Exosomes released from Wharton’s jelly stem cells as potential remyelination therapy in perinatal brain injury

Abstract

Introduction: Preterm birth may lead to a maturation stop or even death of oligodendrocyte progenitor cells (OPC), resulting in overall hypomyelination, a major hallmark of perinatal brain injury. As preclinical transplantation of Wharton’s Jelly-derived mesenchymal stem cells (WJ-MSC) preserves hypomyelination in perinatal brain injury, we hypothesize that extracellular membrane vesicles, the so-called exosomes, derived from WJ-MSC trigger oligodendroglial commitment and differentiation in endogenous neural progenitor cells (NPC) and OPC, respectively. Thus, the aim of this study is to investigate the potency of WJ-MSC-derived exosomes to promote oligodendroglial cell fate switch in NPC and differentiation in OPC. Methods: WJ-MSC-derived exosomes were isolated from culture supernatants by serial centrifugations. Exosome microRNA (miRNA) content was assessed by real-time PCR. After co-culture with WJ-MSC-derived exosomes, NPC and OPC-like MO3.13 cells were evaluated for the expression of markers involved in oligodendroglial specification and differentiation, respectively, by real-time PCR and Western Blot analysis. Results: miRNA that are involved in oligodendroglial cell fate switch and differentiation (e.g. miR-338) were present in WJ-MSC-derived exosomes. After 72 h of co-culture with exosomes, the expression of oligodendrogenic miR-338-3p (p<0.05) and miR-338-5p (p<0.05) were significantly increased in NPC. Furthermore, Notch signaling known to trigger oligodendroglial specification was activated in NPC, which was shown by the enhanced cleavage of Notch protein and the elevated transcription of the Notch target gene hairy and enhancer of split 1 (Hes1; p<0.05). The level of Let-7 miRNA (p<0.05), known to act through Notch to accelerate the generation of OPC from NPC, was increased in NPC after 72 h of co-culture with exosomes, as well. However, the transcription of the astrocyte marker glial fibrillary acidic protein (Gfap; p<0.05) and the neuronal cell fate factor neurogenic differentiation factor 1 (Neurod1; p<0.05) were significantly reduced. The co-culture of exosomes with MO3.13 for 5 days significantly increased the transcription of myelin basic protein (Mbp; p<0.05), a marker for mature oligodendrocytes. Conclusion: In conclusion, we have shown that isolated WJ-MSC-derived exosomes trigger NPC and OPC towards oligodendroglial differentiation, which seem to be partially ascribed to exosomal miR-338. Financial support by Gottfried and Julia Bangerter-Rhyner Foundation.