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.

We previously demonstrated that gene-modified umbilical cord blood mononuclear cells overexpressing a combination of recombinant neurotrophic factors are a promising therapeutic approach for cell-mediated gene therapy for neurodegenerative diseases, neurotrauma, and stroke. In this study, using a mini pig model of spinal cord injury, we proposed for the first time the use of gene-modified leucoconcentrate prepared from peripheral blood in the plastic blood bag for personalized ex vivo gene therapy. Leucoconcentrate obtained from mini pig peripheral blood was transduced with a chimeric adenoviral vector (Ad5/35F) that carried an enhanced green fluorescent protein (EGFP) reporter gene in the plastic blood bag. The day after blood donation, the mini pigs were subjected to moderate SCI and four hours post-surgery they were intravenously autoinfused with gene-modified leucoconcentrate. A week after gene-modified leucoconcentrate therapy, fluorescent microscopy revealed EGFP-expressing leucocytes in spinal cord at the site of contusion injury. In the spleen the groups of EGFP-positive cells located in the lymphoid follicles were observed. In vitro flow cytometry and fluorescent microscopy studies of the gene-modified leucoconcentrate samples also confirmed the production of EGFP by leucocytes. Thus, the efficacy of leucocytes transduction in the plastic blood bag and their migratory potential suggest their use for temporary production of recombinant biologically active molecules to correct certain pathological conditions. This paper presents a proof-of-concept of simple, safe and effective approach for personalized ex vivo gene therapy based on gene-modified leucoconcentrate autoinfusion. The animal protocols were approved by the Kazan State Medical University Animal Care and Use Committee (approval No. 5) on May 27, 2014.

Background: Pathological changes associated with spinal cord injury (SCI) can be observed distant, rostral, or caudal to the epicenter of injury. These remote areas represent important therapeutic targets for post-traumatic spinal cord repair. The present study aimed to investigate the following in relation to SCI: distant changes in the spinal cord, peripheral nerve, and muscles. Methods: The changes in the spinal cord, the tibial nerve, and the hind limb muscles were evaluated in control SCI animals and after intravenous infusion of autologous leucoconcentrate enriched with genes encoding neuroprotective factors (VEGF, GDNF, and NCAM), which previously demonstrated a positive effect on post-traumatic restoration. Results: Two months after thoracic contusion in the treated mini pigs, a positive remodeling of the macro- and microglial cells, expression of PSD95 and Chat in the lumbar spinal cord, and preservation of the number and morphological characteristics of the myelinated fibers in the tibial nerve were observed and were aligned with hind limb motor recovery and reduced soleus muscle atrophy. Conclusion: Here, we show the positive effect of autologous genetically enriched leucoconcentrate-producing recombinant neuroprotective factors on targets distant to the primary lesion site in mini pigs with SCI. These findings open new perspectives for the therapy of SCI.

Currently, the treatments for spinal cord injury are limited. Gene therapy is one of the most promising approaches aimed at overcoming negative post-traumatic consequences in the spinal cord. Numerous studies performed in rodents indicate a positive effect of the delivery of therapeutic genes to the spinal cord to stimulate neuroregeneration. However, to bring the developed protocols of gene therapy to the stage of clinical trials, it is necessary to verify the results obtained in experiments on large laboratory animals. Objective: Immunofluorescence analysis of the response of markers of cell stress and apoptosis, synaptic proteins and neuroglia in the spinal cord of female vietnamese pot-bellied pigs after intrathecal delivery of genes encoding vascular endothelial growth factor (VEGF165), glial-derived neurotrophic factor and neuronal cell adhesion molecule (NCAM1), using human umbilical cord blood mononuclear cells (UCBMC). In experimental pigs (n = 2), 4 hours after modeling a dosed contusion injury of the spinal cord at the Th8-Th9 level, 2х106 genetically modified UCBMCs overexpressing recombinant VEGF, GDNF, and NCAM molecules in 200 |jl of saline were intrathecally injected. Control animals (n = 2) were injected with 200 jl of saline into the cerebrospinal fluid. Intact pigs (n = 2) were used to obtain baseline values for immunofluorescence analysis of post-traumatic molecular and cellular responses. After 60 days, immunofluorescence analysis in the rostral and caudal parts of the spinal cord relative to the epicenter of injury revealed positive changes in experimental pigs against the background of cell-mediated delivery of the VeGf165, GDNF, and NCAM1 genes. In the anterior horns of the rostral and caudal spinal cord of animals from the therapeutic group, a higher level of fluorescence of the synaptic protein synaptophysin, a lower number of astrocytes and microglial cells were found, which may indicate functional recovery of neurons and suppression of the development of astrogliosis. In the rostral section, in the area of the corticospinal tract, gene therapy maintained the number of oligodendrocytes, which ensure myelination of regenerating axons. The results obtained suggest that genetically modified UCBMCs, overexpressing recombinant molecules VEGF and GDNF (as therapeutic molecules) and NCAM (as a molecule providing survival and targeted targeting of cell carriers), contribute to post-traumatic regeneration of the spinal cord.

Neural networks disturbed due to spinal cord injury are capable to restore that is largely determined by post-traumatic remodeling. It is known that information exchange between neurons is carried out by electrical impulse, which ensures the transmission of excitation in synapses, that is realized through neurotrophic factors according to the concept of neurotrophic interactions. Objective: to study the effect of a combination of epidural electrostimulation above and below the site of neurotrauma during training on the treadmill and intrathecal administration of human umbilical cord blood mononuclear cells, which simultaneously delivered three therapeutic genes encoding vascular endothelial growth factor (VEGF165), glial neurotrophic factor (GDNF) and neuronal cell adhesion molecule (NCAM1), to post-traumatic reorganization of neuroglia cells in a model of dosed concussion injury of rat spinal cord at the Th8-Th9 level. 30 days after the simulation of neurotrauma by the immunofluorescence method, a change in the number of macro- and microglia cells in the segment caudal from the damage epicenter was revealed. Electrostimulation did not affect the number of GFAP+-cells in the gray matter, but the combined effect of gene and electrotherapy restrained the increase in their number. Differences were found in the reactions of astrocytes in white and gray matter in response to electrical stimulation. In the zones of gray matter, the supporting effect of the combination of gene and electrotherapy on the number of Olig2+-cells was most clearly manifested. In this group of animals, the inhibition of the increase in the number of Iba1+-microglia cells in the gray matter can also be interpreted as a positive factor contributing to neuroregeneration.