The translation of new therapies for spinal cord injury to clinical trials can be facilitated with large animal models close in morpho-physiological scale to humans. Here, we report functional restoration and morphological reorganization after spinal contusion in pigs, following a combined treatment of locomotor training facilitated with epidural electrical stimulation (EES) and cell-mediated triple gene therapy with umbilical cord blood mononuclear cells overexpressing recombinant vascular endothelial growth factor, glial-derived neurotrophic factor, and neural cell adhesion molecule. Preliminary results obtained on a small sample of pigs 2 months after spinal contusion revealed the difference in post-traumatic spinal cord outcomes in control and treated animals. In treated pigs, motor performance was enabled by EES and the corresponding morpho-functional changes in hind limb skeletal muscles were accompanied by the reorganization of the glial cell, the reaction of stress cell, and synaptic proteins. Our data demonstrate effects of combined EES-facilitated motor training and cell-mediated triple gene therapy after spinal contusion in large animals, informing a background for further animal studies and clinical translation.

Recent findings from multimodal imaging studies point to macrostructural pathological changes in areas significantly distant from the epicenter of spinal cord injury, both in the spinal cord and in the brain. Studies are being performed to determine cellular and molecular mechanisms of these shifts, which are currently poorly understood. Research has demonstrated that the pathological process in the remote area is multifaceted. This process involves astrocytes and microglia, which contribute to the degeneration of nerve fibers passing from and through the immediate impact area, as well as participate in reciprocal activation. As a result, there is accompanying synaptic loss in areas remote to the spinal cord injury location. Reactive astrocytes produce chondroitin sulfate proteoglycans that inhibit axon growth and damage cells. However, neuronal death in the remote area remains controversial. The area of primary injury is the source of numerous neurotoxic molecules that release into the cerebrospinal fluid. It is assumed that these molecules, primarily matrix metalloproteinases, disrupt the blood-spinal cord barrier, which leads to tissue infiltration by macrophage precursors in the remote area. Activated macrophages secrete pro-inflammatory cytokines and matrix metalloproteinases, which, in turn, induce astrocytes and microglia towards a pro-inflammatory phenotype. In addition, reactive microglia, together with astrocytes, secrete numerous pro-inflammatory and neurotoxic molecules that activate inflammatory signaling pathways, consequently exacerbating synaptic depletion and neurological deterioration. It appears likely that the interplay between chronic inflammation and neurodegeneration is a pivotal characteristic of the pathological process in the spinal cord areas distant from the epicenter of the lesion. Pathological changes in the distant areas should be the object of research as potential therapeutic targets.

Spinal cord injury (SCI) presents a complex challenge in neurorehabilitation, demanding innovative therapeutic strategies to facilitate functional recovery. This study investigates the effects of treadmill training on SCI recovery, emphasizing motor function enhancement, neural tissue preservation, and axonal growth. Our research, conducted on a rat model, demonstrates that controlled treadmill exercises significantly improve motor functions post-SCI, as evidenced by improved scores on the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale and enhanced electromyography readings. Notably, the training facilitates the preservation of spinal cord tissue, effectively reducing secondary damage and promoting the maintenance of neural fibers in the injured area. A key finding is the significant stimulation of axonal growth around the injury epicenter in trained rats, marked by increased growth-associated protein 43 (GAP43) expression. Despite these advancements, the study notes a limited impact of treadmill training on motoneuron adaptation and highlights minimal changes in the astrocyte and neuron–glial antigen 2 (NG2) response. This suggests that, while treadmill training is instrumental in functional improvements post-SCI, its influence on certain neural cell types and glial populations is constrained.

In this study, the effects of different combinations of the genes Vegf, Ang, and Gdnf injected both using direct virus-mediated injection (adenovirus, Ad5) and umbilical cord blood mononuclear cells (UCBCs) on the processes of stimulation of post-ischemic innervation, angiogenesis, and regeneration in skeletal muscle were investigated in a rat hindlimb chronic ischemia model. It was shown that more pronounced stimulation of angiogenesis and restoration of post-ischemic innervation were achieved both in the early (28 days post-ischemia, dpi) and late (42 dpi) terms of the experiment in the calf muscle when UCBCs delivered the combination of Ad5-Vegf and Ad5-Ang compared to the direct injection of the same vector combination into the area of ischemia. At the same time, the inclusion of Ad5-Gdnf in the combination of Ad5-Vegf and Ad5-Ang directly injected or administered by UCBCs provided a significant increase in the number of centronuclear muscle fibers, indicating stimulation of post-ischemic reparative myogenesis. This study allowed us to determine the most effective gene combinations for angiogenesis and neurogenesis, which, in the future, may serve as the basis for the development of gene and gene cell products for the treatment of chronic lower limb ischemia.

Objective. To analyze the mechanisms of the blood-spinal cord barrier permeability violation after spinal cord injury and to assess its impact on the development of secondary injuries, including those in the areas significantly remote from the epicenter of injury.Material and Methods. The article is an analysis of 45 publications supplemented by our own experimental data. The search for articles was conducted in databases such as PubMed, Scopus and Web of Science on the topic under study. Experimental data were obtained using confocal microscopy and bioluminescence detection on a rat spinal cord contusion injury model.Results. The problem of barrier disintegration in a region remote from the injury epicenter is considered. It is shown that spinal cord injury significantly increases the permeability of the blood-spinal cord barrier, which promotes enhanced transmigration of immune cells and release of cytotoxic molecules. The results of our own studies on a model of dosed contusion injury in the thoracic spinal cord of a rat show that the permeability of the barrier increases not only in the injury epicenter, but also along the entire length of the organ. This circumstance is especially significant for the lumbar spinal cord, where neural networks that are critical for the maintenance and restoration of motor function are localized.Conclusion. Potential causes of remote barrier disruption have been discussed, including the possible influence of damage biomarker molecules that travel from the injury epicenter to remote regions of the spinal cord via the bloodstream or cerebrospinal fluid. The promising clinical application of effective experimental approaches to contain barrier disruption and restore the blood-spinal cord barrier and the lack of translational research in this direction are highlighted.