Mild hypothermia combined with a scaffold of NgR-silenced neural stem cells/Schwann cells to treat spinal cord injury

Schwann cell transplantation for remyelination, regeneration, tissue sparing, and functional recovery in spinal cord injury: A systematic review and meta-analysis of animal studies

INTRODUCTION

Spinal cord injury (SCI) is a significant global health challenge that results in profound physical and neurological impairments. Despite progress in medical care, the treatment options for SCI are still restricted and often focus on symptom management rather than promoting neural repair and functional recovery. This study focused on clarifying the impact of Schwann cell (SC) transplantation on the molecular, cellular, and functional basis of recovery in animal models of SCI.

MATERIAL AND METHODS

Relevant studies were identified by conducting searches across multiple databases, which included PubMed, Web of Science, Scopus, and ProQuest. The data were analyzed via comprehensive meta-analysis software. We assessed the risk of bias via the SYRCLE method.

RESULTS

The analysis included 59 studies, 48 of which provided quantitative data. The results revealed significant improvements in various outcome variables, including protein zero structures (SMD = 1.66, 95 %CI: 0.96-2.36; p < 0.001; I2 = 49.8 %), peripherally myelinated axons (SMD = 1.81, 95 %CI: 0.99-2.63; p < 0.001; I2 = 39.3 %), biotinylated dextran amine-labeled CST only rostral (SMD = 1.31, 95 % CI: 0.50-2.12, p < 0.01, I2 = 49.7 %), fast blue-labeled reticular formation (SMD = 0.96, 95 %CI: 0.43-1.49, p < 0.001, I2 = 0.0 %), 5-hydroxytryptamine caudally (SMD = 0.83, 95 %CI: 0.36-1.29, p < 0.001, I2 = 17.2 %) and epicenter (SMD = 0.85, 95 %CI: 0.17-1.53, p < 0.05, I2 = 62.7 %), tyrosine hydroxylase caudally (SMD = 1.86, 95 %CI: 1.14-2.59, p < 0.001, I2 = 0.0 %) and epicenter (SMD = 1.82, 95 %CI: 1.18-2.47, p < 0.001, I2 = 0.0 %), cavity volume (SMD = -2.07, 95 %CI: -2.90 - -1.24, p < 0.001, I2 = 67.2 %), and Basso, Beattie, and Bresnahan (SMD = 1.26, 95 %CI: 0.93-1.58; p < 0.001; I2 = 79.4 %).

CONCLUSIONS

This study demonstrates the promising potential of SC transplantation as a therapeutic approach for SCI, clarifying its impact on various biological processes critical for recovery.

Gene-Modified Stem Cells for Spinal Cord Injury: a Promising Better Alternative Therapy

Stem cell therapy holds great promise for the treatment of spinal cord injury (SCI), which can reverse neurodegeneration and promote tissue regeneration via its pluripotency and ability to secrete neurotrophic factors. Although various stem cell-based approaches have shown certain therapeutic effects when applied to the treatment of SCI, their clinical efficacies have been disappointing. Thus, it is an urgent need to further enhance the neurological benefits of stem cells through bioengineering strategies including genetic engineering. In this review, we summarize the progress of stem cell therapy for SCI and the prospect of genetically modified stem cells, focusing on the genome editing tools and functional molecules involved in SCI repair, trying to provide a deeper understanding of genetically modified stem cell therapy and more applicable clinical strategies for SCI repair.

Stem Cell Therapy for Spinal Cord Injury

Traumatic spinal cord injury (SCI) results in direct and indirect damage to neural tissues, which results in motor and sensory dysfunction, dystonia, and pathological reflex that ultimately lead to paraplegia or tetraplegia. A loss of cells, axon regeneration failure, and time-sensitive pathophysiology make tissue repair difficult. Despite various medical developments, there are currently no effective regenerative treatments. Stem cell therapy is a promising treatment for SCI due to its multiple targets and reactivity benefits. The present review focuses on SCI stem cell therapy, including bone marrow mesenchymal stem cells, umbilical mesenchymal stem cells, adipose-derived mesenchymal stem cells, neural stem cells, neural progenitor cells, embryonic stem cells, induced pluripotent stem cells, and extracellular vesicles. Each cell type targets certain features of SCI pathology and shows therapeutic effects via cell replacement, nutritional support, scaffolds, and immunomodulation mechanisms. However, many preclinical studies and a growing number of clinical trials found that single-cell treatments had only limited benefits for SCI. SCI damage is multifaceted, and there is a growing consensus that a combined treatment is needed.

Neuroprotection by Therapeutic Hypothermia

Hypothermia therapy is an old and important method of neuroprotection. Until now, many neurological diseases such as stroke, traumatic brain injury, intracranial pressure elevation, subarachnoid hemorrhage, spinal cord injury, hepatic encephalopathy, and neonatal peripartum encephalopathy have proven to be suppressed by therapeutic hypothermia. Beneficial effects of therapeutic hypothermia have also been discovered, and progress has been made toward improving the benefits of therapeutic hypothermia further through combination with other neuroprotective treatments and by probing the mechanism of hypothermia neuroprotection. In this review, we compare different hypothermia induction methods and provide a summarized account of the synergistic effect of hypothermia therapy with other neuroprotective treatments, along with an overview of hypothermia neuroprotection mechanisms and cold/hypothermia-induced proteins.

Polymer scaffolds facilitate spinal cord injury repair

During the past decades, improving patient neurological recovery following spinal cord injury (SCI) has remained a challenge. An effective treatment for SCI would not only reduce fractured elements and isolate developing local glial scars to promote axonal regeneration but also ameliorate secondary effects, including inflammation, apoptosis, and necrosis. Three-dimensional (3D) scaffolds provide a platform in which these mechanisms can be addressed in a controlled manner. Polymer scaffolds with favorable biocompatibility and appropriate mechanical properties have been engineered to minimize cicatrization, customize drug release, and ensure an unobstructed space to promote cell growth and differentiation. These properties make polymer scaffolds an important potential therapeutic platform. This review highlights the recent developments in polymer scaffolds for SCI engineering. STATEMENT OF SIGNIFICANCE: How to improve the efficacy of neurological recovery after spinal cord injury (SCI) is always a challenge. Tissue engineering provides a promising strategy for SCI repair, and scaffolds are one of the most important elements in addition to cells and inducing factors. The review highlights recent development and future prospects in polymer scaffolds for SCI therapy. The review will guide future studies by outlining the requirements and characteristics of polymer scaffold technologies employed against SCI. Additionally, the peculiar properties of polymer materials used in the therapeutic process of SCI also have guiding significance to other tissue engineering approaches.

Deferoxamine promotes recovery of traumatic spinal cord injury by inhibiting ferroptosis

Ferroptosis is an iron-dependent novel cell death pathway. Deferoxamine, a ferroptosis inhibitor, has been reported to promote spinal cord injury repair. It has yet to be clarified whether ferroptosis inhibition represents the mechanism of action of Deferoxamine on spinal cord injury recovery. A rat model of Deferoxamine at thoracic 10 segment was established using a modified Allen's method. Ninety 8-week-old female Wistar rats were used. Rats in the Deferoxamine group were intraperitoneally injected with 100 mg/kg Deferoxamine 30 minutes before injury. Simultaneously, the Sham and Deferoxamine groups served as controls. Drug administration was conducted for 7 consecutive days. The results were as follows: (1) Electron microscopy revealed shrunken mitochondria in the spinal cord injury group. (2) The Basso, Beattie and Bresnahan locomotor rating score showed that recovery of the hindlimb was remarkably better in the Deferoxamine group than in the spinal cord injury group. (3) The iron concentration was lower in the Deferoxamine group than in the spinal cord injury group after injury. (4) Western blot assay revealed that, compared with the spinal cord injury group, GPX4, xCT, and glutathione expression was markedly increased in the Deferoxamine group. (5) Real-time polymerase chain reaction revealed that, compared with the Deferoxamine group, mRNA levels of ferroptosis-related genes Acyl-CoA synthetase family member 2 (ACSF2) and iron-responsive element-binding protein 2 (IREB2) were up-regulated in the Deferoxamine group. (6) Deferoxamine increased survival of neurons and inhibited gliosis. These findings confirm that Deferoxamine can repair spinal cord injury by inhibiting ferroptosis. Targeting ferroptosis is therefore a promising therapeutic approach for spinal cord injury.

Polycaprolactone electrospun fiber scaffold loaded with iPSCs-NSCs and ASCs as a novel tissue engineering scaffold for the treatment of spinal cord injury

Background

Spinal cord injury (SCI) is a traumatic disease of the central nervous system, accompanied with high incidence and high disability rate. Tissue engineering scaffold can be used as therapeutic systems to provide effective repair for SCI.

Purpose

In this study, a novel tissue engineering scaffold has been synthesized in order to explore the effect of nerve repair on SCI.

Patients and methods

Polycaprolactone (PCL) scaffolds loaded with actived Schwann cells (ASCs) and induced pluripotent stem cells -derived neural stem cells (iPSC-NSCs), a combined cell transplantation strategy, were prepared and characterized. The cell-loaded PCL scaffolds were further utilized for the treatment of SCI in vivo. Histological observation, behavioral evaluation, Western-blot and qRT-PCR were used to investigate the nerve repair of Wistar rats after scaffold transplantation.

Results

The iPSCs displayed similar characteristics to embryonic stem cells and were efficiently differentiated into neural stem cells in vitro. The obtained PCL scaffolds werê0.5 mm in thickness with biocompatibility and biodegradability. SEM results indicated that the ASCs and (or) iPS-NSCs grew well on PCL scaffolds. Moreover, transplantation reduced the volume of lesion cavity and improved locomotor recovery of rats. In addition, the degree of spinal cord recovery and remodeling maybe closely related to nerve growth factor and glial cell-derived neurotrophic factor. In summary, our results demonstrated that tissue engineering scaffold treatment could increase tissue remodeling and could promote motor function recovery in a transection SCI model.

Conclusion

This study provides preliminary evidence for using tissue engineering scaffold as a clinically viable treatment for SCI in the future.

Chondroitin Sulfate Impairs Neural Stem Cell Migration Through ROCK Activation

Brain injuries such as trauma and stroke lead to glial scar formation by reactive astrocytes which produce and secret axonal outgrowth inhibitors. Chondroitin sulfate proteoglycans (CSPG) constitute a well-known class of extracellular matrix molecules produced at the glial scar and cause growth cone collapse. The CSPG glycosaminoglycan side chains composed of chondroitin sulfate (CS) are responsible for its inhibitory activity on neurite outgrowth and are dependent on RhoA activation. Here, we hypothesize that CSPG also impairs neural stem cell migration inhibiting their penetration into an injury site. We show that DCX+ neuroblasts do not penetrate a CSPG-rich injured area probably due to Nogo receptor activation and RhoA/ROCK signaling pathway as we demonstrate in vitro with neural stem cells cultured as neurospheres and pull-down for RhoA. Furthermore, CS-impaired cell migration in vitro induced the formation of large mature adhesions and altered cell protrusion dynamics. ROCK inhibition restored migration in vitro as well as decreased adhesion size.

Combinatorial Therapies After Spinal Cord Injury: How Can Biomaterials Help?

Traumatic spinal cord injury (SCI) results in an immediate loss of motor and sensory function below the injury site and is associated with a poor prognosis. The inhibitory environment that develops in response to the injury is mainly due to local expression of inhibitory factors, scarring and the formation of cystic cavitations, all of which limit the regenerative capacity of endogenous or transplanted cells. Strategies that demonstrate promising results induce a change in the microenvironment at- and around the lesion site to promote endogenous cell repair, including axonal regeneration or the integration of transplanted cells. To date, many of these strategies target only a single aspect of SCI; however, the multifaceted nature of SCI suggests that combinatorial strategies will likely be more effective. Biomaterials are a key component of combinatorial strategies, as they have the potential to deliver drugs locally over a prolonged period of time and aid in cell survival, integration and differentiation. Here we summarize the advantages and limitations of widely used strategies to promote recovery after injury and highlight recent research where biomaterials aided combinatorial strategies to overcome some of the barriers of spinal cord regeneration.

Biocompatibility of reduced graphene oxide nanoscaffolds following acute spinal cord injury in rats

Background:

Graphene has unique electrical, physical, and chemical properties that may have great potential as a bioscaffold for neuronal regeneration after spinal cord injury. These nanoscaffolds have previously been shown to be biocompatible in vitro; in the present study, we wished to evaluate its biocompatibility in an in vivo spinal cord injury model.

Methods:

Graphene nanoscaffolds were prepared by the mild chemical reduction of graphene oxide. Twenty Wistar rats (19 male and 1 female) underwent hemispinal cord transection at approximately the T2 level. To bridge the lesion, graphene nanoscaffolds with a hydrogel were implanted immediately after spinal cord transection. Control animals were treated with hydrogel matrix alone. Histologic evaluation was performed 3 months after the spinal cord transection to assess in vivo biocompatibility of graphene and to measure the ingrowth of tissue elements adjacent to the graphene nanoscaffold.

Results:

The graphene nanoscaffolds adhered well to the spinal cord tissue. There was no area of pseudocyst around the scaffolds suggestive of cytotoxicity. Instead, histological evaluation showed an ingrowth of connective tissue elements, blood vessels, neurofilaments, and Schwann cells around the graphene nanoscaffolds.

Conclusions:

Graphene is a nanomaterial that is biocompatible with neurons and may have significant biomedical application. It may provide a scaffold for the ingrowth of regenerating axons after spinal cord injury.