3D-printed polyurethane immunoisolation bags with controlled pore architecture for macroencapsulation of islet clusters encapsulated in alginate gel

Diabetes mellitus is a fast-growing chronic metabolic condition caused by insulin deficiency or resistance, leading to lifelong insulin use. It has become one of the world’s most difficult non-communicable diseases. The goal of this study was to view the effectiveness of the combined method of macro- and microencapsulation for islet transplantation. The process of 3D printing is used to make macroencapsulation bags with regulated diffusion properties thanks to the emerging small pored channels. The ink used to manufacture 3D-printed bags with controlled specifications was polyurethane solution (13% w/v). Swelling experiments revealed that there was very little swelling and that the membrane maintained its structural stability. Alginate beads (made from 5% w/v solution) were used to microencapsulate islet cell clusters. Direct contact assay was used to confirm in vitro cytocompatibility. The insulin release from the encapsulated rabbit islets was confirmed using a glucose challenge assay. When challenged with 20 mM glucose on day 7, the encapsulated islet cells released insulin at a rate of 9.72 ± 0.65 mU/L, which was identical to the RIN-5F islet cell line control, confirming the functioning of the encapsulated islets. After 21 days of culture, the islets were shown to be viable utilizing a live–dead assay. As a result, our work demonstrates that 3D printing for macroencapsulating cells, as well as microencapsulation with alginates, is a viable scale-up technology with great potential in the field of pancreatic islet transplantation.