Biopatterned CTLA4/Fc Matrices Facilitate Local Immunomodulation, Engraftment, and Glucose Homeostasis After Pancreatic Islet Transplantation

Wensheng Zhang, Vijay S. Gorantla, Phil G. Campbell, Yang Li, Yang Yang, Chiaki Komatsu, Lee E. Weiss, Xin Xiao Zheng, Mario G. Solari

Pancreatic islet transplantation (PIT) represents a potential therapy to circumvent the need for exogenous insulin in type 1 diabetes. However, PIT remains limited by lack of donor islets and need for long-term multi-drug immunosuppression to prevent alloimmune islet rejection. Our goal was to evaluate a local immunoregulatory strategy that sustains islet allograft survival and restores glucose homeostasis in the absence of systemic immunosuppression. Nanogram quantities of murine CTLA4/Fc fusion protein were controllably delivered within human acellular dermal matrix scaffolds using an inkjet-based biopatterning technology and co-transplanted with allogeneic islets under the renal capsule to create an immunoregulatory microenvironment around the islet allograft. We achieved long-term engraftment of small loads of allogeneic islet cells with 40% of MHC-mismatched mouse recipients maintaining sustained normoglycemia following pancreatic β-cell ablation by streptozotocin. Biopatterned CTLA4/Fc local therapy was associated with expansion of Foxp3(+) regulatory T-cells and shifts in cytokine production and gene expression from pro-inflammatory to regulatory profiles, thus substantially benefiting islet allografts survival and function. This study is a new paradigm for targeted therapies in PIT that demonstrates the favorable effects of immune alterations in the transplant milieu and suggests a unique strategy for minimizing systemic immunosuppression and promoting islet allograft survival.