Post-Transplant Characterization of Long-Term Functional hESC-Derived Pancreatic Endoderm Grafts.

The paucity of human donors confines the broadened application of β-cell replacement therapy. Insulin-producing cells derived from human embryonic stem cells (hESC), have been recently investigated clinically as a feasible surrogate to primary tissue. Herein, we examine the long-term efficacy of hESC derived pancreatic endoderm cells (PEC) to maintain normoglycemia post-transplant and characterize graft's phenotype.Chemically induced diabetic mice were transplanted with PEC into the subcutaneous device-less site. Transplant function was assessed through non-fasting blood glucose measurements, intraperitoneal glucose tolerance testing (IPGTT) and human C-peptide secretion for 517 days. Explanted grafts were assessed for ex vivo function and immunohistochemically. All PEC recipients (n=8) maintained normoglycemia until graft retrieval. IPGTTs at 365 and 517 days post-transplant did not differ (P>0.05), however, both demonstrated superior glucose clearance compared to non-diabetic and transplant controls (P<0.001). Serum C-peptide levels demonstrated significant glucose-responsiveness (fasted vs. stimulated) (P<0.01). Small intra-graft cysts were palpable in all mice, which resolved but recurred after aspiration, showed monomorphic neuroendocrine proliferation and lined by ductal epithelium. Explanted grafts demonstrated similar insulin secretory capacity as human islets and stained positively for endocrine cells. Our results demonstrate the ability of PEC to differentiate in vivo and restore glycemic control while confirming minimal proliferative and absence of neoplastic change during the time evaluated.