MESENCHYMAL STEM CELLS AND CELLULAR TRANSPLANTATION

J. Cwykiel¹, F. Zor¹, A. Klimczak¹, M. Siemionow¹, M. Madajka^2
1Plastic And Reconstructive Surgery, Cleveland Clinic, Cleveland/OH/UNITED STATES OF AMERICA, ²Plastic Surgery, Cleveland Clinic Foundation, Cleveland/OH/UNITED STATES OF AMERICA

Body: Introduction: Face allograft transplantation model supported by donor-recipient chimeric cell therapy or bone marrow cell therapy protocol were used to determine gene expression of tolerogenic factors (Il-10, Tgfβ, FoxP3) which play a role in allograft survival and their correlation with changes in T cell population and chimerism level in the peripheral blood. Methods: Twenty one hemiface transplantations were carried out in 6 groups. Group 1, 2- isotransplants were performed between Lewis rats (RT1^l) with or without immunosupressive protocol. Hemiface allotransplantations were performed between ACI (RT1^a) donors and Lewis (RT1^l) recipients. Recipients were treated either with continuous CsA protocol (group 3) or anti- αβTCR/CsA protocol for 7 days only (group 4). Short-term immunosuppressive protocol of anti- αβTCR/CsA for 7 days only was augmented with 4x10⁶ in vivo created donor-recipient chimeric cells - DRCC (group 5) or 100 x10⁶ bone marrow cells -BMC (group 6). Blood samples and skin biopsies from donor face allograft and adjacent recipient skin were harvested at day 7, 21, 35 post-transplantation and at the rejection time. Gene expression of tolerogenic factors such as: Il-10, Tgfβ and FoxP3 were evaluated in skin biopsies using Taqman real-time PCR. Flow cytometry analysis determined changes in T regulatory cell population and chimerism level. Results: Increased Il-10 gene expression was observed up to 35 days in allografts supported by DRCC therapy (group 5) and in group 3 under continuous CsA protocol. The levels of Tgfβ were upregulated and comparable in all assessed allograft groups except of group 6 supported by BMC and isograft controls. Up-regulation of FoxP3 gene expression was observed in groups 3 and 5 from day 7 to 35 post-transplant. At day 7 post-transplant an increased number of T regulatory cells (22.84%) and total chimerism level (60.61%) in peripheral blood were detected only in the group supported by DRCC under anti- αβTCR/CsA immunosuppressive protocol. The longest allograft survival (60 days) without continuous immunosupression was observed in group 5 (supported by DRCC). Conclusion: The results of skin biopsies from face allograft in DRCC group showed up-regulation of Il-10 gene expression which correlated with gene expression of FoxP3 and with increased T regulatory cells in the peripheral blood at day 7 post-transplantation. The longest allograft survival without continuous immunosuppression was observed in group supported by DRCC. Immunosupressive protocol of 7 days anti- αβTCR/CsA therapy facilitates development of donor specific chimerism at early stages after transplantation. These results indicate that combination of DRCC therapy under short selective immunosuppressive protocol supports face transplant engraftment and long term survival.

Disclosure: All authors have declared no conflicts of interest.