In-Depth Investigation of Donor-Specific Tolerance to Vascularized Composite Allotransplants Induced by Adipose-Derived Stem Cells

Vascularized composite allotransplantation (VCA), referring to the transplantation of an allograft composed of a variety of heterogeneous antigenic tissues. It holds great clinical potential since it can be applied to treat defects that can not be mended using autologous tissues. However, the immunological barrier between donor and recipient leads to rejection and is difficult to overcome. Although immunosuppresants such as cyclosporine A has been widely used to treat rejection clinically, various potentially serious side effects do not justify their use for non-life-saving VCAs. We therefore focus on investigating methods that will induce and maintain tolerance to the VCA and ultimately reduce reliance on long term immunosuppression. In previous study, we have applied one dose of syngeneic adipose-derived stem cells (ADSC) in conjunction to antilymphocyte serum as well as short course cyclosporine and induced tolerance at 66% of the VCA recipients. However, to further study the mechanisms to induce tolerance, a protocol to induce tolerance repeatably (ie. 100%) is critical. In this proposal, we would like to fine tune the potential technical parameters to maximize VCA survival and the reliability of tolerization protocols. Furthermore, we would like to apply the optimized protocol to study the cellular mechanisms in depth, specifically, the interaction between the infused ADSC, allograft cells and the recipient cells. Three specific aims will be addressed in this proposal as follows: 1. To acquire optimized protocol that reliably induces tolerance to VCA. To acquire maximal allograft survival, factors to be evaluated include administration frequency of ADSCs, dosage of cyclosporine A, as well as rapamycin. 2. To examine ADSC-allograft interactions with optical imaging. With luciferase- and GFP-transgenic LEW rats available, information about the cell survival, distribution, differentiation and destination of ADSC and allograft derived cells in the recipients in vivo will be followed with optical imaging in real-time fashion. 3. To study the influence of ADSCs on alloantigen-stimulated recipient cells in vitro. The effects of ADSCs on the recipients’ immune cells will be delineated by an in vitro coculture system. Splenocytes isolated from GFP-transgenic Lew rats will be employed for acquiring data derived from Lew (as recipients in VCA) specifically. Combining in vivo imaging, histological and in vitro techniques, we will be able to gain comprehensive knowledge about VCA tolerance induction at organismal, organic, cellular as well as molecular levels. In the long term, we expect the knowledge gained from this research would be applicable for establishing donor-specific tolerance in clinical CTA cases.

Project ID:PC10207-0447
External Project ID:NSC102-2314-B182-015