Introduction: Pancreatic islet transplantation is an effective treatment for patients with type 1 diabetes mellitus (T1DM) with unstable metabolic control. However, the quality of islets isolated from a donor is negatively affected by the inflammatory environment related to the donors brain death and by the stress related to islet isolation and culture. To overcome islet quality loss, some studies have co-cultured islets with mesenchymal stromal cells (MSCs). Considering that MSCs release growth factors, cytokines and chemokines that support cell survival and function, we therefore hypothesized that MSC-secreted molecules would induce a trophic effect in islets during culture conditions, attenuating inflammation and decreasing apoptosis of islets. To date, no study has co-cultured human islets with human adipose-derived stem cells (ASCs) in an indirect contact environment. Thus, the aims of this study were to investigate whether co-culture of human islets with human ASCs can improve islet viability and function in vitro, and to evaluate which factors are related to the protective effect of ASCs against islet dysfunction.
Methods: Human islets were isolated according to the well-stablished method described by Ricordi et al. (1989), while human ASCs were isolated from lipoaspirates using the protocol established by Zuk et al. (2001). Islets and ASCs were cultured in three experimental groups for 24, 48 and 72 h: i) indirect co-culture of islets with an ASC monolayer (Islets/ASCs); ii) islets cultured alone; and iii) ASCs cultured alone. Islet viability was evaluated using fluorescein diacetate/propidium iodide staining, and function was assessed by glucose stimulated-insulin secretion. Growth factors, cytokines and chemokines in supernatant of all conditions were quantified using an ELISA multiplex kit. Expressions of inflammation-, oxidative-stress-, apoptosis- and endoplasmic reticulum stress-related genes in islets were quantified using qPCR.
Results: The percentage of viable islets was higher in islet/ASC group compared to islet alone in all times analyzed (P<0.001). In the same way, islets from islet/ASC group showed improved beta-cell function (P=0.001). VEGF, HFG, IL-6, IL-8, IL-10, MCP-1, IL-1β and TNF levels were increased in the supernatants of islet/ASC group compared to islet alone, mainly after 24 h of culture. Moreover, VEGF, IL-6, MCP-1, HIF-1a, CHOP, and NFKBIa genes were differentially expressed in islets from the co-culture condition compared to islet alone.
Conclusion: Co-culture of islets with ASCs seems to promote an improvement in islet viability and function, probably due to protective trophic factors secreted by ASCs.
18 May 2019 - 21 May 2019