Tumor formation following murine neural precursor cell transplantation in a rat peripheral nerve injury model

Neural stem cells show a remarkable aptitude for integration and appropriate differentiation at sites of cellular injury in central nervous system (CNS) disease models. In contrast, reports of neural stem cell applications in peripheral nerve injury models are sparse. In this study we sought to determine if the C17.2 cell line would respond to cues in the microenvironment of the injured peripheral nerve and enhance neuronal regeneration in rodent sciatic nerve injury models. We transplanted C17.2 into several sciatic nerve injury models in 45 nude rats, including nerve transection, nerve crush, and nerve gap models. Twelve of the animals in this study developed large tumors at the site of neural stem cell transplants. Histologically, the tumors resembled neuroblastomas. The tumors were confirmed to be of transplanted cell origin by positive beta-galactosidase staining. Tumors occurred only in models where the nerve remained intact or where continuity of the nerve was restored. We concluded that C17.2 transplantation into peripheral nerve injury models resulted in a high rate of tumor formation. This study demonstrates that the success of neural precursor transplants in the CNS cannot necessarily be extrapolated to the peripheral nervous system.

From experimental rat hindlimb to clinical face composite tissue allotransplantation: Historical background and current status

The purpose of this article is to review the historical background and clinical status of composite tissue allotransplantation and to discuss the scientific evolution of clinical face transplantation. Composite tissue allotransplantation (CTA) rapidly progressed in the 1980s with the discovery of cyclosporine. Although the most success has been achieved with hand transplantation, others have made progress with allografts of trachea, peripheral nerve, flexor tendon apparatus, vascularized knee, larynx, abdominal wall, and most recently, partial face. The world's first partial face allotransplantation occurred in November 2005 in France. In April of 2006, there was a second performed in China. As of today, there are now multiple institutions with plans to attempt the world's first full facial/scalp transplant. Complete facial/scalp allotransplantation offers a viable alternative for unfortunate individuals suffering severe facial disfigurement and is a product of many decades of experimental research, beginning with rat hindlimb allografts.

Tissue-Engineered Cartilage Composite With Expanded Polytetrafluoroethylene Membrane

The authors report a new approach using expanded polytetrafluoroethylene (ePTFE) membrane as pseudoperichondrium to support engineered cartilage. Swine auricular chondrocytes were isolated and mixed with fibrin glue to achieve a final concentration of 40 x 10(6) cells per milliliter. The fibrin glue-cell suspension was assembled with ePTFE and the constructs were implanted into the dorsal subcutaneous pockets of nude mice for 12 weeks. Two experimental groups were prepared in this study: (1) ePTFE placed in the central part of the specimen in group 1 and (2) ePTFE placed on the outside surfaces in group 2. All specimens were subjected to histological and gross mechanical evaluation. Histological results showed neocartilage formation in both groups. The integration between neocartilage and ePTFE forms a tight bond. Gross mechanical testing revealed that the flexibility of specimens in group 2 were similar to that of native cartilage with intact perichondrium, whereas the flexibility of specimens in group 1 were poor. From these results the authors conclude that it is possible to produce a tissue-engineered cartilage framework using ePTFE as a support material to simulate the perichondrium.