Neurobiology of human neurons (NT2N) grafted into mouse spinal cord: implications for improving therapy of spinal cord injury.

Emerging data suggest that current strategies for the treatment of spinal cord injury might be improved or augmented by spinal cord grafts of neural cells, and it is possible that grafted neurons might have therapeutic potential. Thus, here we have summarized recent studies of the neurobiology of clonal human (NT2N) neurons grafted into spinal cord of immunodeficient athymic nude mice. Postmitotic human NT2N neurons derived in vitro from an embryonal carcinoma cell line (NT2) were transplanted into spinal cord of neonatal, adolescent and adult nude mice where they became integrated into the host gray and white matter, did not migrate from the graft site, and survived for > 15 months after implantation. The neuronal phenotype of the grafted NT2N cells was similar in gray and white matter regardless of host age at implantation, and some of the processes extended by the transplanted NT2N neurons became ensheathed by oligodendrocytes. However, there were consistent differences between NT2N processes traversing white versus gray matter. Most notably, NT2N processes with a trajectory in white matter extended over much longer distances (some for > 2 cm) than those confined to gray matter. Thus, NT2N neurons grafted into spinal cord of nude mice integrated into gray as well as white matter, where they exhibited and maintained the morphological and molecular phenotype of mature neurons for > 15 months after implantation. Also, the processes extended by grafted NT2N neurons differentially responded to cues restricted to gray versus white matter. Further insight into the neurobiology of grafted human NT2N neurons in the normal and injured spinal cord of experimental animals may lead to novel and more effective strategies for the treatment of spinal cord injury.

Transplantation of highly differentiated immortalized human hepatocytes to treat acute liver failure.

BACKGROUND: Temporary support of a damaged liver by a bioartificial liver (BAL) devise is a promising approach for the treatment of acute liver failure. Although human primary hepatocytes are an ideal source of hepatic function in BAL, shortage of human livers available for hepatocyte isolation is the limiting factor for the use of this modality. A clonal human hepatocyte cell line that can grow economically in culture and exhibit liver-specific functions should be an attractive solution to this problem. METHODS: To test this alternative, primary human fetal hepatocytes were immortalized using Simian virus 40 large T antigen. To investigate the potential of the immortalized cells for BAL, we transplanted the cells into the spleen of adult rats and performed a 90% hepatectomy 12 hr later. RESULTS: One of the cloned human liver cell lines, OUMS-29, showed highly differentiated liver functions. Intrasplenic transplanting of 20x10(6) OUMS-29 cells protected the animals from hyperammonemia and the associated hepatic encephalopathy. Survival was significantly prolonged in 90% of hepatectomized rats receiving OUMS-29 cells. CONCLUSIONS: A highly differentiated immortalized human hepatocyte cell line, OUMS-29, was able to provide metabolic support during acute liver failure induced by 90% hepatectomy in rats. Essentially unlimited availability of OUMS-29 cells may be clinically useful for BAL treatment.

Growth of human paragangliomas in the subrenal capsule of the nude mouse.

Paragangliomas are generally benign, highly vascular, and slowly growing tumors of neural crest lineage that occur disproportionately in women. Surgery can manage small tumors expeditiously, but extirpation of large tumors is associated with morbidity and even mortality. Radiation therapy offers relatively good tumor control but also presents development of a secondary malignant neoplasm as a possible consequence. Cancer chemotherapeutic agents have been used only in rare metastasizing paragangliomas because they also are associated with considerable morbidity. A better understanding of the biology of human paragangliomas, to encompass the molecular biology of these tumors, is essential for the development of a less morbid, tumor-targeted therapy. This preliminary investigation is aimed at testing the hypothesis that the subrenal capsule of the nude mouse is a viable model for in vivo study of the molecular biology of human paragangliomas. None of the five tumors implanted survived for the duration of the study period. Accordingly, the nude mouse subrenal capsule does not appear to be useful in the study of human paragangliomas.