Extracellular vesicles from skin precursor-derived Schwann cells promote axonal outgrowth and regeneration of motoneurons via Akt/mTOR/p70S6K pathway

Abstract

Background: Skin precursor-derived Schwann cells (SKP-SCs) have been shown to benefit the recovery of spinal cord injury (SCI) and peripheral nerve injury (PNI) with motor dysfunction. However, the effect of extracellular vesicles (EVs) from SKP-SCs responsible for neuroregeneration remains unknown.Methods: Based on the obtainment and identification of rat SKP-SCs and their derived EVs, the primary rat injury model of motoneurons resulting from axotomy in vitro or nerve crush in vivo, as well as the secondary rat ischemic hypoxic injury model of motoneuron exposure to oxygen-glucose-deprivation (OGD) in vitro, were treated with EVs from skin precursor-derived Schwann cells (SKP-SC-EVs), respectively.Then, the axonal outgrowth and regrowth was observed and compared, and cell viability as well as the protein kinase B/mammalian target of rapamycin/p70 S6 kinase (Akt/mTOR/p70S6K) signaling pathway was detected, moreover, rapamycin (an mTOR inhibitor) was used to further reveal the underlying molecular mechanism.Results: The internalization of SKP-SC-EVs by neuronal cells was identified in vitro and in vivo. Besides the pro-axonal outgrowth effect of SKP-SC-EVs, prospectively, the treatment of OGD-injured motoneurons with SKP-SC-EVs potentiated the restoration of neuronal viability and axonal regrowth. Furthermore, the axotomizing injury could be improved with SKP-SC-EVs treatment in vitro and in vivo. Finally, it was shown that the application of SKP-SC-EVs could activate the Akt/mTOR/p70S6K signaling pathway that can be abolished by rapamycin.Conclusions: In summary, the addition of SKP-SC-EVs could regulate the cell growth and death signaling pathway mediated by Akt/mTOR/p70S6K, owing to the transmission of cargos in EVs to damaged motoneurons, which leads to axonal regrowth and neuronal resurrection. Thus, SKP-SC-EVs treatment could be a novel promising strategy for improving the axonal outgrowth and regeneration of motoneurons.

SKP-SC-EVs Mitigate Denervated Muscle Atrophy by Inhibiting Oxidative Stress and Inflammation and Improving Microcirculation

“…We previously confirmed that SKP-SC-EVs promote the axonal growth of the sciatic nerve [ 40 ]. A nerve graft constructed from SKP-SC-EVs can repair peripheral nerve defects [ 41 ].…”

“…Previous studies have shown that SKP-SCs have an effect similar to that of primary SCs, such as the promotion of the functional recovery of nerve cells after treatment. SKP-SC-EVs have potential comparable to that of SKP-SCs and can significantly enhance the regeneration and recovery of damaged nerve cells [ 40 , 56 ]. In addition, we sequenced and analyzed SKP-SC-EVs in our previous study and found that they contained abundant miRNAs with antioxidant and anti-inflammatory effects, including miR-30a-5p, miR-22, miRNA-23a, and miR-27a/b.…”

“…SKPs were isolated from the skin tissues of newborn Sprague-Dawley rats and induced to differentiate into SKP-SCs as described above [ 40 ]. SKP-SCs were grown on culture dishes coated with 0.02 mg/mL laminin (Corning Inc., Brooklyn, NY, USA) and 0.2 mg/mL poly-D-lysine (Sigma-Aldrich, St. Louis, MO, USA) within DMEM/F-12 (3:1) (Corning) containing 2% N2 supplement (Stem Cell Technologies, Vancouver, BC, Canada), 50 ng/mL heregulin-1β (R&D, MN, USA), 5 μM forskolin (Sigma-Aldrich, St. Louis, MO, USA), 3% fetal bovine serum (FBS; Gibco, Carlsbad, CA, USA), and 1% penicillin/streptomycin (Beyotime, Shanghai, China).…”

Extracellular Vesicles: Emerging Therapeutics in Cutaneous Lesions

“…Previous research showed that SKP-SC-EVs could not only promote axonal regrowth and motoneuronal regeneration via the Akt/mTOR/p70S6K pathway but also improve the growth and survival of sensory neurons via the PTEN/PI3K/Akt axis. 23 , 24 …”

“…Previous research showed that SKP-SC-EVs could not only promote axonal regrowth and motoneuronal regeneration via the Akt/mTOR/p70S6K pathway but also improve the growth and survival of sensory neurons via the PTEN/PI3K/Akt axis. 23,24 EVs can also be isolated from all body fluids, including blood, 25 breast milk, 26 urine, 27 saliva 28 and cerebral spinal fluid. 29 And viruses, bacteria, parasites and fungi release EVs in the process of infection.…”