Gingiva-Derived Mesenchymal Stem Cell-Extracellular Vesicles Activate Schwann Cell Repair Phenotype and Promote Nerve Regeneration

Abstract

A fully functional recovery of peripheral nerve injury remains a major challenge and an unmet clinical need. Recent evidence has reported promising therapeutic effects of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) in experimental models of tissue injuries and inflammatory diseases, but less is known about their effects on peripheral nerve regeneration. In this study, we investigated the effects of gingiva-derived mesenchymal stem cell (GMSC)-derived EVs on peripheral nerve regeneration of crush-injured mice sciatic nerves. In vivo studies mimicking clinical nerve repair showed that locally wrapping Gelfoam embedded with GMSC-derived EVs at the crush injury site promoted functional recovery and axonal regeneration, which were comparable with effects conferred by direct transplantation of GMSCs. Mechanistically, we showed that GMSC-derived EVs promoted proliferation and migration of Schwann cells, upregulated the protein expressions of c-JUN, Notch1, GFAP (glial fibrillary acidic protein), and SRY (sex determining region Y)-box 2 (SOX2), characteristic genes of dedifferentiation or repair phenotype of Schwann cells, through which pharmacologically blocking c-JUN/JNK (c-JUN N-terminal kinase) activity significantly abrogated GMSC-derived EV-induced upregulation of these Schwann cell dedifferentiation/repair phenotype-related genes. These findings suggest that GMSC-derived EVs promote peripheral nerve regeneration possibly by activating c-JUNgoverned repair phenotype of Schwann cells.

Dental Stem Cell-Derived Secretome/Conditioned Medium: The Future for Regenerative Therapeutic Applications

“…Various investigations suggested that gingival MSC-derived EXs, EVs, or CM could represent novel therapeutic interventions in managing peripheral nerve injury [168,169], motor neuron injury [170], and skin [171] and bone defects [172]. The results were comparable with effects conferred by direct transplantation of gingival MSCs [168,169]. The regenerative effect of EXs derived from human gingival MSCs combined with biodegradable chitin conduits on peripheral nerve injury was investigated.…”

“…In an in vitro study, the gingival MSCs derived EVs embedded on locally wrapping gel-foam proved to exert beneficial effects on the functional recovery and axonal repair/regeneration of the crush-injured sciatic nerve in mice. The gingival MSC-EVs robustly upregulated the expression of several repair Schwann cell-related genes c-JUN, Notch1, GFAP, and SOX-2, significantly blocking the activity of c-JUN/N-terminal kinase (c-JUN/JNK), which normally abolishes the upregulation of Schwann cell repair genes [168]. The neuroprotective capability of human gingival MSC-CM on scratch-injured motor-neuron-like NSC-34 cells was evolved by suppressing apoptotic markers (cleaved caspase-3 and Bax), oxidative stress markers (superoxide dismutase-(SOD-) 1, iNOS), while upregulating anti-inflammatory cytokine (IL-10) and neurotrophic factor (BDNF and NT-3) expressions.…”

“…This finding represents an auspicious application potential for tongue reconstruction in patients suffering from tongue cancer. All these studies propose gingival MSCs' secretome/CM as a simple and autologous therapeutic tool to repair/regenerate nerve injuries, mainly through increasing the expression of anti-inflammatory cytokines (IL-10), antiapoptotic cytokine (Bcl2) [170], and markers denoting neural growth (BDGF, NT-3, Neurofilament 200, S100) [168][169][170]173], as well as enhancing proliferation and regeneration of nerve cells detected by PCNA [168], CCK-8 [169], and Shh [173] aside from a suppression of proinflammatory cytokine TNF-α [170], IL-17, IFN-γ [175,176], and proapoptotic (Bax and cleaved caspase-3) and oxidative stress markers (SOD-1, iNOS, COX-2) [170]. (Table 2).…”

Stem‐cell–based therapies to enhance peripheral nerve regeneration

“…In light of the practical limitations associated with SCs, there has been growing enthusiasm for the use of both precursor and stem cell–based therapies (we use the term “stem cell” throughout this review to maintain consistency while recognizing that few of the cell sources mentioned are true stem cells) for peripheral nerve regeneration . We are also cognizant of the fact that embryonic stem cells generally have a higher regenerative capacity and are less lineage committed than adult precursor and/or stem cells .…”

“…based therapies (we use the term "stem cell" throughout this review to maintain consistency while recognizing that few of the cell sources mentioned are true stem cells) for peripheral nerve regeneration. [26][27][28][29] We are also cognizant of the fact that embryonic stem cells generally have a higher regenerative capacity and are less lineage committed than adult precursor and/or stem cells. 30,31 There is a growing body of evidence in preclinical animal studies showing that stem cells play a positive role in the regeneration of peripheral nerves after injury.…”