This study determined the effects of chondrocyte source, cell concentration, and growth period on cartilage production when isolated porcine cells are injected subcutaneously in a nude mouse model. Chondrocytes were isolated from both ear and articular cartilage and were suspended in Ham's F-12 medium at concentrations of 10, 20, 40, and 80 million cells per cubic centimeter. Using the nude mouse model, each concentration group was injected subcutaneously in 100-microl aliquots and was allowed to incubate for 6 weeks in vivo. In addition, cells suspended at a fixed concentration of 40 million cells per cubic centimeter were injected in 100-microl aliquots and were incubated for 1, 2, 3, 4, 5, 6, 9, and 12 weeks. Each concentration or time period studied contained a total of eight mice, with four samples harvested per mouse for a final sample size of 32 constructs. All neocartilage samples were analyzed by histologic characteristics, mass, glycosaminoglycan level, and DNA content. Control groups consisted of native porcine ear and articular cartilage. Specimen mass increased with increasing concentration and incubation time. Ear neocartilage was larger than articular neocartilage at each concentration and time period. At 40 million cells per cubic centimeter, both ear and articular chondrocytes produced optimal neocartilage, without limitations in growth. Specimen mass increased with incubation time up to 6 weeks in both ear and articular samples. No significant variations in glycosaminoglycan content were found in either articular or ear neocartilage, with respect to variable chondrocyte concentration or growth period. Although articular samples demonstrated no significant trends in DNA content over time, ear specimens showed decreasing values through 6 weeks, inversely proportional to increase in specimen mass. Although both articular and ear sources of chondrocytes have been used in past tissue-engineering studies with success, this study indicates that a suspension of ear chondrocytes injected into a subcutaneous location will produce biochemical and histologic data with greater similarity to those of native cartilage. The authors believe that this phenomenon is attributable to the local environment in which isolated chondrocytes from different sources are introduced. The subcutaneous environment of native ear cartilage accommodates subcutaneously injected ear chondrocyte transplants better than articular transplants. Native structural and biochemical cues within the local environment are believed to guide the proliferation of the differentiated chondrocytes.
Background: Living donor liver transplantation is an important strategy of procuring segmental liver allografts for pediatric patients with liver failure, as suitably sized whole donor organs are scarce. The early pediatric living donor liver transplantation experience was associated with high rates of hepatic artery thrombosis, graft loss, and mortality. Collaboration with microsurgeons for hepatic artery anastomosis in pediatric living donor liver transplantation has decreased rates of arterial complications; however, reported outcomes are limited. Methods: A 14-year retrospective review was undertaken of children at the authors’ institution who underwent living donor liver transplantation with hepatic artery anastomosis performed by a single microsurgeon using an operating microscope. Data were collected on demographics, cause of liver failure, graft donor, vessel caliber, vessel anastomosis, arterial complications, and long-term follow-up. Results: Seventy-three children with end-stage liver failure underwent living donor liver transplantation with microvascular hepatic artery anastomosis. The commonest cause for liver failure was biliary atresia (63 percent). A total of 83 end-to-end hepatic artery anastomoses were completed using an operating microscope. Hepatic artery complications occurred in five patients, consisting of three cases of kinked anastomoses that were revised without complications and two cases of hepatic artery thrombosis (3 percent), of which one resulted in graft loss and patient death. Patient survival was 94 percent at 1 year and 90 percent at 5 years. Conclusions: Microvascular hepatic artery anastomosis in pediatric patients undergoing living donor liver transplantation is associated with a low hepatic artery complication rate and excellent long-term liver graft function. Collaboration between microsurgeons and transplant surgeons can significantly reduce technical complications and improve patient outcomes. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.
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