Isolation and expansion of thymus‐derived regulatory T cells for use in pediatric heart transplant patients

Regulatory T-cells (Tregs) are a subset of T cells generated in the thymus with intrinsic immunosuppressive properties. Phase I clinical trials have shown safety and feasibility Treg infusion to promote immune tolerance new studies ongoing evaluate their efficacy. During heart transplantation, thymic tissue is routinely discarded providing an attractive source Tregs. In this study, we developed GMP-compatible protocol for expanding sorted thymus-derived CD3+CD4+CD25+CD127– as well CD3+CD4+CD25+CD127–CD45RA+ (RA+Tregs) cells. We aimed understand whether RA+Tregs can be isolated expanded offering advantage terms stability it has been previously circulating adult CD45RA+ show that both Tregs could large numbers presence rapamycin essential inhibit growth IFN-γ producing High levels FOXP3, CTLA4, CD25 expression, demethylation FOXP3 promoter, high suppressive ability were found no differences between RA+Tregs. After freezing thawing, all preparations maintained ability, stability, expression. The number our protocol, fold expansion, functional characteristics allow application cell population pediatric transplant patients.