Silicon Investor (SI) -- The First Internet Community

STOCKTALK

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor. We ask that you disable ad blocking while on Silicon Investor in the best interests of our community. If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.

Biotech / Medical : Biotransplant(BTRN) -- Ignore unavailable to you. Want to Upgrade?

To: paradigm7241 who wrote (494)	1/31/2000 11:32:00 PM
From: scaram(o)uche	Respond to of 1475

Here's the "thymokidney" abstract....... Transplantation 1999 Dec 15;68(11):1684-92 Thymic transplantation in miniature swine. I. Development and function of the "thymokidney". Yamada K, Shimizu A, Ierino FL, Utsugi R, Barth RN, Esnaola N, Colvin RB, Sachs DH Transplantation Biology Research Center, Department of Pathology, Massachusetts General Hospital, Boston 02129, USA. BACKGROUND: Previous studies in our laboratory have demonstrated the importance of the thymus for rapid and stable tolerance induction in an allotransplant model. The focus of the present study was to explore the feasibility of autologous thymic transplantation to produce a new transplantable organ (thymokidney) and to examine the function of subsequent vascularized thymokidney transplants in T cell development. MATERIALS AND METHODS: Eight juvenile swine received autologous thymic grafts under the renal capsule. Thymic tissue was obtained through a partial (n=6) or complete (n=2) thymectomy, and growth of the autologous thymic graft was compared between partially and completely thymectomized animals. Two of the partially thymectomized animals received irradiated (1000 cGy) as well as non-irradiated autologous thymic grafts. Graft survival, growth and evidence of thymocyte development was determined by (a) macroscopic examination of the implanted tissue, (b) histological examination, and (c) flow cytometry. Naive CD4 SP T cells were identified by CD45RA-expression. RESULTS: Growth of transplanted thymic tissue was demonstrated in all thymic graft recipients. No difference was seen between partially and completely thymectomized animals. By POD 60, the thymic grafts exhibited normal macroscopic and microscopic structure, and normal thymocyte composition. Irradiated thymic tissue displayed a similar pattern of development, but growth was markedly delayed. To evaluate thymic function of the graft, a composite thymokidney was transplanted into a recipient which had previously been thymectomized, had few circulating CD4-single positive cells and had lost MLR reactivity. The number of CD4+/CD45RA+ cells in this animal increased steadily from POD 30 to POD 150, indicating that the thymus of the composite thymokidney allograft was functional; in addition, MLR assays demonstrated that the recipient recovered immunocompetence. CONCLUSIONS: The establishment of a thymokidney by thymic autografting to the renal subcapsular space results in normal thymic growth and function, and may provide a valuable tool for studying the role of the thymus in tolerance induction. As far as we are aware, we provide the first evidence of functional vascularized thymic graft reconstituting T cells and leading to a return of a immunocompetence in a large animal model.