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Purpose: Phosphatidylserine (PS)-deficient small extracellular vesicle (sEV) subpopulations (PS(−) sEVs) circulate in blood for long periods; hence, they are expected to have therapeutic applications. However, limited production of PS(−) sEVs makes their application difficult. In this study, a method for the preparation of such populations using an enzymatic reaction was developed. Methods: Bulk sEVs collected from a cell culture supernatant via ultracentrifugation were subjected to an enzymatic reaction using phosphatidylserine decarboxylase (PSD). The yield of PS(−) sEVs was estimated using magnetic beads that bind to PS(+) sEVs. Then, the physical properties and pharmacokinetics (PK) of the sEVs were evaluated. Results: Enzymatic depletion of PS exposed on sEV surfaces using PSD increased the yield of PS(−) sEVs. PSD treatment hardly changed the physicochemical properties of PS(−) sEVs. Moreover, the serum concentration profile and PK parameters of the PS(−) sEVs derived from PSD-treated bulk sEVs indicated a long blood-circulation half-life. Conclusions: Treatment of sEVs with PSD successfully reduced surface PS levels and increased the amount of the PS(−) sEV subpopulation among bulk sEVs. This protocol of efficient preparation of PS(−) sEVs based on PSD treatment, as well as information on the basic PK, can be foundational for the therapeutic application of sEVs. [ABSTRACT FROM AUTHOR]

Purpose: We previously have shown that multicellular spheroids containing insulin-secreting cells are an effective therapy for diabetic mice. Here we attempted to increase insulin secretion by incorporating other cell types into spheroids. Materials and Methods: Multicellular spheroids of mouse MIN6 pancreatic β cells were formed in microwells alone and with aortic vascular endothelial MAEC cells or embryo fibroblast NIH3T3 cells. mRNA expression of insulin genes and insulin secretion of MIN6 cells in each spheroid were measured by real-time PCR and an insulin ELIZA kit. Moreover, collagen IV expression in each spheroid was analyzed by western blot. Results: In all cases, uniformly sized (about 300 μm) multicellular spheroids were obtained. MAEC or NIH3T3 cell incorporation into MIN6 spheroids significantly increased mRNA expression of insulin genes and insulin secretion. In addition, collagen IV expression, which was reported to enhance insulin secretion from pancreatic β cells, also increased in their spheroids. Conclusions: The formation of mixed multicellular spheroids containing collagen IV-expressing cells can improve the insulin secretion from insulin-secreting MIN6 cells, and mixed multicellular spheroids can be a potent therapeutic option for patients with type I diabetes mellitus. [ABSTRACT FROM AUTHOR]