In vitro-derived insulin-producing cells modulate Th1 immune responses and induce IL-10 in streptozotocin-induced mouse model of pancreatic insulitis.

BACKGROUND: Insulitis is defined by the presence of immune cells infiltrating in the pancreatic islets that might progress into the complete ß-cell loss. The immunomodulatory properties of bone marrow-derived mesenchymal stem cells (BM-MSCs) have attracted much attention. This study aimed to evaluate the possible immunomodulatory effects of rat BM-MSCs and MSCs-derived insulin-producing cells (IPCs) in a mouse model of pancreatic insulitis. METHODS: Insulitis was induced in BALB/c mice using five consecutive doses of streptozotocin. MSCs or IPCs were directly injected into the pancreas of mice and their effects on the expression of Th subsets-related genes were evaluated. RESULTS: Both BM-MSCs and IPCs significantly reduced the expression of pancreatic Th1-related IFN-γ (P < 0.001 and P < 0.05, respectively) and T-bet genes (both P < 0.001). Moreover, the expression of IL-10 gene was significantly increased in IPC-treated compared to BM-MSC- or PBS-treated mice (P < 0.001 both comparisons). CONCLUSIONS: BM-MSCs and IPCs could successfully suppress pathologic Th1 immune responses in the mouse model of insulitis. However, the marked increase in IL-10 gene expression by IPCs compared to BM-MSCs suggests that their simultaneous use at the initial phase of autoimmune diabetes might be a better option to reduce inflammation but these results need to be verified by further experiments.

A simple method for the generation of insulin producing cells from bone marrow mesenchymal stem cells.

To produce insulin-producing cells (IPCs) from bone marrow mesenchymal stem cells (BM-MSCs) using a simple and cost effective method. During the initial 7 days of three-dimensional (3D) culture, BM-MSCs were cultured on 1% agar or agarose to form multicellular spheroids. Spheroids and spheroid-derived single cells (SS and SSC, respectively) were cultured in the absence of any proteinaceous growth factor in a simple specific medium for a further 7 d. The insulin content of the differentiated cells was evaluated at the mRNA and protein levels. Furthermore, the expression of pancreatic beta cells-related genes other than INS as well as the in vitro responses of IPCs to different glucose concentrations were investigated. Cellular clusters generated on agar and SS conditions (agar+SS-IPCs) stained better with beta cell specific stains and were more reactive to serum-containing insulin reactive antibodies compared with agarose-SS-IPCs. Gene expression analysis revealed that in comparison to agarose + SS-IPCs, agar+SS-IPCs expressed significantly higher levels of INS-1, INS-2, PDX-1, NKX6.1, and XBP-1. Of interest, agar+SS-IPCs expressed 2215.3 ± 120.8-fold more INS-1 gene compared to BM-MSCs. The expression of ß-cell associated genes was also higher in agar+SS-IPCs compared to the agar+SSC-IPCs. Moreover, the expression of INS-1 gene was significantly higher in agar+SS-IPCs compared with agar+SSC-IPCs after culture in media with high concentration of glucose. Compared to the most expensive and time-consuming protocols, 3D culture of MSCs on agar followed by 2D culture of cellular clusters in a minimally supplemented high glucose media produced highly potent IPCs which may pay the way to the treatment of diabetic patients.