Collagen and Endothelial Cell Coculture Improves β-Cell Functionality and Rescues Pancreatic Extracellular Matrix

Abstract

The use of biomaterials and biomaterial functionalization is a promising approach to support pancreatic islet viability posttransplantation in an effort to reduce insulin dependence for patients afflicted with diabetes mellitus type 1. Extracellular matrix (ECM) proteins are known to impact numerous reparative functions in the body. Assessing how endogenously expressed pancreatic ECM proteins are affected by posttransplant-like hypoxic conditions may provide significant insights toward the development of tissue-engineered therapeutic strategies to positively influence b-cell survival, proliferation, and functionality. Here, we investigated the expression of three relevant groups of pancreatic ECM proteins in human native tissue, including basement membrane (BM) proteins (collagen type 4 [COL4], laminins [LAM]), proteoglycans (decorin [DCN], nidogen-1 [NID1]), and fibril-forming proteins (fibronectin [FN], collagen type 1 [COL1]). In an in vitro hypoxia model, we identified that ECM proteins were differently affected by hypoxic conditions, contributing to an overall loss of b-cell functionality. The use of a COL1 hydrogel as carrier material demonstrated a protective effect on bcells mitigating the effect of hypoxia on proteoglycans as well as fibril-forming protein expression, supporting b-cell functionality in hypoxia. We further showed that providing endothelial cells (ECs) into the COL1 hydrogel improves b-cell response as well as the expression of relevant BM proteins. Our data show that b-cells benefit from a microenvironment composed of structure-providing COL1 with the incorporation of ECs to withstand the harsh conditions of hypoxia. Such hydrogels support b-cell survival and can serve as an initial source of ECM proteins to allow cell engraftment while preserving cell functionality posttransplantation.

Nidogen‐1 Mitigates Ischemia and Promotes Tissue Survival and Regeneration

“…For immunofluorescence staining, the paraffin sections were stained as previously described. [ 24–53 ] Briefly, antigen retrieval was performed consecutively in Tris‐EDTA (pH = 9.0) and citrate buffer (pH = 6.0) in a steam cooker. For the intracellular antigens, the sections were treated with 1% Triton X‐100.…”

Making human pancreatic islet organoids: Progresses on the cell origins, biomaterials and three-dimensional technologies

“…During in vitro culture, lack of physical supports, oxygen and nutrients are main reasons for the instability of human islet organoids. Biomaterial is the most suitable solution for physical supports, and it can reduce cell apoptosis and functional impairment caused by hypoxia 174 . Decreasing the size of islet organoids is another effective method to solve the instability caused by hypoxia and malnutrition.…”

The Foundation for Engineering a Pancreatic Islet Niche

“…Singular or combinatory soluble ECM hydrogels is another approach for improving islet culture, as pancreatic islets are naturally embedded in a peri-islet ECM comprised of both basement and interstitial matrix proteins [ Figure 3A (iii)]. Leveraging what is known about the native peri-islet ECM, hydrogels made of soluble collagen I, III, and IV have been created that exhibited preserved function and suppression of cell death ( 164 – 166 ). A drawback of integrating distinct and soluble ECM proteins into bulk hydrogels is that their resulting conformations and interactions with the encapsulated islets are likely non-physiological.…”