The Potential Oligodendroglial Fate Specification Capacity of Exosomes Derived from Stem Cells of the Umbilical Cord Tissue

INTRODUCTION: The neuroregenerative effects of transplanted mesenchymal stem cells (MSC) in animal models of perinatal brain damage are presumed to rely on secreted factors including MSC-derived exosomes. Thus, the aim of this study is the evaluation of the oligodendroglial fate specification capacity of human Wharton’s jelly-derived MSC (WJ-MSC) on neural progenitor cells (NPC). METHODS: WJ-MSC-derived exosomes were isolated from culture supernatants by serial centrifugation, characterized by the expression of endosomal markers (membrane-based antibody array) and their size (electron microscopy). The exosomal microRNA (miRNA) content was assessed by real-time PCR. The exosomes were stained with the red fluorescent celltracker dye CM-DIL to analyze the potential interaction with NPC. Exosomal RNA was further fluorescently labeled to investigate its potential release into NPC. After the culture with exosomes, NPC were evaluated for the expression of proliferation and oligodendroglial differentiation markers by real-time PCR. RESULTS: WJ-MSC-derived exosomes were positive for endosomal markers, including TSG101 and ALIX, and had a mean diameter of 19 nm. The exosomes contained miRNAs that are involved in the differentiation of oligodendrocyte progenitor cells and in oligodendroglial fate determination (miR-338, miR-9, miR-19b, miR-138). Fluorescently labeled exosomal RNA was detected in NPC after co-culture. The gene expression of the transcription factor inhibitor of DNA binding protein (ID)2, which blocks oligodendrogenesis, was reduced in NPC post co-culture with exosomes. The transcription of ID4, which counteracts the function of ID2 was enhanced in NPC following incubation with exosomes. CONCLUSIONS: We successfully isolated WJ-MSC-derived exosomes. The exosomes contain miRNAs having decisive roles in oligodendroglial fate specification and differentiation, ascribing a potential neuroregenerative role to WJ-MSC-derived exosomes. Financial support by CryoSave Switzerland.