Engineering functional islets from cultured cells

Although pancreatic islet transplantation can now be performed minimally invasively in patients with type 1 diabetes, the availability of functional islet donors remains the chief obstacle to widespread clinical application. Tissue engineering islet cells in vitro that function when implanted in vivo provides a solution to this problem.

Rat pancreatic islets were enzymatically dissociated into a single-cell suspension and seeded onto a polyglycolic acid (PGA) scaffold. The cells were cultured in CMRL 1099 medium containing epidermal growth factor, nerve growth factor, and insulin-like growth factor for 5 days. The PGA and isolated cells were then suspended in a thermoreversible gelatin polymer (TGP) with insulin, transferring and selenous acid, in F-12 and Dulbecco's modified Eagle's medium, to proliferate over a 40-day period. After the degradation of the PGA fibers, the TGP was removed using cold temperature extraction. The tissue-engineered (TE) islets were then collected manually and transplanted beneath the kidney capsule of Streptozotocin (STZ)-induced diabetic nude mice.

All mice that received the TE islets reverted from the induced hyperglycemic state to a state of normoglycemia (n = 6). The treated mice demonstrated normal oral glucose tolerance tests. Testing for the species-specific C-peptide allowed discrimination between the exogenous insulin secretions of the TE rat islets and the endogenous secretions of the nude mice. Immunohistochemistry confirmed the multilineage potential of these TE endocrine cells, showing them capable of secreting insulin, glucagon, and somatostatin.

The ability to tissue engineer pancreatic islets in vitro, through use of PGA and TGP, that fully function in vivo to return diabetic-induced mice to state of normoglycemia has potential implications for the treatment type 1 diabetes.