Anti-CD3 microporous annealed particle hydrogel protects stem cell derived beta cells from autoreactive T cells

Type 1 diabetes (T1D) results from autoimmune destruction of pancreatic beta cells, leaving patients dependent on exogenous insulin and at risk of severe hypoglycemic episodes. Stem cell-derived beta-like cells (sBCs) offer a promising approach for beta cell replacement therapy, but clinical translation is limited by immune-mediated rejection, recurrent autoimmunity, and inhospitable transplantation sites. Biomaterials have been investigated to provide localized immune-isolation and immunomodulation, but foreign body responses and rapid depletion of therapeutic agents remain as obstacles to clinical translation. Here, we present a microporous annealed particle (MAP) hydrogel functionalized with an anti-CD3 monoclonal antibody (αCD3) to provide a localized immunomodulatory microenvironment for beta cell replacement therapy. MAP hydrogels consisting of guest-host interlinked polyethylene glycol-maleimide (PEG-MAL) microgels supported rapid vascularization, minimal foreign body response, and engraftment of syngeneic islets in mice. αCD3 MAP hydrogel halted T cell migration in vitro and protected transplanted sBCs from immune-mediated destruction by HLA-matched diabetogenic T cells in vivo. Subcutaneous αCD3 functionalized MAP hydrogel also protected the endogenous islets in the pancreas, demonstrating potential for systemic immune modulation. These findings establish αCD3 MAP hydrogels as a promising strategy for localized immune modulation in cell replacement therapy.