Mitochondrial Transfer from Bone Marrow Mesenchymal Stem Cells to Motor Neurons in Spinal Cord Injury Rats via Gap Junction

Abstract

Recent studies have demonstrated that bone marrow mesenchymal stem cells (BMSCs) protect the injured neurons of spinal cord injury (SCI) from apoptosis while the underlying mechanism of the protective effect of BMSCs remains unclear. In this study, we found the transfer of mitochondria from BMSCs to injured motor neurons and detected the functional improvement after transplanting. Methods: Primary rat BMSCs were co-cultured with oxygen-glucose deprivation (OGD) injured VSC4.1 motor neurons or primary cortical neurons. FACS analysis was used to detect the transfer of mitochondria from BMSCs to neurons. The bioenergetics profiling of neurons was detected by Extracellular Flux Analysis. Cell viability and apoptosis were also measured. BMSCs and isolated mitochondria were transplanted into SCI rats. TdT-mediated dUTP nick end labelling staining was used to detect apoptotic neurons in the ventral horn. Immunohistochemistry and Western blotting were used to measure protein expression. Re-myelination was examined by transmission electron microscope. BBB scores were used to assess locomotor function. Results: MitoTracker-Red labelled mitochondria of BMSCs could be transferred to the OGD injured neurons. The gap junction intercellular communication (GJIC) potentiator retinoid acid increased the quantity of mitochondria transfer from BMSCs to neurons, while GJIC inhibitor 18β glycyrrhetinic acid decreased mitochondria transfer. Internalization of mitochondria improved the bioenergetics profile, decreased apoptosis and promoted cell survival in post-OGD motor neurons. Furthermore, both transplantation of mitochondria and BMSCs to the injured spinal cord improved locomotor functional recovery in SCI rats. Conclusions: To our knowledge, this is the first evidence that BMSCs protect against SCI through GJIC to transfer mitochondrial to the injured neurons. Our findings suggested a new therapy strategy of mitochondria transfer for the patients with SCI.

Mechanisms underlying the protective effects of mesenchymal stem cell-based therapy

“…Accumulating evidence has shown that mitochondrial transfer occurs via TNTs, gap junctions, microvesicles, cell fusion and transfer of isolated mitochondria [132,[242][243][244][245]. So far, mitochondrial transfer from MSCs has demonstrated protective effects in lung injury, bronchial epithelial injury, allergic diseases, damaged cardiomyocytes, alkali-burnt corneal epithelial cells, kidney injury, ischemic damage, neurotoxicity, and spinal cord injury [132,[246][247][248][249][250][251][252][253]. Numerous studies have identified several signals including release of damaged mitochondria, mtDNA and mitochondrial products along with elevated ROS levels that trigger mitochondrial transfer from MSCs to the recipient cells [241].…”

“…Sinclair et al summarized different modes of intercellular communication and mitochondrial transfer by MSCs. Retinoic acid, a gap junction potentiator, greatly enhances the mitochondrial transfer efficiency from BM-MSCs to neurons, and this effect is partially abrogated by 18β glycyrrhetinic acid, which is a gap junction potentiator [253]. Inhibiting microtubule/TNTs, gap junction formation, or microvesicle endocytosis abrogates the transfer of cytoplasmic material from MSCs to epithelial cells [258].…”

Necrosulfonamide Ameliorates Neurological Impairment in Spinal Cord Injury by Improving Antioxidative Capacity

“…The phosphorylation of RIP3 then leads to activation of its substrate MLKL, and the phosphorylated MLKL regards as the activation of MLKL (Wang et al, 2018b). We examined the protective effects of NSA in oxygen-glucose deprivation (OGD)induced cell damage assay that replicates the pathological condition of SCI in vitro through RIP3 and MLKL activation (Wang et al, 2018b;Li et al, 2019;. We also examined the protective effects and the therapeutic window of NSA in SCI-mice.…”

Duraplasty of PHBV/PLA/Col membranes promotes axonal regeneration by inhibiting NLRP3 complex and M1 macrophage polarization in rats with spinal cord injury

“…A 10-g weight (#WH160162; Convergence Technology Co., Ltd, Shenzhen, China) was dropped from a height of 50 mm into the exposed spinal cord and the impounder was left for 20 seconds before being withdrawn to produce a moderate contusion in the SCI group, as described in our previous study. 31 The 60 animals that underwent decompressive durotomy were anesthetized again 4 hours after the initial injury, and the segment was reexposed. A durotomy with a 4-mm diameter was performed using microscissors under a dissecting microscope.…”