Improvement of sensory neuron growth and survival via negatively regulating PTEN by miR-21-5p-contained small extracellular vesicles from skin precursor-derived Schwann cells

Meng Cong,Yan Li,Qianru He,Mi Shen,Xia Wu,Fei Ding,Haiyan Shi,Liting Wang

doi:10.1186/s13287-020-02125-4

Abstract

BackgroundPatients with peripheral nerve injury (PNI) often suffer from hypoxic ischemic impairments, in particular when combined with vascular damage, causing neuronal dysfunction and death. Increasing attention has been paid on skin precursor-derived Schwann cells (SKP-SCs), and previous study has shown that SKP-SCs could promote sensory recovery after cell therapy for PNI, resembling the effect of naive SCs, and SKP-SC-derived extracellular vesicles (SKP-SC-EVs) are putatively supposed to be promising therapeutic agents for neural regeneration.MethodsSKPs were induced to differentiate towards SCs with cocktail factors (N2, neuregulin-1β, and forskolin) in vitro. SKP-SC-EVs were isolated by exoEasy Maxi Kit and characterized by morphology and phenotypic markers of EVs. Rat sensory neurons from dorsal root ganglions (DRGs) were primarily cultured in regular condition or exposed to oxygen-glucose-deprivation (OGD) condition. SKP-SC-EVs were applied to DRGs or sensory neurons, with LY294002 (a PI3K inhibitor) added; the effect on neurite outgrowth and cell survival was observed. Moreover, microRNA (miR) candidate contained in SKP-SC-EVs was screened out, and miR-mimics were transfected into DRG neurons; meanwhile, the negative regulation of PTEN/PI3K/Akt axis and downstream signaling molecules were determined.ResultsIt was shown that SKP-SC-EVs could improve the neurite outgrowth of DRGs and sensory neurons. Furthermore, SKP-SC-EVs enhanced the survival of sensory neurons after OGD exposure by alleviating neuronal apoptosis and strengthening cell viability, and the expression of GAP43 (a neuron functional protein) in neurons was upregulated. Moreover, the neuro-reparative role of SKP-SC-EVs was implicated in the activation of PI3K/Akt, mTOR, and p70S6k, as well as the reduction of Bax/Bcl-2 ratio, that was compromised by LY294002 to some extent. In addition, transferring miR-21-5p mimics into sensory neurons could partly protect them from OGD-induced impairment.ConclusionsSum up, SKP-SC-EVs could improve neurite outgrowth of DRG sensory neurons in physiological and pathological condition. Moreover, the in vitro therapeutic potential of SKP-SC-EVs on the survival and restoration of OGD-injured sensory neurons was evidenced to be associated with miR-21-5p contained in the small EVs and miR-21-5p/PTEN/PI3K/Akt axis.Graphic abstract

Highlights

Patients with peripheral nerve injury (PNI) often suffer from hypoxic ischemic impairments, in particular when combined with vascular damage, causing neuronal dysfunction and death
The results from Nanoparticle tracking analysis (NTA) demonstrated that the average diameter of these vesicles was 140.5 nm and the main peak of the particle size was located at 148.9 nm, and the concentration was Promotion of Dorsal root ganglion (DRG) axonal outgrowth by Skin precursor (SKP)-Schwann cell (SC)-Extracellular vesicle (EV) We evaluated whether skin precursor-derived Schwann cells (SKP-SCs)-EVs could affect axonal outgrowth
Results from this study indicated that the internalization of SKP-SC-EVs could potentiate the neurite extension of regularly cultured sensory neurons, and the neurite regrowth and cell survival of OGD-injured sensory neurons

Summary

Introduction

Patients with peripheral nerve injury (PNI) often suffer from hypoxic ischemic impairments, in particular when combined with vascular damage, causing neuronal dysfunction and death. Schwann cells (SCs) have been considered as supporting glial cells for neurons, facilitating the physiological process of neuro-regeneration spontaneously after mild nerve injury [1, 2]; the problems of poor regeneration may be attributed to the lack of abundant endogenous SCs and sufficient response, resulting in neurological dysfunction after severe nerve damage [3, 4]. Neural crest stem/precursor cells from postnatal bone marrow, dental pulp, and skin show desirable potential to generate Schwann-like cell [7]. In vivo neural crest cells give rise to SCs; focus on Schwann-like cells from reliable neural crest cell source for neuroprotection and neuro-regeneration is a significant work

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