GSE159814
Umbilical Mesenchymal Stem Cell-derived Exosomes Facilitate Spinal Cord Functional Recovery Through miR-199a-3p/145-5p mediated NGF/TrkA Signaling Pathway in Rats
Background:  Though exosomes, as the by-products of human umbilical cord mesenchymal stem cells (hUC-MSCs), have been demonstrated to be an effective therapy for traumatic spinal cord injury (SCI), it remains unclear through which manner exosomes act.  Aim:    In order to figure out whether exosomes attenuate lesion size of SCI by the amelioration of neuronal injury triggered by secondary inflammatory storm and induction of inner motivation of neurite outgrowth, we designed and performed this experiment.   Methods:   We determined absolute contents of all exosomal miRNAs and investigated the potential mechanisms of miR-199a-3p/145-5p in inducing neurite outgrowth in vivo and vitro.  Results:  miR-199a-3p/145-5p, which were relatively top-ranking miRNAs in exosomes, promoted PC12 cells differentiation suppressed by lipopolysaccharide (LPS) in vitro through the modulation of NGF/TrkA pathway. We also demonstrated that Cblb was the direct target of miR-199a-3p and Cbl was the direct target of miR-145-5p. Cblb and Cbl genes knock down revealed that TrkA ubiquitylation level significantly decreased, subsequently, activating the NGF/TrkA downstream pathways Akt and Erk. In return, overexpression of Cblb and Cbl suggested that TrkA ubiquitylation level significantly increased, subsequently, inactivating the NGF/TrkA downstream pathways Akt and Erk. Western blot and co-immunoprecipitation confirmed the direct interaction between TrkA and Cblb, TrkA and Cbl. In vivo experiment, exosomal miR-199a-3p/145-5p were found to up-regulate TrkA expression in the lesion site and promote locomotor function of SCI rats as well.  Conclusion:  In summary, our study suggested that hUC-MSCs derived exosomes may treat SCI by transferring miR-199a-3p/145-5p to neurons, and modulating TrkA ubiquitylation, and strengthening the NGF/TrkA signaling pathway in SCI rats. Overall design: Three samples from exosomes derived from non-treated human umbilical cord mesenchymal stem cells