Intrathecal Acetyl-L-Carnitine Protects Tissue and Improves Function after a Mild Contusive Spinal Cord Injury in Rats

Elevated phagocytic capacity directs innate spinal cord repair

Immune cells elicit a continuum of transcriptional and functional states after spinal cord injury (SCI). In mammals, inefficient debris clearance and chronic inflammation impede recovery and overshadow pro-regenerative immune functions. We found that, unlike mammals, zebrafish SCI elicits transient immune activation and efficient debris clearance, without causing chronic inflammation. Single-cell transcriptomics and inducible genetic ablation showed zebrafish macrophages are highly phagocytic and required for regeneration. Cross-species comparisons between zebrafish and mammalian macrophages identified transcription and immune response regulator ( tcim ) as a macrophage-enriched zebrafish gene. Genetic deletion of zebrafish tcim impairs phagocytosis and regeneration, causes aberrant and chronic immune activation, and can be rescued by transplanting wild-type immune precursors into tcim mutants. Conversely, genetic expression of human TCIM accelerates debris clearance and regeneration by reprogramming myeloid precursors into activated phagocytes. This study establishes a central requirement for elevated phagocytic capacity to achieve innate spinal cord repair.

Domino reaction of neurovascular unit in neuropathic pain after spinal cord injury

The mechanism of neuropathic pain after spinal cord injury is complex, and the communication between neurons, glia, and blood vessels in neurovascular units significantly affects the occurrence and development of neuropathic pain. After spinal cord injury, a domino chain reaction occurs in the neuron-glia-vessel, which affects the permeability of the blood-spinal cord barrier and jointly promotes the development of neuroinflammation. This article discusses the signal transduction between neuro-glial-endothelial networks from a multidimensional point of view and reviews its role in neuropathic pain after spinal cord injury.

Comprehensive therapeutics targeting the corticospinal tract following spinal cord injury

Spinal cord injury (SCI), which is much in the public eye, is still a refractory disease compromising the well-being of both patients and society. In spite of there being many methods dealing with the lesion, there is still a deficiency in comprehensive strategies covering all facets of this damage. Further, we should also mention the structure called the corticospinal tract (CST) which plays a crucial role in the motor responses of organisms, and it will be the focal point of our attention. In this review, we discuss a variety of strategies targeting different dimensions following SCI and some treatments that are especially efficacious to the CST are emphasized. Over recent decades, researchers have developed many effective tactics involving five approaches: (1) tackle more extensive regions; (2) provide a regenerative microenvironment; (3) provide a glial microenvironment; (4) transplantation; and (5) other auxiliary methods, for instance, rehabilitation training and electrical stimulation. We review the basic knowledge on this disease and correlative treatments. In addition, some well-formulated perspectives and hypotheses have been delineated. We emphasize that such a multifaceted problem needs combinatorial approaches, and we analyze some discrepancies in past studies. Finally, for the future, we present numerous brand-new latent tactics which have great promise for curbing SCI.

Increased vascularization promotes functional recovery in the transected spinal cord rats by implanted vascular endothelial growth factor-targeting collagen scaffold

Spinal cord injury (SCI) is global health concern. The effective strategies for SCI are relevant to the improvement on nerve regeneration microenvironment. Vascular endothelial growth factor (VEGF) is an important cytokine for inducing angiogenesis and accelerating nerve system function recovery from injury. We proposed that VEGF could improve nerve regeneration in SCI. However, an uncontrolled delivery system target to injury site not only decreases the therapeutic efficacy but also increases the risk of tumor information. We implanted collagen scaffold (CS) targeted with a constructed protein, collagen-binding VEGF (CBD-VEGF), to bridge transected spine cord gap in a rat transected SCI model. Functional and histological examinations were conducted to assess the repair capacity of the delivery system CS/CBD-VEGF. The results indicated that the implantation of CS/CBD-VEGF into the model rats improved the survival rate and exerted beneficial effect on functional recovery. The controlled intervention improved the microenvironment, guided axon growth, and promoted neovascularization at the injury site. Therefore, the delivery system with stable binding of VEGF potentially provides a better therapeutic option for SCI. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1024-1034, 2018.

Nanofiber Scaffolds as Drug Delivery Systems to Bridge Spinal Cord Injury

The complex pathophysiology of spinal cord injury (SCI) may explain the current lack of an effective therapeutic approach for the regeneration of damaged neuronal cells and the recovery of motor functions. A primary mechanical injury in the spinal cord triggers a cascade of secondary events, which are involved in SCI instauration and progression. The aim of the present review is to provide an overview of the therapeutic neuro-protective and neuro-regenerative approaches, which involve the use of nanofibers as local drug delivery systems. Drugs released by nanofibers aim at preventing the cascade of secondary damage (neuro-protection), whereas nanofibrous structures are intended to re-establish neuronal connectivity through axonal sprouting (neuro-regeneration) promotion, in order to achieve a rapid functional recovery of spinal cord.

Reduced FAK-STAT3 signaling contributes to ER stress-induced mitochondrial dysfunction and death in endothelial cells

Excessive endoplasmic reticulum (ER) stress leads to cell loss in many diseases, e.g., contributing to endothelial cell loss after spinal cord injury. Here, we determined whether ER stress-induced mitochondrial dysfunction could be explained by interruption of the focal adhesion kinase (FAK)-mitochondrial STAT3 pathway we recently discovered. ER stress was induced in brain-derived mouse bEnd5 endothelial cells by thapsigargin or tunicamycin and caused apoptotic cell death over a 72h period. In concert, ER stress caused mitochondrial dysfunction as shown by reduced bioenergetic function, loss of mitochondrial membrane potential and increased mitophagy. ER stress caused a reduction in mitochondrial phosphorylated S727-STAT3, known to be important for maintaining mitochondrial function. Normal activation or phosphorylation of the upstream cytoplasmic FAK was also reduced, through mechanisms that involve tyrosine phosphatases and calcium signaling, as shown by pharmacological inhibitors, bisperoxovanadium (bpV) and 2-aminoethoxydiphenylborane (APB), respectively. APB mitigated the reduction in FAK and STAT3 phosphorylation, and improved endothelial cell survival caused by ER stress. Transfection of cells rendered null for STAT3 using CRISPR technology with STAT3 mutants confirmed the specific involvement of S727-STAT3 inhibition in ER stress-mediated cell loss. These data suggest that loss of FAK signaling during ER stress causes mitochondrial dysfunction by reducing the protective effects of mitochondrial STAT3, leading to endothelial cell death. We propose that stimulation of the FAK-STAT3 pathway is a novel therapeutic approach against pathological ER stress.