Neovascularization and functional assessment of human pancreatic islets encapsulated with immuno‐modulatory stem cells

Abstract

Background & ObjectiveDeveloping successful therapies based on re‐introduction of healthy pancreatic islets in diabetic patients requires new strategies to combat the immune response caused by implantation, as well as improving neovascularization and engraftment of the implant. Human amniotic epithelial cells (AECs) are immuno‐modulatory stem cells that can confer a local immune‐privileged environment in vivo, and block grafted tissue rejection [1]. The objective of this study was to develop a protocol for encapsulating islets with AECs, and examine the effects of encapsulation on islet function, and neovascularization.MethodsHuman pancreatic islets were individually placed in ultra‐low attachment round bottom wells with human islet medium, and were divided into three experimental groups: 1) islet‐only, 2) adipose‐derived stem cells (ASCs)+islet, and 3) AECs+islet. For groups 2 and 3, each islet was assumed to have ~2000 beta cells, and the stem cells were added to each well to encapsulate individual islets at 2:1 cell ratio. The temporal c‐peptide secretion level was measured after 3 and 6 days by perfusing the islets with basal and high glucose solutions using dynamic readout assay, and confirmed the functionality of the encapsulated islets. To assess the angiogenic properties of encapsulation, cell culture supernates were collected after 6 days of culture, and used for an angiogenesis array kit, to identify and compare the level of 52 angiogenic factors present in each group. The same test was repeated for ASC‐ and AEC‐only cultures to identify any effects caused by the cell encapsulation.Results & ConclusionsThe level of pro‐angiogenic factors increased in encapsulated groups compared to the islet‐only group (Fig. 1). A larger increase in angiogenic factors in encapsulated islets compared to stem cell‐only groups demonstrated a synergetic angiogenic effect caused by encapsulation of islets with ASCs and AECs. To test the angiogenic response in a physiological scenario, the islets were seeded on rat mesentery tissues, and cultured for 6 days, and the level of angiogenic response was compared between different groups. Our results highlight the effect of encapsulating human islets with ASCs and AECs on engraftment and neovascularization, and showcase the potential of the islet cell encapsulation method for a successful long‐term implantation in patients with diabetes.Support or Funding InformationThe Virginia Catalyst and UVA Center for Advanced BiomanufacturingThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.