Human mesenchymal stem cells were exposed to diabetic sera for 7 days. Cell viability and apoptosis rate were detected by MTT and flow cytometry assays. The expression of key genes such as CD63, Alix, Rab27a, Rab27b, and Rab8b was monitored by real-time PCR. We also measured acetylcholinesterase activity and size and zeta potential of exosomes in the supernatant form diabetic cells and control. The cellular distribution of CD63 was shown by immunofluorescence imaging and western blotting. Any changes in the ultrastructure of cells were visualized by electron microscopy. Data showed a slight decrease in survival rate and an increased apoptosis in diabetic cells as compared to control (p < 0.05). By exposing cells to diabetic sera, a significant increase in the level of all genes CD63, Alix, Rab27a, Rab27b, and Rab8b was observed (p < 0.05). Flow cytometry analysis and immunofluorescence imaging confirmed increasing CD63 protein content upon treatment with diabetic sera (p < 0.05). We found an enhanced acetylcholinesterase activity in a diabetic condition which coincided with the increasing size of exosomes and decrease in zeta potential (p < 0.05). The fatty acid profile was not significantly affected by diabetic sera. Ultrastructural examination detected more accumulated cytoplasmic lipid vacuoles in diabetic cells.
Keywords: CD63-Alix-Rab axis; Diabetes mellitus type 2; Exosome biogenesis and release; Human mesenchymal stem cells.