Delivery of Basic Fibroblast Growth Factor Through an In Situ Forming Smart Hydrogel Activates Autophagy in Schwann Cells and Improves Facial Nerves Generation via the PAK-1 Signaling Pathway

Study on the Role and Mechanism of Exosomes Derived from Dental Pulp Stem Cells in Promoting Regeneration of Myelin Sheath in Rats with Sciatic Nerve Injury

The prognosis of peripheral nerve injury (PNI) is usually poor, and currently, there is no effective treatment for PNI. Studies have shown that exosomes derived from mesenchymal stem cells could promote nerve regeneration by optimizing the function of endogenous Schwann cells (SCs), while the mechanism is unclear. Autophagy, a highly conserved intracellular catabolic process responsible for maintaining cellular homeostasis, has been proved to be involved in the regulation of nerve repair after injury. We explored the effect of exosomes derived from dental pulp stem cells (DPSC-Exos) on the regeneration of myelin sheath in rats with sciatic nerve injury (SNI). In vitro and in vivo experiments were performed to clarify whether the effect of DPSC-Exos is associated with autophagy of SCs and to reveal the mechanism at the molecular level. Our results showed that the SCs of SNI rats exhibited the obvious autophagic characteristics, and the increase of P53 expression was an internal factor of autophagy. Our mechanism research indicated that DPSC-Exos could deliver miR-122-5p from DPSCs into SCs and suppressed the rapamycin (RAPA)-induced autophagy in SCs by inhibiting P53 expression. Rescue experiments showed that both the use of GW4869 and overexpression of exogenous P53 in SCs could reverse the inhibitory effect of DPSCs on the autophagy in SCs from co-culture system. In short, our study indicated that DPSC-Exos could promote the regeneration of the myelin sheath through suppressing the autophagy in SCs caused by PNI via miR-122-5p/P53 pathway; this provides researchers with another option for precise repair of PNI.

Growth Factors to Enhance Nerve Regeneration: Approaching Clinical Translation

Following nerve injury, growth factors (GFs) are transiently upregulated in injured neurons, proliferating Schwann cells, and denervated muscle and skin. They act on these same cells and tissues to promote nerve regeneration and end-organ reinnervation. Consequently, much attention has been focused on developing GF-based therapeutics. A major barrier to clinical translation of GFs is their short half-life. To provide sustained GF treatment to the affected nerve, muscle, and skin in a safe and practical manner, engineered drug delivery systems are needed. This review highlights recent advancements in GF-based therapeutics and discusses the remaining hurdles for clinical translation.

Induction of Autophagy and Its Role in Peripheral Nerve Regeneration after Peripheral Nerve Injury

No matter what treatment is used after nerve transection, a complete cure is impossible, so basic and clinical research is underway to find a cure. As part of this research, autophagy is being investigated for its role in nerve regeneration. Here, we review the existing literature regarding the involvement and significance of autophagy in peripheral nerve injury and regeneration. A comprehensive literature review was conducted to assess the induction and role of autophagy in peripheral nerve injury and subsequent regeneration. Studies were included if they were prospective or retrospective investigations of autophagy and facial or peripheral nerves. Articles not mentioning autophagy or the facial or peripheral nerves, review articles, off-topic articles, and those not written in English were excluded. A total of 14 peripheral nerve studies that met these criteria, including 11 involving sciatic nerves, 2 involving facial nerves, and 1 involving the inferior alveolar nerve, were included in this review. Studies conducted on rats and mice have demonstrated activation of autophagy and expression of related factors in peripheral nerves with or without stimulation of autophagy-inducing factors such as rapamycin, curcumin, three-dimensional melatonin nerve scaffolds, CXCL12, resveratrol, nerve growth factor, lentinan, adipose-derived stem cells and melatonin, basic fibroblast growth factor, and epothilone B. Among the most studied of these factors in relation to degeneration and regeneration of facial and sciatic nerves are LC3II/I, PI3K, mTOR, Beclin-1, ATG3, ATG5, ATG7, ATG9, and ATG12. This analysis indicates that autophagy is involved in the process of nerve regeneration following facial and sciatic nerve damage. Inadequate autophagy induction or failure of autophagy responses can result in regeneration issues after peripheral nerve damage. Animal studies suggest that autophagy plays an important role in peripheral nerve degeneration and regeneration.

Central Facial Nervous System Biomolecules Involved in Peripheral Facial Nerve Injury Responses and Potential Therapeutic Strategies

Peripheral facial nerve injury leads to changes in the expression of various neuroactive substances that affect nerve cell damage, survival, growth, and regeneration. In the case of peripheral facial nerve damage, the injury directly affects the peripheral nerves and induces changes in the central nervous system (CNS) through various factors, but the substances involved in these changes in the CNS are not well understood. The objective of this review is to investigate the biomolecules involved in peripheral facial nerve damage so as to gain insight into the mechanisms and limitations of targeting the CNS after such damage and identify potential facial nerve treatment strategies. To this end, we searched PubMed using keywords and exclusion criteria and selected 29 eligible experimental studies. Our analysis summarizes basic experimental studies on changes in the CNS following peripheral facial nerve damage, focusing on biomolecules that increase or decrease in the CNS and/or those involved in the damage, and reviews various approaches for treating facial nerve injury. By establishing the biomolecules in the CNS that change after peripheral nerve damage, we can expect to identify factors that play an important role in functional recovery from facial nerve damage. Accordingly, this review could represent a significant step toward developing treatment strategies for peripheral facial palsy.

The application of collagen in the repair of peripheral nerve defect

Collagen is a natural polymer expressed in the extracellular matrix of the peripheral nervous system. It has become increasingly crucial in peripheral nerve reconstruction as it was involved in regulating Schwann cell behaviors, maintaining peripheral nerve functions during peripheral nerve development, and being strongly upregulated after nerve injury to promote peripheral nerve regeneration. Moreover, its biological properties, such as low immunogenicity, excellent biocompatibility, and biodegradability make it a suitable biomaterial for peripheral nerve repair. Collagen provides a suitable microenvironment to support Schwann cells’ growth, proliferation, and migration, thereby improving the regeneration and functional recovery of peripheral nerves. This review aims to summarize the characteristics of collagen as a biomaterial, analyze its role in peripheral nerve regeneration, and provide a detailed overview of the recent advances concerning the optimization of collagen nerve conduits in terms of physical properties and structure, as well as the application of the combination with the bioactive component in peripheral nerve regeneration.

Mechanism underlying linezolid-induced peripheral neuropathy in multidrug-resistant tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) remains a main global health concern as there is no comprehensive therapeutic intervention yet and numerous adverse effects follow the therapeutic process. In recent years, linezolid has been frequently used for treating MDR-TB. However, peripheral neuropathy associated with linezolid has reduced patient compliance. The current study explored the mechanism underlying linezolid-induced peripheral neuropathy in MDR-TB. Autophagy plays a neuroprotective role against peripheral nerve injury. We hypothesized that autophagy might also play a neuroprotective role against linezolid-induced peripheral neuropathy. In this study, we collected 12 questionnaires from MDR-TB patients in our hospital, and 10 of them developed linezolid-induced pain. The pain is mainly concentrated in the feet and accompanied by numbness. Subsequently, we used Sprague-Dawley (SD) rats and Schwann cells (SCs) to explore the mechanism. We found that linezolid causes a sparse arrangement of sciatic nerve tissue with associated loss of neurons, myelin sheaths, and down-regulation of LC3B expression. These results were also confirmed by in vitro experiments, showing that linezolid inhibited the proliferation of SCs. And the expression of P-AKT and P62 was elevated, and the expression of LC3B declined compared with the control group. Moreover, chloroquine (CQ), an autophagy inhibitor, also exhibited experimental results similar to linezolid. In summary, we conclude that linezolid-induced peripheral neuropathy is associated with the inhibition of autophagy flux.