In vitro generation of peri-islet basement membrane-like structures.

The peri-islet extracellular matrix (ECM) is a key component of the microenvironmental niche surrounding pancreatic islets of Langerhans. The cell anchorage and signaling provided by the peri-islet ECM is critical for optimum beta cell glucose responsiveness, but islets lose this important native ECM when isolated for transplantation or in vitro studies. Here, we established a method to construct a peri-islet ECM on the surfaces of isolated rat and human islets by the co-assembly from solution of laminin, nidogen and collagen IV proteins. Successful deposition of contiguous peri-islet ECM networks was confirmed by immunofluorescence, western blot, and transmission electron microscopy. The ECM coatings were disrupted when assembly occurred in Ca2+/Mg2+-free conditions. As laminin network polymerization is divalent cation dependent, our data are consistent with receptor-driven ordered ECM network formation rather than passive protein adsorption. To further illustrate the utility of ECM coatings, we employed stem cell derived beta-like cell clusters (sBCs) as a renewable source of functional beta cells for cell replacement therapy. We observe that sBC pseudo-islets lack an endogenous peri-islet ECM, but successfully applied our approach to construct a de novo ECM coating on the surfaces of sBCs.

Engineered microenvironments and microdevices for modeling the pathophysiology of type 1 diabetes.

The pathophysiology of type 1 diabetes is a complex process involving tightly controlled microenvironments, a number of highly specific immune cell - islet cell interactions, and the eventual breaking of immune tolerance leading to beta cell death. Modeling this process can provide researchers with powerful insights into how and when to best provide treatment, but has proven difficult to accurately model due to its complex nature and differences between animal models and humans. Much progress has been made in determining the genetic, molecular, and cellular mechanisms of type 1 diabetes, yet translating that knowledge to clinical treatments remains challenging. Thus, there exists a capabilities gap between understanding the disease pathophysiology and engineering effective clinical treatment strategies. Biomimetic modeling of human type 1 diabetes is a valuable tool to study and manipulate islet function and can be employed to address immunological aspects of type 1 diabetes. This article will review recent advances in this field, and will suggest ways to synergize systems to model and observe the pathophysiology of autoimmune diabetes with bioengineered therapeutic strategies.