombotic Ti Implants
Biomaterials. Jan, 2011 | Pubmed ID: 20926131
Implantable and extracorporeal cardiovascular devices are commonly made from titanium (Ti) (e.g. Ti-coated Nitinol stents and mechanical circulatory assist devices). Endothelializing the blood-contacting Ti surfaces of these devices would provide them with an antithrombogenic coating that mimics the native lining of blood vessels and the heart. We evaluated the viability and adherence of peripheral blood-derived porcine endothelial progenitor cells (EPCs), seeded onto thin Ti layers on glass slides under static conditions and after exposure to fluid shear stresses. EPCs attached and grew to confluence on Ti in serum-free medium, without preadsorption of proteins. After attachment to Ti for 15 min, less than 5% of the cells detached at a shear stress of 100 dyne / cm(2). Confluent monolayers of EPCs on smooth Ti surfaces (Rq of 10 nm), exposed to 15 or 100 dyne/cm(2) for 48 h, aligned and elongated in the direction of flow and produced nitric oxide dependent on the level of shear stress. EPC-coated Ti surfaces had dramatically reduced platelet adhesion when compared to uncoated Ti surfaces. These results indicate that peripheral blood-derived EPCs adhere and function normally on Ti surfaces. Therefore EPCs may be used to seed cardiovascular devices prior to implantation to ameliorate platelet activation and thrombus formation.