Allogenic bone marrow-derived mesenchymal stem cells and its conditioned media for repairing acute and sub-acute peripheral nerve injuries in a rabbit model

The Role of Macrophages in Nerve Regeneration: Polarization and Combination with Tissue Engineering

Peripheral nerve regeneration after trauma poses a substantial clinical challenge that has already been investigated for many years. Infiltration of immune cells is a critical step in the response to nerve damage that creates a supportive microenvironment for regeneration. In this work, we focus on a special type of immune cell, macrophage, in addressing the problem of neuronal regeneration. We discuss the complex endogenous mechanisms of peripheral nerve injury and regrowth vis-à-vis macrophages, including their recruitment, polarization, and interplay with Schwann cells post-trauma. Furthermore, we elucidate the underlying mechanisms by which exogenous stimuli govern the above events. Finally, we summarize the necessary roles of macrophages in peripheral nerve lesions and reconstruction. There are many challenges in controlling macrophage functions to achieve complete neuronal regeneration, even though considerable progress has been made in understanding the connection between these cells and peripheral nerve damage.

LncRNA MALAT1 facilitates BM-MSCs differentiation into endothelial cells and ameliorates erectile dysfunction via the miR-206/CDC42/PAK1/paxillin signalling axis

BACKGROUND

Erectile dysfunction (ED) is a common male sexual dysfunction, with an increasing incidence, and the current treatment is often ineffective.

METHODS

Vascular endothelial growth factor (VEGFA) was used to treat bone marrow-derived mesenchymal stem cells (BM-MSCs), and their cell migration rates were determined by Transwell assays. The expression of the von Willebrand Factor (vWF)VE-cadherin, and endothelial nitric oxide synthase(eNOS) endothelial markers was determined by qRT‒PCR and Western blot analyses. The MALAT1-induced differentiation of BM-MCs to ECs via the CDC42/PAK1/paxillin pathway was explored by transfecting VEGFA-induced BM-MSC with si-MALAT1 and overexpressing CDC42 and PAK1. The binding capacity between CDC42, PAK1, and paxillin in VEGFA-treated and non-VEGFA-treated BM-MSCs was examined by protein immunoprecipitation. MiR-206 was overexpressed in VEGFA-induced BM-MSC, and the binding sites of MALAT1, miR-206, and CDC42 were identified using a luciferase assay. Sixty male Sprague‒Dawley rats were divided into six groups (n = 10/group). DMED modelling was demonstrated by APO experiments and was assessed by measuring blood glucose levels. Erectile function was assessed by measuring the intracavernosa pressure (ICP) and mean arterial pressure (MAP). Penile erectile tissue was analysed by qRT‒PCR, Western blot analysis, and immunohistochemical staining.

RESULTS

MALAT1 under VEGFA treatment conditions regulates the differentiation of BM-MSCs into ECs by modulating the CDC42/PAK1/paxillin axis. In vitro experiments demonstrated that interference with CDC42 and MALAT1 expression inhibited the differentiation of BM-MSCs to ECs. CDC42 binds to PAK1, and PAK1 binds to paxillin. In addition, CDC42 in the VEGFA group had a greater ability to bind to PAK1, whereas PAK1 in the VEGFA group had a greater ability to bind to paxillin. Overexpression of miR-206 in VEGFA-induced BM-MSCs demonstrated that MALAT1 competes with the CDC42 3'-UTR for binding to miR-206, which in turn is involved in the differentiation of BM-MSCs to ECs. Compared to the DMED model group, the ICP/MAP ratio was significantly greater in the three BM-MSCs treatment groups.

CONCLUSIONS

MALAT1 facilitates BM-MSC differentiation into ECs by regulating the miR-206/CDC42/PAK1/paxillin axis to improve ED. The present findings revealed the vital role of MALAT1 in the repair of BM-MSCs for erectile function and provided new mechanistic insights into the BM-MSC-mediated repair of DMED.

Adipose-derived stem cells modified by TWIST1 silencing accelerates rat sciatic nerve repair and functional recovery

The regeneration of peripheral nerves after injury is often slow and impaired, which may be associated with weakened and denervated muscles subsequently leading to atrophy. Adipose-derived stem cells (ADSCs) are often regarded as cell-based therapeutic candidate due to their regenerative potential. The study aims to assess the therapeutic efficacy of gene-modified ADSCs on sciatic nerve injury. We lentivirally transduced ADSCs with shRNA-TWIST1 and transplanted modified cells to rats undergoing sciatic nerve transection and repair. Results showed that TWIST1 knockdown accelerated functional recovery of rats with sciatic nerve injury as faster nerve conduction velocity and higher wire hang scores obtained by rats transplanted with TWIST1-silenced ADSCs than scramble ADSCs. Although the rats experienced degenerated axons and decreased myelin sheath thickness after sciatic nerve injury 8 weeks after operation, those transplanted with TWIST1-silenced ADSCs exhibited more signs of regenerated nerve fibers surrounded by newly formed myelin sheaths than those with scramble ADSCs. The rats transplanted with TWIST1-silenced ADSCs presented increased expressions of neurotrophic factors including neurotrophin-3 (NT-3), brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and glial cell line-derived neurotrophic factor (GDNF) in the sciatic nerves than those with scramble ADSCs. These results suggest that genetically modifying TWIST1 in ADSCs could facilitate peripheral nerve repair after injury in a more efficient way than that with ADSCs alone.

Mesenchymal stem cells' "garbage bags" at work: Treating radial nerve injury with mesenchymal stem cell-derived exosomes

Unlike central nervous system injuries, peripheral nerve injuries (PNIs) are often characterized by more or less successful axonal regeneration. However, structural and functional recovery is a senile process involving multifaceted cellular and molecular processes. The contemporary treatment options are limited, with surgical intervention as the gold-standard method; however, each treatment option has its associated limitations, especially when the injury is severe with a large gap. Recent advancements in cell-based therapy and cell-free therapy approaches using stem cell-derived soluble and insoluble components of the cell secretome are fast-emerging therapeutic approaches to treating acute and chronic PNI. The recent pilot study is a leap forward in the field, which is expected to pave the way for more enormous, systematic, and well-designed clinical trials to assess the therapeutic efficacy of mesenchymal stem cell-derived exosomes as a bio-drug either alone or as part of a combinatorial approach, in an attempt synergize the best of novel treatment approaches to address the complexity of the neural repair and regeneration.

Preemptive administration of mesenchymal stem cells-derived conditioned medium can attenuate the development of neuropathic pain in rats via downregulation of proinflammatory cytokines

Neuropathic pain (NP) is a chronic condition characterized by persistent pain following nerve injury. It is a challenging clinical problem to manage due to limited treatment options. Mesenchymal stem cells (MSCs)-derived conditioned medium (CM) is a cell-free product that contains the secretome of MSCs and has been shown to have therapeutic potential in various inflammatory and degenerative disorders. Several animal studies have examined the antinociceptive effects of MSCs-CM on established neuropathic pain, but none have investigated the early prevention of neuropathic pain using MSCs-CM. Therefore, in this study, we tested whether preemptive administration of MSCs-CM could attenuate the development of NP in rats. To this end, NP was induced in Wistar rats using a chronic constriction injury (CCI) model (day 0), and then the animals were divided into four groups: Sham, CCI, CCI-Dulbecco's Modified Eagle Medium (DMEM), and CCI-CM. The CCI-CM group received 1 ml intraperitoneal administration of MSCs-CM on days - 1, 1, and 2, while the Sham, CCI, and CCI-DMEM groups received vehicle only (normal saline or DMEM). Mechanical withdrawal threshold and thermal withdrawal latency were assessed to evaluate pain sensitivities. In addition, the expression levels of proinflammatory cytokines (TNF-α and IL-1β) in the spinal cord tissues were measured using quantitative real-time PCR (qRT-PCR). The results demonstrated that preemptive treatment with MSCs-CM can significantly attenuate the development of NP, as evidenced by improved mechanical withdrawal threshold and thermal withdrawal latency in the CCI-CM group compared to the CCI and CCI-DMEM groups. Furthermore, the relative gene expression of proinflammatory cytokines TNF-α and IL-1β were significantly decreased in the spinal cord tissues of the CCI-CM group compared to the control groups. These findings suggest that preemptive administration of MSCs-CM can attenuate the development of NP in rats, partly due to the downregulation of proinflammatory cytokines.

Mesenchymal stem cells derived from bone marrow and adipose tissue for repairing acute sciatic nerve injury in a rabbit model

Peripheral nerve injury is one of the common disabling clinical conditions and around 50% of the cases end up in permanent impairment. Due to the lack of effective treatment options regenerative medicine employing stem cells is being evaluated. The presented study evaluated and compared regeneration potential of mesenchymal stem cells (MSCs) derived from bone marrow (BM) and adipose tissue (AD) in acute rabbit sciatic nerve injury (axonotmesis) model. A total of n = 54 grey giant rabbits were made subject of the study and divided equally into 3 groups: Control, BM-MSCs in Collagen I and AD-MSCs in Collagen I as per the treatment given. Iliac crest BM and omental AD was harvested from the same donor for isolation and culture of MSCs. The repair of sciatic nerve injury was evaluated on days 60 and 90. The clinical and histopathological scores and SEM morphology was better in cell treated groups as compared to the control. Morphology and histological studies revealed injured nerve in different levels of regenerative process. Gene expression was more than double for N-Cadherin in cell treated groups as compared to the control, especially at day 60. Between cell treated groups, BM-MSCs group showed better response as compared to the AD-MSCs, although statistically non-significant (p > 0.05). Incomplete nerve regeneration observed under various diagnostic parameters was in compliance to the incomplete clinical recovery at day 90. It was concluded that MSCs may improve sciatic nerve healing but fall short of complete regeneration at day 90, although BM-MSCs may have an edge over AD-MSCs.