Regeneration of Spinal Cord Connectivity Through Stem Cell Transplantation and Biomaterial Scaffolds

Therapeutic potential of flavonoids in neuroprotection: brain and spinal cord injury focus

Flavonoids in fruits, vegetables, and plant-based drinks have potential neuroprotective properties, with clinical research focusing on their role in reducing oxidative stress, controlling inflammation, and preventing apoptosis. Some flavonoids, such as quercetin, kaempferol, fisetin, apigenin, luteolin, chrysin, baicalein, catechin, epigallocatechin gallate, naringenin, naringin, hesperetin, genistein, rutin, silymarin, and daidzein, have been presented to help heal damage to the central nervous system by affecting key signaling pathways including PI3K/Akt and NF-κB. This review systematically analyzed articles on flavonoids, neuroprotection, and brain and spinal cord injury from primary medical databases like Scopus, PubMed, and Web of Science. Flavonoids enhance antioxidant defenses, reduce pro-inflammatory cytokine production, and aid cell survival and repair by focusing on specific molecular pathways. Clinical trials are also exploring the application of preclinical results to therapeutic approaches for patients with spinal cord injury and traumatic brain injury. Flavonoids can enhance injury healing, reduce lesion size, and enhance synaptic plasticity and neurogenesis. The full potential of flavonoids lies in their bioavailability, dose, and administration methods, but there are still challenges to overcome. This review explores flavonoid-induced neuroprotection, its clinical implications, future research opportunities, and molecular mechanisms, highlighting the potential for innovative CNS injury therapies and improved patient health outcomes.

Mechanism of effect and therapeutic potential of NLRP3 inflammasome in spinal cord injury

Spinal cord injury (SCI) is a serious and disabling central nervous system injury that can trigger various neuropathological conditions, resulting in neuronal damage and release of various pro-inflammatory mediators, leading to neurological dysfunction. Currently, surgical decompression, drugs and rehabilitation are primarily used to relieve symptoms and improve endogenous repair mechanisms; however, they cannot directly promote nerve regeneration and functional recovery. SCI can be divided into primary and secondary injuries. Secondary injury is key to determining the severity of injury, whereas inflammation and cell death are important pathological mechanisms in the process of secondary SCI. The activation of the inflammasome complex is thought to be a necessary step in neuro-inflammation and a key trigger for neuronal death. The NLRP3 inflammasome is a cytoplasmic multiprotein complex that is considered an important factor in the development of SCI. Once the NLRP3 inflammasome is activated after SCI, NLRP3 nucleates the assembly of an inflammasome, leading to caspase 1-mediated proteolytic activation of the interleukin-1β (IL-1β) family of cytokines, and induces an inflammatory, pyroptotic cell death. Inhibition of inflammasomes can effectively inhibit inflammation and cell death in the body and promote the recovery of nerve function after SCI. Therefore, inhibition of NLRP3 inflammasome activation may be a promising approach for the treatment of SCI. In this review, we describe the current understanding of NLRP3 inflammasome activation in SCI pathogenesis and its subsequent impact on SCI and summarize drugs and other potential inhibitors based on NLRP3 inflammasome regulation. The objective of this study was to emphasize the role of the NLRP3 inflammasome in SCI, and provide a new therapeutic strategy and theoretical basis for targeting the NLRP3 inflammasome as a therapy for SCI.

Hybrid hydrogels containing gradients in gold nanoparticles for localized delivery of mesenchymal stem cells and enhanced nerve tissues remodeling in vivo

Currently, most peripheral nerve injuries are incurable mainly due to excessive reactive oxygen species (ROS) generation in inflammatory tissues, which can further exacerbate localized tissue injury and cause chronic diseases. Although promising for promoting nerve regeneration, stem cell therapy still suffers from abundant intrinsic limitations, mainly including excessive ROS in lesions and inefficient production of growth factors (GFs). Biomaterials that scavenge endogenous ROS and promote GFs secretion might overcome such limitations and thus are being increasingly investigated. Herein, firstly reported as specific ROS scavenging agents and paracrine stimulators, gold nanoparticles (GNPs) were incorporated in the chitosan/polyvinyl alcohol hydrogel networks. The GNPs/hydrogel composite can support the survival of mesenchymal stem cells (MSCs) with excellent expansion efficiency and protect MSCs in a simulated ROS microenvironment, decreasing the intracellular ROS levels and simultaneously enhancing cell viability. Moreover, biodegradable scaffolds, along with MSCs, were implanted into sciatic nerve defects in a rat model to show good application value in vivo. Our work demonstrated that the GNPs/hydrogel shows great promise in MSCs therapy for peripheral nerve injury with convincing biological evidence.

Unidirectional and sustainable release of NGF and BDNF from a chitosan gel-mediated multilayer ordered composite membrane in promoting both spinal cord and sciatic nerve injury repair

To develop a scaffold suitable for simultaneous repair of both spinal cord injury (SCI) and sciatic nerve injury (SNI), we designed a multilayer composite membrane capable of unidirectional and sustained release of two factors: nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). The membrane's morphology, mechanical properties, cytocompatibility, drug release kinetics, swelling, and degradation behavior were thoroughly characterized. Additionally, its ability to promote the differentiation of PC-12 cells was assessed. The findings indicated that the composite membrane featured a tri-layered structure and exhibited robust mechanical strength, enabling it to protect and regulate the release of NGF and BDNF. This regulation ensured the appropriate timing and concentration of the factors necessary for cell differentiation and growth. Moreover, the membrane demonstrated excellent cell compatibility and significantly fostered the differentiation of PC-12 cells into axons. In rat models of SCI and SNI, the composite membrane markedly enhanced axon and neuron regeneration, myelination, neural stem cell proliferation, and nerve fiber clustering, while reducing astrocyte formation. It also improved the integrity of spinal cord tissue and motor function recovery, suggesting that this scaffold holds promise for the repair of both SCI and SNI.

A bibliometric analysis of the top 100 most cited articles on corticospinal tract regeneration from 2004 to 2024

Objective

Here, bibliometric and visual analytical techniques were employed to assess the key features of the 100 most cited publications concerning corticospinal tract (CST) regeneration.

Methods

Research was conducted within the Web of Science Core Collection to pinpoint the 100 most cited publications on CST regeneration. From these, comprehensive data encompassing titles, authorship, key terms, publication venues, release timelines, geographic origins, and institutional affiliations were extracted, followed by an in-depth bibliometric examination.

Results

The 100 most cited publications were all published between 2004 and 2024. These seminal papers amassed an aggregate of 18,321 citations, with individual citation counts ranging from 83 to 871 and a median of 136 citations per paper. Schwab M. E., stood out as the most prominent contributor, with significant authorship in 9 of the 100 papers. The United States dominated the geographical distribution, accounting for 49 of the articles. With 17 publications, the University of California System led the institutional rankings. A thorough keyword analysis revealed pivotal themes in the field, encompassing the optic nerve, gene expression, CST integrity and regeneration, diffusion tensor imaging, myelin-associated glycoproteins, inhibitors of neurite outgrowth, and methods of electrical and intracortical microstimulation.

Conclusion

This investigation provides a bibliometric analysis of CST regeneration, underscoring the significant contribution of the United States to this field. Our findings unveiled the dynamics and trends within the field of CST regeneration, providing a scientific foundation for advancing clinical applications. Building on this analysis, the clinical application of CST regeneration should be optimized through interdisciplinary collaboration, enabling the exploration and validation of a variety of therapeutic approaches, including the use of neurotrophic factors, stem cell therapies, biomaterials, and electrical stimulation. Concurrently, additional clinical trials are necessary to test the safety and efficacy of these therapeutic methods and develop assessment tools for monitoring the recovery of patients. Furthermore, rehabilitation strategies should be refined, and professional education and training should be provided to enhance the understanding of CST regeneration treatments among both medical professionals and patients. The implementation of these strategies promises to enhance therapeutic outcomes and the quality of life of patients with spinal cord injury (SCI).

Exploring Ubiquitination in Spinal Cord Injury Therapy: Multifaceted Targets and Promising Strategies

Spinal cord injury (SCI) is a severely debilitating neurological condition that often results in significant functional impairment and is associated with poor long-term prognosis. Edema, oxidative stress, inflammatory responses, and cell death are the primary factors contributing to secondary injury following spinal cord damage. Ubiquitination is a crucial intracellular mechanism for protein regulation that has garnered significant attention as a therapeutic target in a variety of diseases. Numerous studies have shown that ubiquitination plays a key role in modulating processes such as inflammatory responses, apoptosis, and nerve regeneration following SCI, thereby influencing injury repair. Accordingly, targeting ubiquitination has the potential for mitigating harmful inflammatory responses, inhibiting dysregulated programmed cell death, and protecting the integrity of the blood-spinal cord barrier, thereby providing a novel therapeutic strategy for SCI. In this review, we discuss the role of ubiquitination and its potential as a therapeutic target in SCI, aiming to offer a foundation for developing ubiquitination-targeted therapies for this condition.

Advances in 3D printing combined with tissue engineering for nerve regeneration and repair

The repair of nerve damage has long posed a challenge owing to limited self-repair capacity and the highly differentiated nature of nerves. While new therapeutic and pharmacologic interventions have emerged in neurology, their regenerative efficacy remains limited. Tissue engineering offers a promising avenue for overcoming the limitations of conventional treatments and increasing the outcomes of regenerative repair. By implanting scaffolds into damaged nerve tissue sites, the repair and functional reconstruction of nerve injuries can be significantly facilitated. The integration of three-dimensional (3D) printing technology introduces a novel approach for accurate simulation and scalably fabricating neural tissue structures. Tissue-engineered scaffolds developed through 3D printing technology are expected to be a viable therapeutic option for nerve injuries, with broad applicability and continued development. This review systematically examines recent advances in 3D printing and tissue engineering for nerve regeneration and repair. It details the basic principles and construction strategies of neural tissue engineering and explores the crucial role of 3D printing technology. Additionally, it elucidates specific applications and technical challenges associated with this integrated approach, thereby providing valuable insights into innovative strategies and pragmatic implementation within this field.

MAPK signaling pathway in spinal cord injury: Mechanisms and therapeutic potential

Spinal cord injury (SCI) is a severe disabling injury of the central nervous system that can lead to motor, sensory, and autonomic dysfunction below the level of the injury. According to its pathophysiological process, SCI can be divided into primary injury and secondary injury. Currently, multiple therapeutic strategies have been proposed to alleviate secondary injury and overcome the occurrence of neurodegenerative events. Although current treatment modalities have achieved varying degrees of success, they cannot effectively intervene or treat its pathological processes, which may be due to the complex treatment and protection mechanisms involved. Research has confirmed that signaling pathways play a crucial role in the pathological processes of SCI and the mechanisms of neuronal recovery. Mitogen-activated protein kinase (MAPK) signaling pathway plays a crucial role in neuronal differentiation, growth, survival and axon regeneration after central nervous system injury. Meanwhile, the MAPK signaling pathway is an important pathway closely related to the pathological processes of SCI. The MAPK signaling pathway is abnormally activated after SCI, and inhibiting the activity of MAPK pathway can effectively inhibit inflammation, oxidative stress, pain and apoptosis to promote the recovery of nerve function after SCI. Based on the role of the MAPK pathway in SCI, it may be a potential therapeutic target. This article summarizes the role and mechanism of MAPK pathway in SCI, and discusses the shortcomings and shortcomings of MAPK pathway in SCI field, as well as the potential challenges of targeting MAPK pathway in SCI treatment strategies. This article aims to elucidate the mechanism of the MAPK pathway in SCI to emphasize the role of targeting the MAPK pathway in the treatment of SCI, providing a theoretical basis for the MAPK pathway as a potential therapeutic target for SCI treatment.

Shh Protects the Injured Spinal Cord in Mice by Promoting the Proliferation and Inhibiting the Apoptosis of Nerve Cells via the Gli1-TGF-β1/ERK Axis

Spinal cord injury (SCI) is a common neurological trauma that cannot be completely cured with surgical techniques and medications. In this study, we established a mouse SCI model and used an adeno-associated virus (AAV) to achieve the high expression of sonic hedgehog (Shh) at the injury site to further investigate the therapeutic effect and mechanism of Shh on SCI. The results of the present study show that Shh may promote motor function recovery. The present findings demonstrate the protective effect of Shh overexpression in SCI by regulating the proliferation and apoptosis of nerve cells at the site of SCI. Shh promotes the proliferation of early microglia, inhibits the proliferation of early astrocytes, and promotes the formation of neurons at the site of injury. In addition, Shh may inhibit apoptosis at the SCI site. The mechanism by which Shh regulates nerve cells at the site of SCI may involve glioma-associated oncogene 1 (Gli1). The present research indicates that Gli1 regulates the transforming growth factor-β (TGF-β) signaling pathway, inhibiting the classic TGF-β1/Smad signaling pathway and activating the TGF-β1/extracellular regulated protein kinase (ERK) signaling pathway. Collectively, these findings suggest that Shh is a regulatory molecule involved in nerve cell proliferation and apoptosis. High Shh expression can accelerate motor function recovery after SCI, indicating that it may be a promising therapeutic approach for SCI.

Targeting Remyelination in Spinal Cord Injury: Insights and Emerging Therapeutic Strategies

INTRODUCTION

Spinal cord injury (SCI) is a severe neurological disease characterized by significant motor, sensory, and autonomic dysfunctions. SCI is a major global disability cause, often resulting in long-term neurological impairments due to the impeded regeneration and remyelination of axons. A SCI interferes with communication between the brain and the spinal cord networks that control neurological functions. Recent advancements in understanding the molecular and cellular mechanisms of remyelination have opened novel therapeutic interventions.

METHOD

This review systematically sourced articles related to spinal chord injury, remyelination, regeneration and pathophysiology from major medical databases, including Scopus, PubMed, and Web of Science.

RESULTS

This review discusses the efficacy of targeted therapy in enhancing myelin repair after SCI by identifying key molecules and signaling pathways. This explores the effectiveness of specific pharmacological agents and biological factors in promoting oligodendrocyte precursor cell proliferation, differentiation, and myelin sheath formation using in vitro and in vivo models. Targeted therapies have shown promising results in improving remyelination, providing hope for functional recovery in SCI patients.

CONCLUSIONS

This review demonstrates challenges and future perspectives in translating findings into clinical practice, emphasizing safety profiles, delivery method optimization, and combinatory therapy potential. This review also supports the possibility of targeted remyelination therapies as a promising strategy for SCI treatment, paving the way for future clinical applications.

Conductive, injectable hydrogel equipped with tetramethylpyrazine regulates ferritinophagy and promotes spinal cord injury repair

Up to now, the clinical treatment of spinal cord injury (SCI) to recover the locomotion function, sensory function, and autonomic function of patients is a global medical challenge. In this study, based on the excellent effects of Tetramethylpyrazine (TMP) on regulating pathological micro-environment, we designed a new injectable conductive hydrogel consists of water-soluble polypyrrole (Ppy), agar, and TMP. The TMP@PA hydrogel has excellent physicochemical properties, bio-safety, and drug release ability, which can be injected into lesions in situ without secondary injury for SCI. Our in vivo and in vitro experiments have demonstrated that the TMP@PA hydrogel can not only fill the spinal cord cavity to reconstruct the electrical conduction pathway but also release TMP continuously to inhibit ferroptosis by regulating nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy regulated by Yes-Associated Protein (YAP) to promote SCI repair. Collectively, TMP@PA hydrogel may be an effective tissue engineering scaffold to treat SCI with highly promising clinical applications.

Regenerative medicine approaches for the treatment of spinal cord injuries: Progress and challenges

Spinal cord injury (SCI) is a profound medical condition that significantly hampers motor function, imposing substantial limitations on daily activities and exerting a considerable financial burden on patients and their families. The constrained regenerative capacity of endogenous spinal cord tissue, exacerbated by the inflammatory response following the initial trauma, poses a formidable obstacle to effective therapy. Recent advancements in the field, stem cells, biomaterials, and molecular therapy, show promising outcomes. This review provides a comprehensive analysis of tissue engineering and regenerative medicine approaches for SCI treatment, including cell transplantation, tissue-engineered construct implantation, and other potential therapeutic strategies. Additionally, it sheds light on preclinical animal studies and recent clinical trials incorporating these modalities, providing a glimpse into the evolving landscape of SCI management. STATEMENT OF SIGNIFICANCE: The investigation into spinal cord injury (SCI) treatments focuses on reducing long-term impacts by targeting scar inhibition and enhancing regeneration through stem cells, with or without growth factors. Induced pluripotent stem cells (iPSCs) show promise for autologous use, with clinical trials confirming their safety. Challenges include low cell viability and difficulty in targeted differentiation. Biomaterial scaffolds hold potential for improving cell viability and integration, and extracellular vesicles (EVs) are emerging as a novel therapy. While EV research is in its early stages, stem cell trials demonstrate safety and potential recovery. Advancing tissue engineering approaches with biomaterial scaffolds is crucial for human trials.

Advancements and mechanisms of stem cell-based therapies for spinal cord injury in animals

Spinal cord injury (SCI) is a neurodegenerative disorder of the central nervous system that can lead to permanent loss of sensation and voluntary movement beyond the affected area. Extensive preclinical and clinical trials have been conducted to evaluate the safety and effectiveness of stem cells for the treatment of various central nervous system diseases or disorders, including SCI. However, several challenges hinder nerve cell regeneration in the injured spinal cord, such as extensive cell loss, limited neural cell regeneration capacity, axonal disruption, and the presence of growth-inhibiting molecules, particularly astroglial scarring or glial scars at the injury site in chronic cases. These obstacles pose significant challenges for physicians in restoring normal motor and sensory nerve function in both humans and animals following SCI. This review focuses on SCI pathogenesis, the mechanisms underlying the therapeutic potential of mesenchymal stem cells in SCI, and the potential of stem cell-based therapies as promising avenues for treatment. This review article also included relevant preclinical and clinical data from animal studies.

Epigenetic modifications of inflammation in spinal cord injury

Spinal cord injury (SCI) is a central nervous system injury that leads to neurological dysfunction or paralysis, which seriously affects patients' quality of life and causes a heavy social and economic burden. The pathological mechanism of SCI has not been fully revealed, resulting in unsatisfactory clinical treatment. Therefore, more research is urgently needed to reveal its precise pathological mechanism. Numerous studies have shown that inflammation is closely related to various pathological processes in SCI. Inflammatory response is an important pathological process leading to secondary injury, and sustained inflammatory response can exacerbate the injury and hinder the recovery of neurological function after injury. Epigenetic modification is considered to be an important regulatory mechanism in the pathological process of many diseases. Epigenetic modification mainly affects the function and characteristics of genes through the reversibility of mechanisms such as DNA methylation, histone modification, and regulation of non-coding RNA, thus having a significant impact on the pathological process of diseases and the survival state of the body. Recently, the role of epigenetic modification in the inflammatory response of SCI has gradually entered the field of view of researchers, and epigenetic modification may be a potential means to treat SCI. In this paper, we review the effects and mechanisms of different types of epigenetic modifications (including histone modifications, DNA methylation, and non-coding RNAs) on post-SCI inflammation and their potential therapeutic effects on inflammation to improve our understanding of the secondary SCI stage. This review aims to help identify new markers, signaling pathways and targeted drugs, and provide theoretical basis and new strategies for the diagnosis and treatment of SCI.

A novel reconstruction model for thoracic spinal cord injury in swine

Spinal cord (SC) reconstruction (process to reestablish the severed neural continuity at the injury site) may provide better recovery from blunt SC injury (SCI). A miniature swine model of blunt SC compression was used to test the hypothesis that reconstruction of the SC with sural nerve in combination with surgical decompression and stabilization improves functional, macro- and microstructural recovery compared to decompression and stabilization alone. Following blunt T9-T11 SC compression injury, five adult Yucatan gilts randomly received laminectomy and polyethylene glycol (as fusogen) with (n = 3) or without (n = 2) sural nerve graft SC reconstruction. Fusogens are a heterogeneous collection of chemicals that fuse the axon membrane and are currently used to augment epineural coaptation during peripheral nerve graft reconstruction. Outcome measures of recovery included weekly sensory and motor assessments, various measurements obtained from computed tomography (CT) myelograms up to 12 weeks after injury Measurements from postmortem magnetic resonance imaging (MRI) and results from spinal cord histology performed 12 weeks after injury were also reported. Vertebral canal (VC), SC and dural sac (DS) dimensions and areas were quantified on 2-D CT images adjacent to the injury. Effort to stand and response to physical manipulation improved 7 and 9 weeks and 9 and 10 weeks, respectively, after injury in the reconstruction group. Myelogram measures indicated greater T13-T14 VC, smaller SC, and smaller DS dimensions in the reconstruction cohort, and increased DS area increased DS/VC area ratio, and higher contrast migration over time. Spinal cord continuity was evident in 2 gilts in the reconstruction cohort with CT and MRI imaging. At the SCI, microstructural alterations included axonal loss and glial scarring. Better functional outcomes were observed in subjects treated with sural nerve SC reconstruction. Study results support the use of this adult swine model of blunt SCI. Long-term studies with different nerve grafts or fusogens are required to expand upon these findings.

A review of recent advances of piezoelectric poly-L-lactic acid for biomedical applications

Poly-L-lactic acid (PLLA), recognized as a piezoelectric material, not only demonstrates exceptional piezoelectric properties but also exhibits commendable biocompatibility and biodegradability. These properties render PLLA highly promising for diverse applications, including sensors, wearable devices, biomedical engineering, and related domains. This review offers a comprehensive overview of the distinctive piezoelectric effect of PLLA-based material and delves into the latest advancements in its preparation strategies as a piezoelectric material. It further presents recent research progress in PLLA-based piezoelectric materials, particularly in the realms of health monitoring, skin repair, nerve regeneration, and tissue repair. The discourse extends to providing insights into potential future trajectories for the development of PLLA-based piezoelectric materials.

Contribution of ApoB-100/SORT1-Mediated Immune Microenvironment in Regulating Oxidative Stress, Inflammation, and Ferroptosis After Spinal Cord Injury

This study aims to explore the impacts of ApoB-100/SORT1-mediated immune microenvironment during acute spinal cord injury (SCI), and to investigate the potential mechanism. CB57BL/6 mice underwent moderate thoracic contusion injury to establish the SCI animal model, and received ApoB-100 lentivirus injection to interfere ApoB-100 level. Functional recovery was assessed using the Basso, Beattie, and Bresnahan (BBB) score and footprint analysis. Transmission electron microscopy was applied to observe the ultrastructure of the injured spinal cord tissue. Hematoxylin-eosin (HE) staining and Perls staining were conducted to assess histological changes and iron deposition. Biochemical factor and cytokines were detected using their commercial kits. M1/M2 macrophage markers were detected by immunofluorescence assay in vivo and by flow cytometry in vitro. HT22 neurons were simulated by lipopolysaccharide (LPS), followed by incubation with polarized macrophage medium to simulate the immune microenvironment of injured spinal cord in vitro. The local immune microenvironment is changed in SCI mice, accompanied with the occurrence of oxidative stress and the elevation of both M1 and M2 macrophages. Knockdown of ApoB-100 ameliorates oxidative stress and lipid disorder, and inhibits inflammation and ferroptosis in SCI mice. Importantly, knockdown of ApoB-100 can partly restrict M1 macrophages but does not change M2 macrophage proportion in SCI mice. Further, M1 macrophages are observed to attenuate the inflammatory response, oxidative stress, and ferroptosis levels of LPS-induced HT22 cells, which is further strengthened by SORT1 knockdown. Blockage of ApoB-100/SORT1-mediated immune microenvironment plays a protective role against SCI via inhibiting oxidative stress, inflammation, lipid disorders, and ferroptosis, providing novel insights of the targeted therapy of SCI.

Evaluation puramatrix as a 3D microenvironment for neural differentiation of human breastmilk stem cells

The extracellular matrix is recognized as an efficient and determining component in the growth, proliferation, and differentiation of cells due to its ability to perceive and respond to environmental signals. Applying three-dimensional scaffolds can create conditions similar to the extracellular matrix and provide an opportunity to investigate cell fate. In this study, we employed the PuraMatrix hydrogel scaffold as an advanced cell culture platform for the neural differentiation of stem cells derived from human breastmilk to design an opportune model for tissue engineering. Isolated stem cells from breastmilk were cultured and differentiated into neural-like cells on PuraMatrix peptide hydrogel and in the two-dimensional system. The compatibility of breastmilk-derived stem cells with PuraMatrix and cell viability was evaluated by scanning electron microscopy and MTT assay, respectively. Induction of differentiation was achieved by exposing cells to the neurogenic medium. After 21 days of the initial differentiation process, the expression levels of glial fibrillary acidic protein (GFAP), microtubule-associated protein (MAP2), β-tubulin III, and neuronal nuclear antigen (NeuN) were analyzed using the immunostaining technique. The results illustrated a notable expression of MAP2, β-tubulin-III, and NeuN in the three-dimensional cell culture in comparison to the two-dimensional system, indicating the beneficial effect of PuraMatrix scaffolds in the process of differentiating breastmilk-derived stem cells into neural-like cells. In view of the obtained results, the combination of breastmilk-derived stem cells and PuraMatrix hydrogel scaffold could be an advisable preference for neural tissue regeneration and cell therapy.

Biomimetic Dual-Network Collagen Fibers with Porous and Mechanical Cues Reconstruct Neural Stem Cell Niche via AKT/YAP Mechanotransduction after Spinal Cord Injury

Tissue engineering scaffolds can mediate the maneuverability of neural stem cell (NSC) niche to influence NSC behavior, such as cell self-renewal, proliferation, and differentiation direction, showing the promising application in spinal cord injury (SCI) repair. Here, dual-network porous collagen fibers (PCFS) are developed as neurogenesis scaffolds by employing biomimetic plasma ammonia oxidase catalysis and conventional amidation cross-linking. Following optimizing the mechanical parameters of PCFS, the well-matched Young's modulus and physiological dynamic adaptability of PCFS (4.0 wt%) have been identified as a neurogenetic exciter after SCI. Remarkably, porous topographies and curving wall-like protrusions are generated on the surface of PCFS by simple and non-toxic CO2 bubble-water replacement. As expected, PCFS with porous and matched mechanical properties can considerably activate the cadherin receptor of NSCs and induce a series of serine-threonine kinase/yes-associated protein mechanotransduction signal pathways, encouraging cellular orientation, neuron differentiation, and adhesion. In SCI rats, implanted PCFS with matched mechanical properties further integrated into the injured spinal cords, inhibited the inflammatory progression and decreased glial and fibrous scar formation. Wall-like protrusions of PCFS drive multiple neuron subtypes formation and even functional neural circuits, suggesting a viable therapeutic strategy for nerve regeneration and functional recovery after SCI.

The roles of neural stem cells in myelin regeneration and repair therapy after spinal cord injury

Spinal cord injury (SCI) is a complex tissue injury that results in a wide range of physical deficits, including permanent or progressive disabilities of sensory, motor and autonomic functions. To date, limitations in current clinical treatment options can leave SCI patients with lifelong disabilities. There is an urgent need to develop new therapies for reconstructing the damaged spinal cord neuron-glia network and restoring connectivity with the supraspinal pathways. Neural stem cells (NSCs) possess the ability to self-renew and differentiate into neurons and neuroglia, including oligodendrocytes, which are cells responsible for the formation and maintenance of the myelin sheath and the regeneration of demyelinated axons. For these properties, NSCs are considered to be a promising cell source for rebuilding damaged neural circuits and promoting myelin regeneration. Over the past decade, transplantation of NSCs has been extensively tested in a variety of preclinical models of SCI. This review aims to highlight the pathophysiology of SCI and promote the understanding of the role of NSCs in SCI repair therapy and the current advances in pathological mechanism, pre-clinical studies, as well as clinical trials of SCI via NSC transplantation therapeutic strategy. Understanding and mastering these frontier updates will pave the way for establishing novel therapeutic strategies to improve the quality of recovery from SCI.

Recent advances on signaling pathways and their inhibitors in spinal cord injury

Spinal cord injury (SCI) is a serious and disabling central nervous system injury. Its complex pathological mechanism can lead to sensory and motor dysfunction. It has been reported that signaling pathway plays a key role in the pathological process and neuronal recovery mechanism of SCI. Such as PI3K/Akt, MAPK, NF-κB, and Wnt/β-catenin signaling pathways. According to reports, various stimuli and cytokines activate these signaling pathways related to SCI pathology, thereby participating in the regulation of pathological processes such as inflammation response, cell apoptosis, oxidative stress, and glial scar formation after injury. Activation or inhibition of relevant pathways can delay inflammatory response, reduce neuronal apoptosis, prevent glial scar formation, improve the microenvironment after SCI, and promote neural function recovery. Based on the role of signaling pathways in SCI, they may be potential targets for the treatment of SCI. Therefore, understanding the signaling pathway and its inhibitors may be beneficial to the development of SCI therapeutic targets and new drugs. This paper mainly summarizes the pathophysiological process of SCI, the signaling pathways involved in SCI pathogenesis, and the potential role of specific inhibitors/activators in its treatment. In addition, this review also discusses the deficiencies and defects of signaling pathways in SCI research. It is hoped that this study can provide reference for future research on signaling pathways in the pathogenesis of SCI and provide theoretical basis for SCI biotherapy.

Targeted Therapy of Spinal Cord Injury: Inhibition of Apoptosis Is a Promising Therapeutic Strategy

Spinal cord injury (SCI) is a serious disabling central nervous system injury that can lead to motor, sensory, and autonomic dysfunction below the injury level. SCI can be divided into primary injury and secondary injury according to pathological process. Primary injury is mostly irreversible, while secondary injury is a dynamic regulatory process. Apoptosis is an important pathological event of secondary injury and has a significant effect on the recovery of nerve function after SCI. Nerve cell death can further aggravate the microenvironment of the injured site, leading to neurological dysfunction and thus affect the clinical outcome of patients. Therefore, apoptosis plays a crucial role in the pathological progression of secondary SCI, while inhibiting apoptosis may be a promising therapeutic strategy for SCI. This review will summarize and explore the factors that lead to cell death after SCI, the influence of cross talk between signaling pathways and pathways involved in apoptosis and discuss the influence of apoptosis on SCI, and the therapeutic significance of targeting apoptosis on SCI. This review helps us to understand the role of apoptosis in secondary SCI and provides a theoretical basis for the treatment of SCI based on apoptosis.

Hydrogen Sulfide can Scavenge Free Radicals to Improve Spinal Cord Injury by Inhibiting the p38MAPK/mTOR/NF-κB Signaling Pathway

Spinal cord injury (SCI) causes irreversible cell loss and neurological dysfunctions. Presently, there is no an effective clinical treatment for SCI. It can be the only intervention measure by relieving the symptoms of patients such as pain and fever. Free radical-induced damage is one of the validated mechanisms in the complex secondary injury following primary SCI. Hydrogen sulfide (H2S) as an antioxidant can effectively scavenge free radicals, protect neurons, and improve SCI by inhibiting the p38MAPK/mTOR/NF-κB signaling pathway. In this report, we analyze the pathological mechanism of SCI, the role of free radical-mediated the p38MAPK/mTOR/NF-κB signaling pathway in SCI, and the role of H2S in scavenging free radicals and improving SCI.

Changing trends in traumatic spinal cord injury in an aging society: Epidemiology of 1152 cases over 15 years from a single center in Japan

Traumatic spinal cord injury (TSCI) causes an insult to the central nervous system, often resulting in devastating temporary or permanent neurological impairment and disability, which places a substantial financial burden on the health-care system. This study aimed to clarify the up-to-date epidemiology and demographics of patients with TSCI treated at the largest SCI center in Japan. Data on all patients admitted to the Spinal Injuries Center with TSCI between May 2005 and December 2021 were prospectively collected using a customized, locally designed SCI database named the Japan Single Center Study for Spinal Cord Injury Database (JSSCI-DB). A total of 1152 patients were identified from the database. The study period was divided into the four- or five-year periods of 2005-2009, 2010-2013, 2014-2017, and 2018-2021 to facilitate the observation of general trends over time. Our results revealed a statistically significant increasing trend in age at injury. Since 2014, the average age of injury has increased to exceed 60 years. The most frequent spinal level affected by the injury was high cervical (C1-C4: 45.8%), followed by low cervical (C5-C8: 26.4%). Incomplete tetraplegia was the most common cause or etiology category of TSCI, accounting for 48.4% of cases. As the number of injuries among the elderly has increased, the injury mechanisms have shifted from high-fall trauma and traffic accidents to falls on level surfaces and downstairs. Incomplete tetraplegia in the elderly due to upper cervical TSCI has also increased over time. The percentage of injured patients with an etiology linked to alcohol use ranged from 13.2% (2005-2008) to 19% (2014-2017). Given that Japan has one of the highest aging populations in the world, epidemiological studies in this country will be very helpful in determining health insurance and medical costs and deciding strategies for the prevention and treatment of TSCI in future aging populations worldwide.

Injectable Hydrogel Loaded with CDs and FTY720 Combined with Neural Stem Cells for the Treatment of Spinal Cord Injury

Purpose

Spinal cord injury (SCI) is an incurable and disabling event that is accompanied by complex inflammation-related pathological processes, such as the production of excessive reactive oxygen species (ROS) by infiltrating inflammatory immune cells and their release into the extracellular microenvironment, resulting in extensive apoptosis of endogenous neural stem cells. In this study, we noticed the neuroregeneration-promoting effect as well as the ability of the innovative treatment method of FTY720-CDs@GelMA paired with NSCs to increase motor function recovery in a rat spinal cord injury model.

Methods

Carbon dots (CDs) and fingolimod (FTY720) were added to a hydrogel created by chemical cross-linking GelMA (FTY720-CDs@GelMA). The basic properties of FTY720-CDs@GelMA hydrogels were investigated using TEM, SEM, XPS, and FTIR. The swelling and degradation rates of FTY720-CDs@GelMA hydrogels were measured, and each group's ability to scavenge reactive oxygen species was investigated. The in vitro biocompatibility of FTY720-CDs@GelMA hydrogels was assessed using neural stem cells. The regeneration of the spinal cord and recovery of motor function in rats were studied following co-treatment of spinal cord injury using FTY720-CDs@GelMA hydrogel in combination with NSCs, utilising rats with spinal cord injuries as a model. Histological and immunofluorescence labelling were used to determine the regeneration of axons and neurons. The recovery of motor function in rats was assessed using the BBB score.

Results

The hydrogel boosted neurogenesis and axonal regeneration by eliminating excess ROS and restoring the regenerative environment. The hydrogel efficiently contained brain stem cells and demonstrated strong neuroprotective effects in vivo by lowering endogenous ROS generation and mitigating ROS-mediated oxidative stress. In a follow-up investigation, we discovered that FTY720-CDs@GelMA hydrogel could dramatically boost NSC proliferation while also promoting neuronal regeneration and synaptic formation, hence lowering cavity area.

Conclusion

Our findings suggest that the innovative treatment of FTY720-CDs@GelMA paired with NSCs can effectively improve functional recovery in SCI patients, making it a promising therapeutic alternative for SCI.

Neural stem cell therapies for spinal cord injury repair: an update on recent preclinical and clinical advances

Traumatic spinal cord injury (SCI) is a leading cause of lifelong disabilities. Permanent sensory, motor and autonomic impairments after SCI are substantially attributed to degeneration of spinal cord neurons and axons, and disintegration of neural network. To date, minimal regenerative treatments are available for SCI with an unmet need for new therapies to reconstruct the damaged spinal cord neuron-glia network and restore connectivity with the supraspinal pathways. Multipotent neural precursor cells (NPCs) have a unique capacity to generate neurons, oligodendrocytes and astrocytes. Due to this capacity, NPCs have been an attractive cell source for cellular therapies for SCI. Transplantation of NPCs has been extensively tested in preclinical models of SCI in the past two decades. These studies have identified opportunities and challenges associated with NPC therapies. While NPCs have the potential to promote neuroregeneration through various mechanisms, their low long-term survival and integration within the host injured spinal cord limit the functional benefits of NPC-based therapies for SCI. To address this challenge, combinatorial strategies have been developed to optimize the outcomes of NPC therapies by enriching SCI microenvironment through biomaterials, genetic and pharmacological therapies. In this review, we will provide an in-depth discussion on recent advances in preclinical NPC-based therapies for SCI. We will discuss modes of actions and mechanism by which engrafted NPCs contribute to the repair process and functional recovery. We will also provide an update on current clinical trials and new technologies that have facilitated preparation of medical-grade human NPCs suitable for transplantation in clinical studies.

Dual-directional regulation of spinal cord injury and the gut microbiota

There is increasing evidence that the gut microbiota affects the incidence and progression of central nervous system diseases via the brain-gut axis. The spinal cord is a vital important part of the central nervous system; however, the underlying association between spinal cord injury and gut interactions remains unknown. Recent studies suggest that patients with spinal cord injury frequently experience intestinal dysfunction and gut dysbiosis. Alterations in the gut microbiota can cause disruption in the intestinal barrier and trigger neurogenic inflammatory responses which may impede recovery after spinal cord injury. This review summarizes existing clinical and basic research on the relationship between the gut microbiota and spinal cord injury. Our research identified three key points. First, the gut microbiota in patients with spinal cord injury presents a key characteristic and gut dysbiosis may profoundly influence multiple organs and systems in patients with spinal cord injury. Second, following spinal cord injury, weakened intestinal peristalsis, prolonged intestinal transport time, and immune dysfunction of the intestine caused by abnormal autonomic nerve function, as well as frequent antibiotic treatment, may induce gut dysbiosis. Third, the gut microbiota and associated metabolites may act on central neurons and affect recovery after spinal cord injury; cytokines and the Toll-like receptor ligand pathways have been identified as crucial mechanisms in the communication between the gut microbiota and central nervous system. Fecal microbiota transplantation, probiotics, dietary interventions, and other therapies have been shown to serve a neuroprotective role in spinal cord injury by modulating the gut microbiota. Therapies targeting the gut microbiota or associated metabolites are a promising approach to promote functional recovery and improve the complications of spinal cord injury.

The GLP-1 receptor agonist exenatide improves recovery from spinal cord injury by inducing macrophage polarization toward the M2 phenotype

Although a wide variety of mechanisms take part in the secondary injury phase of spinal cord injury (SCI), inflammation is the most important factor implicated in the sequelae after SCI. Being central to the inflammation reaction, macrophages and their polarization are a topic that has garnered wide interest in the studies of SCI secondary injury. The glucagon-like peptide 1 (GLP-1) receptor agonist exenatide has been shown to enhance the endoplasmic reticulum stress response and improve motor function recovery after spinal cord injury (SCI). Since exenatide has also been reported to induce the production of M2 cells in models of cerebral infarction and neurodegenerative diseases, this study was conducted to examine the effects of exenatide administration on the inflammation process that ensues after spinal cord injury. In a rat contusion model of spinal cord injury, the exenatide group received a subcutaneous injection of 10 μg exenatide immediately after injury while those in the control group received 1 mL of phosphate-buffered saline. Quantitative RT-PCR and immunohistochemical staining were used to evaluate the effects of exenatide administration on the macrophages infiltrating the injured spinal cord, especially with regard to macrophage M1 and M2 profiles. The changes in hind limb motor function were assessed based on Basso, Beattie, Bresnahan locomotor rating scale (BBB scale) scores. The improvement in BBB scale scores was significantly higher in the exenatide group from day 7 after injury and onwards. Quantitative RT-PCR revealed an increase in the expression of M2 markers and anti-inflammatory interleukins in the exenatide group that was accompanied by a decrease in the expression of M1 markers and inflammatory cytokines. Immunohistochemical staining showed no significant difference in M1 macrophage numbers between the two groups, but a significantly higher number of M2 macrophages was observed in the exenatide group on day 3 after injury. Our findings suggest that exenatide administration promoted the number of M2-phenotype macrophages after SCI, which may have led to the observed improvement in hind limb motor function in a rat model of SCI.

Ligand-Screened Cerium-Based MOF Microcapsules Promote Nerve Regeneration via Mitochondrial Energy Supply

Although mitochondria are crucial for recovery after spinal cord injury (SCI), therapeutic strategies to modulate mitochondrial metabolic energy to coordinate the immune response and nerve regeneration are lacking. Here, a ligand-screened cerium-based metal-organic framework (MOF) with better ROS scavenging and drug-loading abilities is encapsulated with polydopamine after loading creatine to obtain microcapsules (Cr/Ce@PDA nanoparticles), which reverse the energy deficits in both macrophages and neuronal cells by combining ROS scavenging and energy supplementation. It reprogrames inflammatory macrophages to the proregenerative phenotype via the succinate/HIF-1α/IL-1β signaling axis. It also promotes the regeneration and differentiation of neural cells by activating the mTOR pathway and paracrine function of macrophages. In vivo experiments further confirm the effect of the microcapsules in regulating early ROS-inflammation positive-feedback chain reactions and continuously promoting nerve regeneration. This study provides a new strategy for correcting mitochondrial energy deficiency in the immune response and nerve regeneration following SCI.

Engineered Multifunctional Zinc-Organic Framework-Based Aggregation-Induced Emission Nanozyme for Accelerating Spinal Cord Injury Recovery

Functional recovery following a spinal cord injury (SCI) is challenging. Traditional drug therapies focus on the suppression of immune responses; however, strategies for alleviating oxidative stress are lacking. Herein, we developed the zinc-organic framework (Zn@MOF)-based aggregation-induced emission-active nanozymes for accelerating recovery following SCI. A multifunctional Zn@MOF was modified with the aggregation-induced emission-active molecule 2-(4-azidobutyl)-6-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)-1H-phenalene-1,3-dione via a bioorthogonal reaction, and the resulting nanozymes were denoted as Zn@MOF-TPD. These nanozymes gradually released gallic acid and zinc ions (Zn2+) at the SCI site. The released gallic acid, a scavenger of reactive oxygen species (ROS), promoted antioxidation and alleviated inflammation, re-establishing the balance between ROS production and the antioxidant defense system. The released Zn2+ ions inhibited the activity of matrix metalloproteinase 9 (MMP-9) to facilitate the regeneration of neurons via the ROS-mediated NF-κB pathway following secondary SCI. In addition, Zn@MOF-TPD protected neurons and myelin sheaths against trauma, inhibited glial scar formation, and promoted the proliferation and differentiation of neural stem cells, thereby facilitating the repair of neurons and injured spinal cord tissue and promoting functional recovery in rats with contusive SCI. Altogether, this study suggests that Zn@MOF-TPD nanozymes possess a potential for alleviating oxidative stress-mediated pathophysiological damage and promoting motor recovery following SCI.

Neuromodulation to guide circuit reorganization with regenerative therapies in upper extremity rehabilitation following cervical spinal cord injury

Spinal cord injury (SCI) is a profoundly debilitating condition with no effective treatment to date. The complex response of the central nervous system (CNS) to injury and its limited regeneration capacity pose bold challenges for restoring function. Cervical SCIs are the most prevalent and regaining hand function is a top priority for individuals living with cervical SCI. A promising avenue for addressing this challenge arises from the emerging field of regenerative rehabilitation, which combines regenerative biology with physical medicine approaches. The hypothesis for optimizing gains in upper extremity function centers on the integration of targeted neurorehabilitation with novel cell- and stem cell-based therapies. However, the precise roles and synergistic effects of these components remain poorly understood, given the intricate nature of SCI and the diversity of regenerative approaches. This perspective article sheds light on the current state of regenerative rehabilitation for cervical SCI. Notably, preclinical research has yet to fully incorporate rehabilitation protocols that mimic current clinical practices, which often rely on neuromodulation strategies to activate spared circuits below the injury level. Therefore, it becomes imperative to comprehensively investigate the combined effects of neuromodulation and regenerative medicine strategies in animal models before translating these therapies to individuals with SCI. In cases of severe upper extremity paralysis, the advent of neuromodulation strategies, such as corticospinal tract (CST) and spinal cord stimulation, holds promise as the next frontier in enhancing the effectiveness of cell- and stem cell-based therapies. Future preclinical studies should explore this convergence of neuromodulation and regenerative approaches to unlock new possibilities for upper extremity treatment after SCI.

Spinal cord injury: Olfactory ensheathing cell-based therapeutic strategies

Spinal cord injury (SCI) is a highly disabling neurological disorder that is difficult to treat due to its complex pathophysiology and nerve regeneration difficulties. Hence, effective SCI treatments are necessary. Olfactory ensheathing cells (OECs), glial cells derived from the olfactory bulb or mucosa, are ideal candidates for SCI treatment because of their neuroprotective and regenerative properties, ample supply, and convenience. In vitro, animal model, and human trial studies have reported discoveries on OEC transplantation; however, shortcomings have also been demonstrated. Recent studies have optimized various OEC transplantation strategies, including drug integration, biomaterials, and gene editing. This review aims to introduce OECs mechanisms in repairing SCI, summarize the research progress of OEC transplantation-optimized strategies, and provide novel research ideas for SCI treatment.

Disease-specific interventions using cell therapies for spinal cord disease/injury

Traumatic spinal cord injury (SCI) may occur across the lifespan and is of global relevance. Damage of the spinal cord results in para- or tetraplegia and is associated with neuropathic pain, spasticity, respiratory, and autonomic dysfunction (i.e., control of bladder-bowel function). While the acute surgical treatment aims at stabilizing the spine and decompressing the damaged spinal cord, SCI patients require neurorehabilitation to restore neural function and to compensate for any impairments including motor disability, pain treatment, and bladder/bowel management. However, the spinal cord has a limited capacity to regenerate and much of the disability may persist, depending on the initial lesion severity and level of injury. For this reason, and the lack of effective drug treatments, there is an emerging interest and urgent need in promoting axonal regeneration and remyelination after SCI through cell- and stem-cell based therapies. This review briefly summarizes the state-of the art management of acute SCI and its neurorehabilitation to critically appraise phase I/II trials from the last two decades that have investigated cell-based therapies (i.e., Schwann cells, macrophages, and olfactory ensheathing cells) and stem cell-based therapies (i.e., neural stem cells, mesenchymal, and hematopoietic stem cells). Recently, two large multicenter trials provided evidence for the safety and feasibility of neural stem cell transplantation into the injured cord, whilst two monocenter trials also showed this to be the case for the transplantation of Schwann cells into the posttraumatic cord cavity. These are milestone studies that will facilitate further interventional trials. However, the clinical adoption of such approaches remains unproven, as there is only limited encouraging data, often in single patients, and no proven trial evidence to support regulatory approval.

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.

Building a pathway to recovery: Targeting ECM remodeling in CNS injuries

Extracellular matrix (ECM) is a complex and dynamic network of proteoglycans, proteins, and other macromolecules that surrounds cells in tissues. The ECM provides structural support to cells and plays a critical role in regulating various cellular functions. ECM remodeling is a dynamic process involving the breakdown and reconstruction of the ECM. This process occurs naturally during tissue growth, wound healing, and tissue repair. However, in the context of central nervous system (CNS) injuries, dysregulated ECM remodeling can lead to the formation of fibrotic and glial scars. CNS injuries encompass various traumatic events, including concussions and fractures. Following CNS trauma, the formation of glial and fibrotic scars becomes prominent. Glial scars primarily consist of reactive astrocytes, while fibrotic scars are characterized by an abundance of ECM proteins. ECM remodeling plays a pivotal and tightly regulated role in the development of these scars after spinal cord and brain injuries. Various factors like ECM components, ECM remodeling enzymes, cell surface receptors of ECM molecules, and downstream pathways of ECM molecules are responsible for the remodeling of the ECM. The aim of this review article is to explore the changes in ECM during normal physiological conditions and following CNS injuries. Additionally, we discuss various approaches that target various factors responsible for ECM remodeling, with a focus on promoting axon regeneration and functional recovery after CNS injuries. By targeting ECM remodeling, it may be possible to enhance axonal regeneration and facilitate functional recovery after CNS injuries.

Syntaphilin Inactivation Can Enhance Axonal Mitochondrial Transport to Improve Spinal Cord Injury

Mitochondria are important organelle of eukaryotic cells. They consists of a large number of different proteins that provide most of the ATP and supply power for the growth, function, and regeneration of neurons. Therefore, smitochondrial transport ensures that adequate ATP is supplied for metabolic activities. Spinal cord injury (SCI), a detrimental condition, has high morbidity and mortality rates. Currently, the available treatments only provide symptomatic relief for long-term disabilities. Studies have implicated mitochondrial transport as a critical factor in axonal regeneration. Hence, enhancing mitochondrial transports could be beneficial for ameliorating SCI. Syntaphilin (Snph) is a mitochondrial docking protein that acts as a "static anchor," and its inhibition enhances mitochondrial transports. Therefore, Snph as a key mediator of mitochondrial transports, may contribute to improving axonal regeneration following SCI. Herein, we examine Snph's biological effects and its relation to mitochondrial pathway. Then, we elaborate on mitochondrial transports after SCI, the possible role of Snph in SCI, and some possible therapeutic approaches by Snph.

Nanomedicine innovations in spinal cord injury management: Bridging the gap

Spinal cord injury (SCI) has devastating effects on a person's physical, social, and professional well-being. It is a life-altering neurological condition that significantly impacts individuals and their caregivers on a socioeconomic level. Recent advancements in medical therapy have greatly improved the diagnosis, stability, survival rates, and overall well-being of SCI patients. However, there are still limited options available for enhancing neurological outcomes in these patients. The complex pathophysiology of SCI, along with the numerous biochemical and physiological changes that occur in the damaged spinal cord, contribute to this gradual improvement. Currently, there are no therapies that offer the possibility of recovery for SCI, although several therapeutic approaches are being developed. However, these therapies are still in the early stages and have not yet demonstrated effectiveness in repairing the damaged fibers, which hinders cellular regeneration and the full restoration of motor and sensory functions. Considering the importance of nanotechnology and tissue engineering in treating neural tissue injuries, this review focuses on the latest advancements in nanotechnology for SCI therapy and tissue healing. It examines research articles from the PubMed database that specifically address SCI in the field of tissue engineering, with an emphasis on nanotechnology as a therapeutic approach. The review evaluates the biomaterials used for treating this condition and the techniques employed to create nanostructured biomaterials.

Nissl Granules, Axonal Regeneration, and Regenerative Therapeutics: A Comprehensive Review

Nissl granules, traditionally recognized for their pivotal role in protein synthesis within neuronal cell bodies, are emerging as intriguing components with far-reaching implications in the realm of regenerative therapeutics. This abstract encapsulates the essence of a comprehensive review, exploring the nexus between Nissl granules, axonal regeneration, and their transformative applications in regenerative medicine. The molecular intricacies of Nissl granules form the foundation of this exploration, unraveling their dynamic role in orchestrating cellular responses, particularly in the context of axonal regeneration. As we delve into the interplay between Nissl granules and regenerative processes, this review highlights the diverse mechanisms through which these granules contribute to neuronal repair and recovery. Beyond their conventional association with neurobiology, recent advancements underscore the translational potential of Nissl granules as therapeutic agents. Insights into their involvement in enhancing axonal regeneration prompt a reconsideration of these granules as key players in the broader field of regenerative medicine. The abstract encapsulates evidence suggesting that modulating Nissl granule-related pathways holds promise for augmenting tissue regeneration, extending their applicability beyond the confines of the nervous system. This review aims to serve as a valuable resource for medical professionals, researchers, and clinicians seeking to comprehend the multifaceted role of Nissl granules in regenerative therapeutics. By illuminating the intricate connections between Nissl granules, axonal regeneration, and therapeutic applications, this work aspires to catalyze further research and innovation, ultimately contributing to the evolution of regenerative strategies that harness the innate reparative capacities within cellular constituents.

Fabrication of elliptically constructed liquid crystalline elastomeric scaffolds for 3D artificial tissues

Inspired by the orientation and the fibrous structure of human muscle tissues, we fabricated preconstructed porous liquid crystalline (LC) scaffolds through a two-step polymerization and salt leaching method. A novel strategy combining the aligning properties of LCs and the ease of processing of elastomers for the preparation of elliptical scaffolds for muscle cell culture was proposed in this research. Different from the other types of scaffolds, our biocompatible LC scaffold that can be implanted into the human body using a supporting unit to improve the mechanical properties compared with those of natural muscle. To evaluate the synthesized scaffolds, in vitro experiments using normal human dermal fibroblast (NHDF) cells and smooth muscle cells from rats were carried out, and the sample cells were cultured on each sample scaffold. Based on the results of long-term culture of NHDF cells on the LC scaffolds, it can be confirmed that all three kinds of LC scaffolds have good biocompatibility and provide enough space for cell growth. The addition of gelatin can significantly enhance the biocompatibility of the synthesized scaffolds. Evaluation of scaffold morphologies on cell growth indicates that the molecular arrangement on the scaffolds can induce the growth direction of smooth muscle cells to a certain extent, thereby increasing the formation of highly ordered arrangement tissues. The population doubling time of NHDF cells on the different scaffolds suggest that gelatin can improve the attachment and growth of cells. Investigation of cell viability on LC scaffolds shows that the original LC scaffolds already possess excellent biocompatibility. Additionally, the average cell viability of smooth muscle cells was above 90%, showing that the LC scaffolds in this research are suitable for application in muscle tissue engineering. Based on the results, the gelatin-coated scaffolds are more conducive to the growth of cells in this research and provide promising candidates for tissue engineering in biomedical fields and research fields.

Encapsulation of Human Spinal Cord Progenitor Cells in Hyaluronan-Gelatin Hydrogel for Spinal Cord Injury Treatment

Transplanting human induced pluripotent stem cells (iPSCs)-derived spinal cord progenitor cells (SCPCs) is a promising approach to treat spinal cord injuries. However, stem cell therapies face challenges in cell survival, cell localization to the targeted site, and the control of cell differentiation. Here, we encapsulated SCPCs in thiol-modified hyaluronan-gelatin hydrogels and optimized scaffold mechanical properties and cell encapsulation density to promote cell viability and neuronal differentiation in vitro and in vivo. Different compositions of hyaluronan-gelatin hydrogels formulated by varying concentrations of poly(ethylene glycol) diacrylate were mechanically characterized by using atomic force microscopy. In vitro SCPC encapsulation study showed higher cell viability and proliferation with lower substrate Young's modulus (200 Pa vs 580 Pa) and cell density. Moreover, the soft hydrogels facilitated a higher degree of neuronal differentiation with extended filament structures in contrast to clumped cellular morphologies obtained in stiff hydrogels (p < 0.01). When transplanted in vivo, the optimized SCPC-encapsulated hydrogels resulted in higher cell survival and localization at the transplanted region as compared to cell delivery without hydrogel encapsulation at 2 weeks postimplantation within the rat spinal cord (p < 0.01). Notably, immunostaining demonstrated that the hydrogel-encapsulated SCPCs differentiated along the neuronal and oligodendroglial lineages in vivo. The lack of pluripotency and proliferation also supported the safety of the SCPC transplantation approach. Overall, the injectable hyaluronan-gelatin hydrogel shows promise in supporting the survival and neural differentiation of human SCPCs after transplantation into the spinal cord.

Ferrostatin-1 facilitated neurological functional rehabilitation of spinal cord injury mice by inhibiting ferroptosis

BACKGROUND

To seek the potential therapy for spinal cord injury, Ferrostatin-1, the first ferroptosis inhibitor, was administrated in spinal cord injury mice to identify the therapeutic effect.

METHODS

Spinal cord injury model was established by a modified Allen's method. Then, ferrostatin-1 was administrated by intraspinal injection. Cortical evoked motor potential and BMS were indicated to assess the neurological function rehabilitation. H&E, Nissl's staining, NeuN, and GFAP immunofluorescence were used to identify the histological manifestation on the mice with the injured spinal cord. Spinosin, a selective small molecule activator of the Nrf2/HO-1 signaling pathway, was administrated to verify the underlying mechanism of ferrostatin-1.

RESULTS

Ferrostatin-1 promoted the rehabilitation of cortical evoked motor potential and BMS scores, synchronized with improvement in the histological manifestation of neuron survival and scar formation. Spinosin disturbed the benefits of ferrostatin-1 administration on histological and neurobehavioral manifestation by deranging the Nrf2/HO-1 signaling pathway.

CONCLUSIONS

Ferrostatin-1 improved the rehabilitation of spinal cord injury mice by regulating ferroptosis through the Nrf2/HO-1 signaling pathway.

The Impact of Biomaterial Surface Properties on Engineering Neural Tissue for Spinal Cord Regeneration

Tissue engineering for spinal cord injury (SCI) remains a complex and challenging task. Biomaterial scaffolds have been suggested as a potential solution for supporting cell survival and differentiation at the injury site. However, different biomaterials display multiple properties that significantly impact neural tissue at a cellular level. Here, we evaluated the behavior of different cell lines seeded on chitosan (CHI), poly (ε-caprolactone) (PCL), and poly (L-lactic acid) (PLLA) scaffolds. We demonstrated that the surface properties of a material play a crucial role in cell morphology and differentiation. While the direct contact of a polymer with the cells did not cause cytotoxicity or inhibit the spread of neural progenitor cells derived from neurospheres (NPCdn), neonatal rat spinal cord cells (SCC) and NPCdn only attached and matured on PCL and PLLA surfaces. Scanning electron microscopy and computational analysis suggested that cells attached to the material's surface emerged into distinct morphological populations. Flow cytometry revealed a higher differentiation of neural progenitor cells derived from human induced pluripotent stem cells (hiPSC-NPC) into glial cells on all biomaterials. Immunofluorescence assays demonstrated that PCL and PLLA guided neuronal differentiation and network development in SCC. Our data emphasize the importance of selecting appropriate biomaterials for tissue engineering in SCI treatment.

Multimodal therapy strategy based on a bioactive hydrogel for repair of spinal cord injury

Traumatic spinal cord injury results in permanent and serious neurological impairment, but there is no effective treatment yet. Tissue engineering approaches offer great potential for the treatment of SCI, but spinal cord complexity poses great challenges. In this study, the composite scaffold consists of a hyaluronic acid-based hydrogel, decellularized brain matrix (DBM), and bioactive compounds such as polydeoxyribonucleotide (PDRN), tumor necrosis factor-α/interferon-γ primed mesenchymal stem cell-derived extracellular vesicles (TI-EVs), and human embryonic stem cell-derived neural progenitor cells (NPC). The composite scaffold showed significant effects on regenerative prosses including angiogenesis, anti-inflammation, anti-apoptosis, and neural differentiation. In addition, the composite scaffold (DBM/PDRN/TI-EV/NPC@Gel) induced an effective spinal cord regeneration in a rat spinal cord transection model. Therefore, this multimodal approach using an integrated bioactive scaffold coupled with biochemical cues from PDRN and TI-EVs could be used as an advanced tissue engineering platform for spinal cord regeneration.

Bibliometric analysis of stem cells for spinal cord injury: current status and emerging frontiers

Background: This study aimed to conduct a bibliometric analysis of the literature on stem cell therapy for spinal cord injury to visualize the research status, identify hotspots, and explore the development trends in this field. Methods: We searched the Web of Science Core Collection database using relevant keywords ("stem cells" and "spinal cord injury") and retrieved the published literature between 2000 and 2022. Data such as journal title, author information, institutional affiliation, country, and keywords were extracted. Afterwards, we performed bibliometric analysis of the retrieved data using Bibliometrix, VOSviewer, and CiteSpace. Results: A total of 5375 articles related to stem cell therapy for spinal cord injury were retrieved, and both the annual publication volume and the cumulative publication volume showed an upward trend. neural regeneration research was the journal with the most publications and the fastest cumulative publication growth (162 articles), Okano Hideyuki was the author with the highest number of publications and citations (114 articles), Sun Yat-sen University was the institution with the highest number of publications (420 articles), and China was the country with the highest number of publications (5357 articles). However, different authors, institutions, and countries need to enhance their cooperation in order to promote the generation of significant academic achievements. Current research in this field has focused on stem cell transplantation, neural regeneration, motor function recovery, exosomes, and tissue engineering. Meanwhile, future research directions are primarily concerned with the molecular mechanisms, safety, clinical trials, exosomes, scaffolds, hydrogels, and inflammatory responses of stem cell therapy for spinal cord injuries. Conclusion: In summary, this study provided a comprehensive analysis of the current research status and frontiers of stem cell therapy for spinal cord injury. The findings provide a foundation for future research and clinical translation efforts of stem cell therapy in this field.

Collagen for neural tissue engineering: Materials, strategies, and challenges

Neural tissue engineering (NTE) has made remarkable strides in recent years and holds great promise for treating several devastating neurological disorders. Selecting optimal scaffolding material is crucial for NET design strategies that enable neural and non-neural cell differentiation and axonal growth. Collagen is extensively employed in NTE applications due to the inherent resistance of the nervous system against regeneration, functionalized with neurotrophic factors, antagonists of neural growth inhibitors, and other neural growth-promoting agents. Recent advancements in integrating collagen with manufacturing strategies, such as scaffolding, electrospinning, and 3D bioprinting, provide localized trophic support, guide cell alignment, and protect neural cells from immune activity. This review categorises and analyses collagen-based processing techniques investigated for neural-specific applications, highlighting their strengths and weaknesses in repair, regeneration, and recovery. We also evaluate the potential prospects and challenges of using collagen-based biomaterials in NTE. Overall, this review offers a comprehensive and systematic framework for the rational evaluation and applications of collagen in NTE.

Incidence and risk factors of deep vein thrombosis in patients with spinal cord injury: a systematic review with meta-analysis

Background

Spinal cord injury (SCI) is a highly disabling disease with huge public health burden. The complications associated with it, especially deep vein thrombosis (DVT), further aggravate the disability.

Objective

To explore the incidence and risk factors of DVT after SCI, in order to provide guidance for disease prevention in the future.

Methods

A search was performed on PubMed, Web of Science, Embase, and Cochrane database up to November 9, 2022. Literature screening, information extraction and quality evaluation were performed by two researchers. The data was later combined by metaprop and metan commands in STATA 16.0.

Results

A total of 101 articles were included, including 223,221 patients. Meta-analysis showed that the overall incidence of DVT was 9.3% (95% CI: 8.2%-10.6%), and the incidence of DVT in patients with acute and chronic SCI was 10.9% (95% CI: 8.7%-13.2%) and 5.3% (95% CI: 2.2%-9.7%), respectively. The incidence of DVT decreased gradually with the accumulation of publication years and sample size. However, the annual incidence of DVT has increased since 2017. There are 24 kinds of risk factors that may contribute to the formation of DVT, involving multiple aspects of the baseline characteristics of the patient, biochemical indicators, severity of SCI, and comorbidities.

Conclusions

The incidence of DVT after SCI is high and has been gradually increasing in recent years. Moreover, there are numerous risk factors associated with DVT. Comprehensive preventive measures need to be taken as early as possible in the future.

Systematic Review Registration

www.crd.york.ac.uk/prospero, identifier CRD42022377466.

Gelatin methacryloyl hydrogel scaffold loaded with activated Schwann cells attenuates apoptosis and promotes functional recovery following spinal cord injury

Spinal cord injury (SCI) is a refractory disease of the central nervous system with a high disability and incidence rate. In recent years, bioactive material combined with cell transplantation has been considered an effective method for the treatment of SCI. The present study encapsulated activated Schwann cells (ASCs) in a 3D gelatin methacryloyl (GelMA) hydrogel in order to investigate its therapeutic effects on SCI. ASCs were isolated from previously ligated rat sciatic nerves. Scanning electron microscopy and live/dead staining were used to evaluate the biocompatibility of hydrogels with the ASCs. The scaffold was transplanted into the spinal cord of rats in the hemisection model. Behavioral tests and hematoxylin and eosin staining were employed to assess the locomotion recovery and lesion areas before and after treatment. Cell apoptosis was evaluated using TUNEL staining and immunochemistry, and apoptosis-related protein expression was detected using western blot analysis. The ASCs exhibited a favorable survival and proliferative ability in the 3D GelMA hydrogel. The scaffold transplantation significantly reduced the cavities and improved functional recovery. Moreover, the GelMA/ASCs implants significantly inhibited cell apoptosis following SCI and this effect may be mediated via the p38 MAPK pathway. Overall, these findings indicated that ASCs combined with the 3D GelMA hydrogel may be a promising therapeutic strategy for SCI.

Exosomes combined with biomaterials in the treatment of spinal cord injury

Spinal cord injury (SCI) is a serious and disabling disease with a high mortality rate. It often leads to complete or partial sensory and motor dysfunction and is accompanied by a series of secondary outcomes, such as pressure sores, pulmonary infections, deep vein thrombosis in the lower extremities, urinary tract infections, and autonomic dysfunction. Currently, the main treatments for SCI include surgical decompression, drug therapy, and postoperative rehabilitation. Studies have shown that cell therapy plays a beneficial role in the treatment of SCI. Nonetheless, there is controversy regarding the therapeutic effect of cell transplantation in SCI models. Meanwhile exosomes, as a new therapeutic medium for regenerative medicine, possess the advantages of small size, low immunogenicity, and the ability to cross the blood-spinal cord barrier. Certain studies have shown that stem cell-derived exosomes have anti-inflammatory effects and can play an irreplaceable role in the treatment of SCI. In this case, it is difficult for a single treatment method to play an effective role in the repair of neural tissue after SCI. The combination of biomaterial scaffolds and exosomes can better transfer and fix exosomes to the injury site and improve their survival rate. This paper first reviews the current research status of stem cell-derived exosomes and biomaterial scaffolds in the treatment of SCI respectively, and then describes the application of exosomes combined with biomaterial scaffolds in the treatment of SCI, as well as the challenges and prospects.

Spinal Cord-Gut-Immune Axis and its Implications Regarding Therapeutic Development for Spinal Cord Injury

Spinal cord injury (SCI) affects ∼1,300,000 people living in the United States. Most research efforts have been focused on reversing paralysis, as this is arguably the most defining feature of SCI. The damage caused by SCI, however, extends past paralysis and includes other debilitating outcomes including immune dysfunction and gut dysbiosis. Recent efforts are now investigating the pathophysiology of and developing therapies for these more distal manifestations of SCI. One exciting avenue is the spinal cord-gut-immune axis, which proposes that gut dysbiosis amplifies lesion inflammation and impairs SCI recovery. This review will highlight the most recent findings regarding gut and immune dysfunction following SCI, and discuss how the central nervous system (CNS), gut, and immune system all coalesce to form a bidirectional axis that can impact SCI recovery. Finally, important considerations regarding how the spinal cord-gut-immune axis fits within the larger framework of therapeutic development (i.e., probiotics, fecal transplants, dietary modifications) will be discussed, emphasizing the lack of interdepartmental investigation and the missed opportunity to maximize therapeutic benefit in SCI.

The application of 3D-bioprinted scaffolds for neuronal regeneration after traumatic spinal cord injury - A systematic review of preclinical in vivo studies

BACKGROUND

The implantation of 3D-bioprinted scaffolds represents a promising therapeutic approach for traumatic Spinal Cord Injury (SCI), currently investigating in preclinical in vivo studies. However, a systematic review of the relevant literature has not been performed to date. Hence, we systematically reviewed the outcomes of the application of 3D-bioprinted implants in the treatment of SCI based on studies conducted on experimental animal models.

METHODS

We searched PubMed, Scopus, Web of Science, and Cochrane Library databases. Manuscripts in other designs than in vivo preclinical study and written in other languages than English were excluded. A risk of bias assessment was performed using SYRCLE's tool. The quality of included articles was assessed by ARRIVE guidelines. Extracted data were synthesized only qualitatively because the data were not suitable for conducting the meta-analysis.

RESULTS

Overall, eleven animal studies reporting on the transection SCI rat model were included. Six of included studies investigated 3D-bioprinted scaffolds enriched with stem cells, two studies - 3D-bioprinted scaffolds combined with growth factors, and three studies - stand-alone 3D-bioprinted scaffolds. In all included studies the application of 3D-bioprinted scaffolds led to significant improvement in functional scores compared with no treated SCI rats. The functional recovery corresponded with the changes observed at the injury site in histological analyses. Seven studies demonstrated medium, three studies - high, and one study - low risk of bias. Moreover, some of the included studies were conducted in the same scientific center. The overall quality assessment ratio amounted to 0.60, which was considered average quality.

CONCLUSION

The results of our systematic review suggest that 3D-bioprinted scaffolds may be a feasible therapeutic approach for the treatment of SCI. Further evidence obtained on other experimental SCI models is necessary before the clinical translation of 3D-bioprinted scaffolds.