Decellularized human pancreatic extracellular matrix-based physiomimetic microenvironment for human islet culture.

A strategy that seeks to combine the biophysical properties of inert encapsulation materials like alginate with the biochemical niche provided by pancreatic extracellular matrix (ECM)-derived biomaterials, could provide a physiomimetic pancreatic microenvironment for maintaining long-term islet viability and function in culture. Herein, we have demonstrated that incorporating human pancreatic decellularized ECM within alginate microcapsules results in a significant increase in Glucose Stimulation Index (GSI) and total insulin secreted by encapsulated human islets, compared to free islets and islets encapsulated in only alginate. ECM supplementation also resulted in long-term (58 days) maintenance of GSI levels, similar to that observed in free islets at the first time point (day 5). At early time points in culture, ECM promoted gene expression changes through ECM- and cell adhesion-mediated pathways, while it demonstrated a mitochondria-protective effect in the long-term. STATEMENT OF SIGNIFICANCE: The islet isolation process can damage the islet extracellular matrix, resulting in loss of viability and function. We have recently developed a detergent-free, DI-water based method for decellularization of human pancreas to produce a potent solubilized ECM. This ECM was added to alginate for microencapsulation of human islets, which resulted in significantly higher stimulation index and total insulin production, compared to only alginate capsules and free islets, over long-term culture. Using ECM to preserve islet health and function can improve transplantation outcomes, as well as provide novel materials and platforms for studying islet biology in microfluidic, organ-on-a-chip, bioreactor and 3D bioprinted systems.

Improved human islets' viability and functionality with mesenchymal stem cells and arg-gly-asp tripeptides supplementation of alginate micro-encapsulated islets in vitro.

INTRODUCTION: The extension of islet transplantation to a wider number of type 1 diabetes patients is compromised by severe adverse events related to the immunosuppressant therapy required for allogenic islet transplantation. In this context, microencapsulation offers the prospects of immunosuppressive-free therapy by physically isolating islets from the immune system. However, current biomaterials need to be optimized to: improve biocompatibility, guaranty the maintenance of graft viability and functionality, and prevent fibrosis overgrowth around the capsule in vivo. Accumulating evidence suggest that mesenchymal stem cells (MSCs) and anchor points consisting of tripeptides arg-gly-asp (RGD) have cytoprotective effects on pancreatic islets. Here, we investigated the effect of supplementing reference M-rich alginate microcapsules with MSCs and RGD-G rich alginate on bioprocessing as well as on human pancreatic islets viability and functionality. METHODS: We characterized the microcapsules components, and then for the new microcapsule composite product: we analyzed the empty capsules biocompatibility and then investigated the benefits of MSCs and RGD-G rich alginate on viability and functionality on the encapsulated human pancreatic islets in vitro. We performed viability tests by confocal microscopy and glucose stimulated insulin secretion (GSIS) test in vitro to assess the functionality of naked and encapsulated islets. RESULTS: Encapsulation in reference M-rich alginate capsules induced a reduction in viability and functionality compared to naked islets. This side-effect of encapsulation was in part counteracted by the presence of MSCs but the restoration was complete with the combination of both MSCs and the RGD-G rich alginate. CONCLUSIONS: The present findings show that bioprocessing a favorable composite environment inside the M-rich alginate capsule with both MSCs and RGD-G rich alginate improves human islets survival and functionality in vitro.