Recipient Adipose-Derived Stem Cells Enhance Recipient Cell Engraftment and Prolong Allotransplant Survival in a Miniature Swine Hind-Limb Model

Donor mesenchymal stem cells could prolong vascularized composite allotransplant (VCA) survival in our previous study.However, recipient adipose tissue is easier to harvest than donor tissue for pre-conditioning modulation. Hence, this study investigated the efficacy of recipient autologous adipose-derived stem cells (rASCs) for VCA survival. The heterotopic hind-limb transplantation from female donor to male recipient was performed in out-bred miniature swine. Group-I (N=6) were untreated controls. Group-II (N=4) obtained rASC infusions (given on week 0, +1, +2, and +3). Group-III (N=4) obtained Tacrolimus (FK506, week 0~+4). Group-IV (N=8) received irradiation (day -1), FK506 (week 0~+4), and rASC infusions (week 0 , +1, +2, +3). The results revealed treatment with multiple injections of rASCs along with irradiation and FK506 resulted in statistical increase in allograft survival. The percentage of CD4+/CD25+/foxp3+ regulatory T-cells revealed a significant increase in the rASCirradiation-FK506 group as compared to controls. Analysis of recipient peripheral blood revealed that TGF-βl was significantly increased in the rASC-irradiation-FK506 group. The PCR analysis and immunohistochemical staining showed recipient sex-determining region of Y-chromosome gene expression existed in donor allo-tissues in the rASC-irradiaion-FK506 group. These results indicate recipient ASCs in addition to irradiation and transient immunosuppressant could prolong allotransplant survival, modulate T-cell regulation and enhance recipient cells engraftment into the allotransplant tissues.