Microfluidically fabricated fibers containing pancreatic islets and mesenchymal stromal cells improve longevity and sustained normoglycemia in diabetic rats.

Type 1 diabetes mellitus is an autoimmune disease characterized by the loss of pancreatic islet β cells. Insulin injections and pancreas transplants are currently available therapies. The former requires daily insulin injections, while the latter is constrained by donor organ availability. Islet transplantation is a promising alternative treatment for type 1 diabetes mellitus that may overcome the limitations of previous techniques. Two challenges, however, must be addressed: limited cell retention as a result of the immune response and limited function of the transplanted cells that survive. To address these problems, we developed a microfluidic technology for a one-step generation of islet-laden fibers to protect them from immune response. This approach enables continuous generation of microfibers with a diameter suitable for islet encapsulation (275 µm). We, then, transplanted islet-laden fibers into diabetic Wistar rats. While islet-laden fibers alone were unable to restore normoglycemia in diabetic rats, adding mesenchymal stromal cells restored normoglycemia for an extended period of time. It increased the animals' lifespan by up to 75 days. Additionally, it improved the glucose-stimulated response of islets to the point where there was no significant difference between the treatment group and the healthy animals. Additionally, the presence of mesenchymal stromal cells suppressed the immune response, as seen by decreased levels of pro-inflammatory cytokines such as TNF-α. Taken together, these fibers including islet and mesenchymal stromal cells provide a versatile platform for concurrently improving cell preservation and functioning following in vivo transplantation.