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Regenerative capability of the peripheral nervous system after injury is enhanced by Schwann cells (Scs)producing several growth factors. the clinical use of Scs in nerve regeneration strategies is hindered by the necessity of removing a healthy nerve to obtain the therapeutic cells. Adipose-derived stem cells (ASCs) can be chemically differentiated towards a SC-like phenotype (dASCs), and represent a promising alternative to Scs. their physiology can be further modulated pharmacologically by targeting receptors for neurotransmitters such as acetylcholine (ACh). In this study, we compare the ability of rat dASCs and native SCs to produce NGF in vitro. We also evaluate the ability of muscarinic receptors, in particular the M2 subtype, to modulate NGF production and maturation from the precursor (proNGF) to the mature (mNGF) form. For the first time, we demonstrate that dASCs produce higher basal levels of proNGF and mature NGF compared to SCs. Moreover, muscarinic receptor activation, and in particular M2 subtype stimulation, modulates NGF production and maturation in both SCs and dASCs. Indeed, both cell types express both proNGF A and B isoforms, as well as mNGF. After M2 receptor stimulation, proNGF-B (25 kDa), which is involved in apoptotic processes, is strongly reduced at transcript and protein level. Thus, we demonstrate that dASCs possess a stronger neurotrophic potential compared to SCs. ACh, via M2 muscarinic receptors, contributes to the modulation and maturation of NGF, improving the regenerative properties of dASCs.Neurotrophins are a group of proteins that specifically stimulate neuronal activity during development, adult life and injury, supporting neuron survival, neurite outgrowth and controlling neuron and glial cell differentiation 1 .Nerve growth factor (NGF) has particular relevance for the survival and functional activity of sensory and sympathetic neurons 2,3 . NGF is synthesised as a precursor (proNGF) which is proteolytically cleaved to produce mature NGF (mNGF) 3,4 . In particular, two different isoforms of proNGF are described: proNGF-A (32 kDa) and proNGF-B (25 kDa) 5 . There are consistent clues that proNGF-A isoform may act as a modulator of cell survival 6 , whereas proNGF-B isoform acts as an apoptotic signal 7 . proNGF undergoes post-translational intracellular and extracellular processing at both amino-and carboxyl-terminal ends, thanks to the action of plasmin cleavage, to produce the mNGF form of 13.2kDa 4 . Both proNGF and mNGF can be secreted and have active functional roles 5,7,8 . In healthy peripheral nerves, NGF is produced by the target organs and retrogradely transported to the neuronal soma 1 binding two distinct receptors: the high-affinity Tropomyosin receptor kinase A (TrkA) and the low-affinity p75NTR 9,10 . After nerve injury, axons are dissociated from the source of neurotrophic support, and the Schwann cells (SCs) lose their contact with the axons before acquiring the repair phenotype. At this stage, open Scientific RepoRtS | (2020) 10:7159 | https://doi.org/10.1...

No abstract

Due to the microenvironment created by Schwann cell (SC) activity, peripheral nerve fibers are able to regenerate. Inflammation is the first response to nerve damage and the removal of cellular and myelin debris is essential in preventing the persistence of the local inflammation that may negatively affect nerve regeneration. Acetylcholine (ACh) is one of the neurotransmitters involved in the modulation of inflammation through the activity of its receptors, belonging to both the muscarinic and nicotinic classes. In this report, we evaluated the expression of α7 nicotinic acetylcholine receptors (nAChRs) in rat sciatic nerve, particularly in SCs, after peripheral nerve injury. α7 nAChRs are absent in sciatic nerve immediately after dissection, but their expression is significantly enhanced in SCs after 24 h in cultured sciatic nerve segments or in the presence of the proinflammatory neuropeptide Bradykinin (BK). Moreover, we found that activation of α7 nAChRs with the selective partial agonist ICH3 causes a decreased expression of c-Jun and an upregulation of uPA, MMP2 and MMP9 activity. In addition, ICH3 treatment inhibits IL-6 transcript level expression as well as the cytokine release. These results suggest that ACh, probably released from regenerating axons or by SC themselves, may actively promote through α7 nAChRs activation an anti-inflammatory microenvironment that contributes to better improving the peripheral nerve regeneration.

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