Stem cell–derived β cells offer a promising approach for type 1 diabetes (T1D) treatment. However, the processes of graft infiltration and rejection by immune cells remain poorly understood in humans. In this study, autologous or allogeneic stem cell–derived islets (SC-islets) were transplanted in human immune system mice and analyzed 14 to 18 weeks later. Imaging mass cytometry revealed unique characteristics of SC-islet grafts, including a high percentage of glucagon + cells and the presence of cysts and CD57 + enterochromaffin cells, features not typically observed in endogenous or transplanted allogeneic primary pancreatic islets. Allogeneic SC-islet grafts exhibited heavy immune infiltration, cell proliferation, and pro-fibrotic processes, whereas autologous grafts showed minimal infiltration and little fibrosis. In some mice, autologous T cells expressing islet antigen-reactive (IAR) T cell receptors (TCRs) were adoptively transferred. Three weeks after transfer, autologous grafts injected with IAR-TCR + T cells showed negligible immune infiltration, even though IAR-TCR + T cells were detected in the spleen. Under the conditions tested, human SC-islet grafts were not rejected by an autologous immune system, even in the presence of autoreactive T cells, pointing to several limitations that remain to be addressed for a model of spontaneous autologous SC-islet infiltration and destruction.
Genzano et al. (Mon,) studied this question.
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