Summary: | The induction of donor-specific transplant tolerance has always been a central problem for small bowel transplantation, which is thought to be the best therapy for end-stage bowel failure. With the development of new tolerance-inducing strategies, mixed chimerism induced by co-stimulation blockade has become most potent for tolerance of allografts such as skin, kidney and heart. However, a lack of clinically available co-stimulation blockers has hindered efficient application in humans. Furthermore, unlike those for other types of solid organ transplantation, strategies to induce robust mixed chimerism for intestinal allografts have not been fully developed. To improve current mixed chimerism induction protocols for future clinical application, we developed a new protocol using donor-specific regulatory T (Treg) cells from mice with heart allograft tolerance, clinically available immunosuppressive drugs, and low doses of irradiation. Our results demonstrated that donor-specific Treg cells acquired from tolerant mice after in vitro expansion generate stable chimerism and lead to acceptance of intestinal allograft. Increased intragraft Treg cells and clonal deletion both contribute to the development of small bowel transplantation tolerance.
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