Spinal cord injury pharmacotherapy: Current research & development and competitive commercial landscape as of 2015

Traumatic Human Spinal Cord Injury: Are Single Treatments Enough to Solve the Problem?

Traumatic spinal cord injury (SCI) results in partial or complete motor deficits, such as paraplegia, tetraplegia, and sphincter control, as well as sensory disturbances and autonomic dysregulation such as arterial hypotension, lack of sweating, and alterations in skin lability. All this has a strong psychological impact on the affected person and his/her family, as well as costs to healthcare institutions with an economic burden in the short, medium, and long terms. Despite at least forty years of experimental animal studies and several clinical trials with different therapeutic strategies, effective therapy is not universally accepted. Most of the published works on acute and chronic injury use a single treatment, such as medication, trophic factor, transplant of a cell type, and so on, to block some secondary injury mechanisms or promote some mechanisms of structural/functional restoration. However, despite significant results in experimental models, the outcome is a moderate improvement in muscle strength, sensation, or eventually in sphincter control, which has been considered non-significant in human clinical trials. Here we present a brief compilation of successful individual treatments that have been applied to secondary mechanisms of action. These studies show limited neuroprotective or neurorestorative approaches in animal models and clinical trials. Thus, the few benefits achieved so far represent a rationale to further explore other strategies that seek better structural and functional restoration of the injured spinal cord.

Research on Differentiation of Bone Marrow Stromal Cells (BMSCs) Prompted by MicroRNA-124 and Effect on Inflammatory Reaction of Spinal Cord Injury Nerve Cells

The major feature of spinal cord injury (SCI) was the damage of nervous tissue in spinal cord. The damaged spinal cord was difficult to be repaired and regenerated. MicroRNA-124 could play a role in the repairing and recovering the injured tissue. The BMSCs could participate in repairing the damage. However, the regulatory effect of MicroRNA-124 on BMSCs and the inflammatory response of SCI was still not illustrated. These spinal cord nerve cells were assigned into group of mechanical damage, BMSCs and BMSCs with miR-124 overexpression followed by analysis of proliferation of nerve cells by MTT assay, apoptotic activity, expression of miR-124, GFAP and BDNF by Real time PCR, levels of TNF-α and IL-6 by ELISA as well as MDH and SOD activity. miR-124 mimics transfection significantly promoted BMSCs proliferation and increased ALK activity and the expression of GFAP and BDNF. In conclusion, the proliferation and differentiation of BMSCs could be regulated by miR-124. The inflammation and oxidative stress could be restrained so as to prompt the proliferation and repair of SCI cells and restrain apoptosis, indicating that it might be beneficial to recover the SCI.

Bone Marrow Mesenchymal Stem Cells (BMSCs) Promote Neuronal Cell Repair in Spinal Cord Injury by Regulating Toll-Like Receptor 4/Nuclear Factor-Kappa B Signaling Pathway

SCI (SCI) poses a challenge to nerve cell repair strategies. SCI injury can lead to the development of inflammation, which in turn can exacerbate nerve cell damage. The TLR4/NF-kappa B signaling pathway is a common inflammatory signaling pathway. Since BMSCs are involved in injury repair, whether they can promote the repair of SCI neuronal cells have not been reported. Spinal cord nerve cells were cultured in vitro and divided into mechanical injury group and BMSCs group followed by analysis of cell proliferation activity and detection of altered apoptotic activity. Changes in the concentrations of IL-6 and IL-1β were measured by ELISA and cellular mitochondrial alterations was assessed by JG-B staining along with analysis of NF-kappa B, TLR4, related neurodevelopmental factor BDNF, and NGF expression by western blot. Mechanical damage to neuronal cells resulted in decreased cell proliferation, increased apoptotic activity, decreased cellular mitochondrial activity, increased TLR4 and NF-kappa B expression, decreased BDNF and NGF expression, as well as increased secertions of IL-6 and IL-1β (P < 0.05). In contrast, co-culture with BMSCs resulted in increased proliferation and decreased apoptosis of mechanically injured neuronal cells, increased cellular mitochondrial activity, with observation of the inverse changes in other factors (P < 0.05). In conclusion, BMSCs can suppress inflammation and promote repair of injured neuronal cells by inhibiting TLR4/NF-kappa B signaling.

Induction of Neurogenesis and Angiogenesis in a Rat Hemisection Spinal Cord Injury Model With Combined Neural Stem Cell, Endothelial Progenitor Cell, and Biomimetic Hydrogel Matrix Therapy

Acute spinal cord injury is a devastating injury that may lead to loss of independent function. Stem-cell therapies have shown promise; however, a clinically efficacious stem-cell therapy has yet to be developed. Functionally, endothelial progenitor cells induce angiogenesis, and neural stem cells induce neurogenesis. In this study, we explored using a multimodal therapy combining endothelial progenitor cells with neural stem cells encapsulated in a bioactive biomimetic hydrogel matrix to facilitate stem cell-induced neurogenesis and angiogenesis in a rat hemisection spinal cord injury model.

DESIGN

Laboratory experimentation.

SETTING

University laboratory.

SUBJECTS

Female Fischer 344 rats.

INTERVENTIONS

Three groups of rats: 1) control, 2) biomimetic hydrogel therapy, and 3) combined neural stem cell, endothelial progenitor cell, biomimetic hydrogel therapy underwent right-sided spinal cord hemisection at T9-T10. The blinded Basso, Beattie, and Bresnahan motor score was obtained weekly; after 4 weeks, observational histologic analysis of the injured spinal cords was completed.

MEASUREMENTS AND MAIN RESULTS

Blinded Basso, Beattie, and Bresnahan motor score of the hind limb revealed significantly improved motor function in rats treated with combined neural stem cell, endothelial progenitor cell, and biomimetic hydrogel therapy (p < 0.05) compared with the control group. The acellular biomimetic hydrogel group did not demonstrate a significant improvement in motor function compared with the control group. Immunohistochemistry evaluation of the injured spinal cords demonstrated de novo neurogenesis and angiogenesis in the combined neural stem cell, endothelial progenitor cell, and biomimetic hydrogel therapy group, whereas, in the control group, a gap or scar was found in the injured spinal cord.

CONCLUSIONS

This study demonstrates proof of concept that multimodal therapy with endothelial progenitor cells and neural stem cells combined with a bioactive biomimetic hydrogel can be used to induce de novo CNS tissue in an injured rat spinal cord.

Human Pluripotent Stem Cells for Spinal Cord Injury

Spinal cord injury (SCI) as a serious public health issue and neurological insult is one of the most severe cause of long-term disability. To date, a variety of techniques have been widely developed to treat central nervous system injury. Currently, clinical treatments are limited to surgical decompression and pharmacotherapy. Because of their negative effects and inefficiency, novel therapeutic approaches are required in the management of SCI. Improvement and innovation of stem cell-based therapies have a huge potential for biological and future clinical applications. Human pluripotent stem cells (hPSCs) including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are defined by their abilities to divide asymmetrically, self-renew and ultimately differentiate into various cell lineages. There are considerable research efforts to use various types of stem cells, such as ESCs, neural stem cells (NSCs), and mesenchymal stem cells (MSCs) in the treatment of patients with SCI. Moreover, the use of patient-specific iPSCs holds great potential as an unlimited cell source for generating in vivo models of SCI. In this review, we focused on the potential of hPSCs in treating SCI.

Evaluating accessibility of intravenously administered nanoparticles at the lesion site in rat and pig contusion models of spinal cord injury

In spinal cord injury (SCI), timely therapeutic intervention is critical to inhibit the post-injury rapidly progressing degeneration of spinal cord. Towards that objective, we determined the accessibility of intravenously administered biodegradable nanoparticles (NPs) as a drug delivery system to the lesion site in rat and pig contusion models of SCI. Poly (d,l-lactide co-glycolide, PLGA)-based NPs loaded with a near-infrared dye as a marker for NPs were used. To analyze and quantify localization of NPs to the lesion site, we mapped the entire spinal cord, segment-by-segment, for the signal count. Our objectives were to determine the NP dose effect and duration of retention of NPs at the lesion site, and the time window post-SCI within which NPs localize at the lesion site. We hypothesized that breakdown of the blood-spinal cord barrier following contusion injury could lead to more specific localization of NPs at the lesion site. The mapping data showed a dose-dependent increase and significantly greater localization of NPs at the lesion site than in the remaining uninjured segment of the spinal cord. Further, NPs were seen to be retained at the lesion site for more than a week. With delayed post-SCI administration, localization of NPs at the lesion site was reduced but still localize even at four weeks post-injury administration. Interestingly, in uninjured animals (sham control), greater accumulation of NPs was seen in the thoracic and lumbar enlargement regions of the spinal cord, which in animals with SCI changed to the lesion site, indicating drastic post-injury hemodynamic changes in the spinal cord. Similar to the rat results, pig contusion model of SCI showed greater NP localization at the lesion site. In conclusion, NPs could potentially be explored as a carrier for delivery of therapeutics to the lesion site to minimize the impact of post-SCI response.

MANF attenuates neuronal apoptosis and promotes behavioral recovery via Akt/MDM-2/p53 pathway after traumatic spinal cord injury in rats

The aim of this study was to investigate the potential effect and mechanism of action of MANF in attenuating neuronal apoptosis following t-SCI. A clip compressive model was used to induce a crush injury of the spinal cord in a total of 230 rats. The Basso, Beattie, and Bresnahan (BBB) score, spinal cord water content, and blood spinal cord barrier (BSCB) permeability were evaluated. The expression levels of MANF and its downstream proteins were examined by western blotting. Immunofluorescence staining of MANF, NeuN, GFAP, Iba-1, cleaved caspase-3, and TUNEL staining were also performed. Cells were counted in six randomly selected fields in the gray matter regions of the sections from two spinal cord sites (2 mm rostral and caudal to the epicenter of the injury) per sample. A cell-based mechanical injury model was also conducted using SH-SY5Y cells. Cell apoptosis and viability were assessed by flow cytometry, an MTT assay, and trypan blue staining. Subcellular structures were observed by transmission electron microscopy. MANF was mainly expressed in neurons. The expression levels of MANF, and its downstream target, p-Akt, were gradually increased and after t-SCI. Treatment with MANF increased Bcl-2 and decreased Bax and CC-3 levels; these effects were reversed on treatment with MK2206. The BBB score, spinal cord water content, and BSCB destruction were also ameliorated by MANF treatment. MANF decreases neuronal apoptosis and improves neurological function through Akt/MDM-2/p53 pathway after t-SCI. Therefore, MANF might be a potential treatment for patients with t-SCI.© 2018 BioFactors, 2018.