Parallel evaluation of two promising immunoisolation strategies for beta cell replacement: Conformal coating versus double alginate encapsulation

Pancreatic islet transplantation represents a therapeutic option for type 1 diabetes patients to restore insulin secretion and glucose homeostasis. However, chronic immunosuppression is necessary to prevent graft rejection and graft function is difficult to maintain over prolonged times. Encapsulating pancreatic islets with hydrogel biomaterials represents a strategy for immunoisolation, preventing the direct contact between donor islets and recipient immune system. At the same time, hydrogels allow efficient inward diffusion of nutrients, oxygen, and glucose as well as glucose-stimulated release of insulin. Here, we compared two encapsulation technologies that have proven to be effective in preclinical models – Conformal Coating (CC) ¹ and Double Capsules (DC) ² , which are fabricated with different materials: polyethylene glycol (PEG) and alginate, respectively. We evaluated the hydrogel diffusivity properties and the functionality of human islets (HI) in CC and DC through static (GSIR) and dynamic (perifusion) glucose stimulated insulin release assays.