Extracellular Matrix—Key to Maintaining Function of Encapsulated Human Stem Cell Differentiated Islet Clusters Seeded into Scaffolds as a Diabetes Therapy

Background/Objectives: A stem cell therapy for type 1 diabetes (T1D) is experimentally available but only to those few humans in whom the use of systemic immunosuppression can be justified. For others with T1D, a means to deliver the islets needs to be perfected. We have previously bioengineered a removable device for this purpose and now wish to test the effect of adding extracellular matrix (ECM) derived from decellularised human pancreas to it. Methods: The complete device consists of encapsulated pluripotent stem cell differentiated islets seeded into tubular scaffolds of polycaprolactone made by melt electrospin writing and to which ECM was added. The seeded device was implanted either subcutaneously (SC) or intraperitoneally (IP) into streptozotocin diabetic immunodeficient mice. The outcome over the next few months was compared with that achieved in diabetic mice implanted IP with encapsulated islets alone. Results: The device seeded with encapsulated islets but not containing ECM functioned less well than encapsulated islets implanted alone, with lower human C-peptide production. However, when ECM was added to the seeded device and whether implanted SC or IP, islets functioned as efficiently as those implanted without use of a scaffold. Conclusions: These data provide optimism for the use of seeded scaffolds in diabetic humans in whom a single scaffold seeded with multiple encapsulated islets can more readily be removed if needed for safety reasons than can multiple encapsulated islets not seeded into a scaffold.