Cell transplantation therapy for spinal cord injury

Differential response of injured and healthy retinas to syngeneic and allogeneic transplantation of a clonal cell line of immortalized olfactory ensheathing glia: a double-edged sword

JOURNAL/nrgr/04.03/01300535-202508000-00029/figure1/v/2024-09-30T120553Z/r/image-tiff Olfactory ensheathing glia promote axonal regeneration in the mammalian central nervous system, including retinal ganglion cell axonal growth through the injured optic nerve. Still, it is unknown whether olfactory ensheathing glia also have neuroprotective properties. Olfactory ensheathing glia express brain-derived neurotrophic factor, one of the best neuroprotectants for axotomized retinal ganglion cells. Therefore, we aimed to investigate the neuroprotective capacity of olfactory ensheating glia after optic nerve crush. Olfactory ensheathing glia cells from an established rat immortalized clonal cell line, TEG3, were intravitreally injected in intact and axotomized retinas in syngeneic and allogeneic mode with or without microglial inhibition or immunosuppressive treatments. Anatomical and gene expression analyses were performed. Olfactory bulb-derived primary olfactory ensheathing glia and TEG3 express major histocompatibility complex class II molecules. Allogeneically and syngenically transplanted TEG3 cells survived in the vitreous for up to 21 days, forming an epimembrane. In axotomized retinas, only the allogeneic TEG3 transplant rescued retinal ganglion cells at 7 days but not at 21 days. In these retinas, microglial anatomical activation was higher than after optic nerve crush alone. In intact retinas, both transplants activated microglial cells and caused retinal ganglion cell death at 21 days, a loss that was higher after allotransplantation, triggered by pyroptosis and partially rescued by microglial inhibition or immunosuppression. However, neuroprotection of axotomized retinal ganglion cells did not improve with these treatments. The different neuroprotective properties, different toxic effects, and different responses to microglial inhibitory treatments of olfactory ensheathing glia in the retina depending on the type of transplant highlight the importance of thorough preclinical studies to explore these variables.

A review: Carrier-based hydrogels containing bioactive molecules and stem cells for ischemic stroke therapy

Ischemic stroke (IS), a cerebrovascular disease, is the leading cause of physical disability and death worldwide. Tissue plasminogen activator (tPA) and thrombectomy are limited by a narrow therapeutic time window. Although strategies such as drug therapies and cellular therapies have been used in preclinical trials, some important issues in clinical translation have not been addressed: low stem cell survival and drug delivery limited by the blood-brain barrier (BBB). Among the therapeutic options currently sought, carrier-based hydrogels hold great promise for the repair and regeneration of neural tissue in the treatment of ischemic stroke. The advantage lies in the ability to deliver drugs and cells to designated parts of the brain in an injectable manner to enhance therapeutic efficacy. Here, this article provides an overview of the use of carrier-based hydrogels in ischemic stroke therapy and focuses on the use of hydrogel scaffolds containing bioactive molecules and stem cells. In addition to this, we provide a more in-depth summary of the composition, physicochemical properties and physiological functions of the materials themselves. Finally, we also outline the prospects and challenges for clinical translation of hydrogel therapy for IS.

Conjugated therapy with coaxially printed neural stem cell-laden microfibers and umbilical cord mesenchymal stem cell derived exosomes on complete transactional spinal cord defects

Motor function recovery after complete spinal cord injury remained as a challenge in medical field, while one of the key approaches is promoting the local microenvironments. In this research, we performed a conjugated therapy by transplantation of neural stem cell (NSC) scaffolds and umbilical cord mesenchymal stem cell derived exosomes (ucMSC-exos) for the treatment of complete transactional spinal cord injury (SCI). We first demonstrated the anti-inflammatory effects of ucMSC-exos in vitro and found that ucMSC-exos could regulate microglia polarization from M1 to M2, an anti-inflammatory phenotype. Besides, ucMSC-exos also promoted NSC proliferation and neural differentiation during in vitro culturing. On the other hand, core-shell hydrogel microfibers were used as transplantation scaffolds for both small and large SCI defects. The core-shell microfibers could carry large amounts of NSCs in the core portion and the shell portion is highly permeable for nutrient and metabolite transportation. In in vivo experiments, we found that conjugated transplantation of ucMSC-exos and NSC microfibers could decreased inflammatory cytokines at lesion sites, gave rise to more neurons and promoted angiogenesis, thus comprehensively improved the local microenvironment while compared with transplantation of NSC scaffolds only. These beneficial results were in accordance with those in vitro experiments and further led to better locomotor function recovery. In summary, this research has demonstrated that that conjugated transplantation of ucMSC-exos and NSC microfibers could make a potential tool for complete SCI repair.

Cell Therapy and the Skin: Great Potential but in Need of Optimization

Cell therapy is rapidly growing owing to its therapeutic potential for diseases with currently poor outcomes. Cell therapy encompasses both nonengineered and engineered cells and possesses unique abilities such as sense-and-respond functions and long-term engraftment for persistent curative potential. Cell therapy capabilities have expanded to address a wide spectrum of diseases, and our review is focused on dermatological applications. The use of fibroblasts and keratinocytes as cell therapy has shown promise in skin disorders such as epidermolysis bullosa. Future efforts include testing the ability of fibroblasts to reprogram nonvolar to volar skin to reduce stump dermatoses in patients with limb loss using prosthetics.

Graphene oxide scaffolds promote functional improvements mediated by scaffold-invading axons in thoracic transected rats

Millions of patients and their caretakers live and deal with the devastating consequences of spinal cord injury (SCI) worldwide. Despite outstanding advances in the field to both understand and tackle these pathologies, a cure for SCI patients, with their peculiar characteristics, is still a mirage. One of the most promising therapeutic strategies to date for these patients involves the use of epidural electrical stimulation. In this context, electrically active materials such as graphene and its derivates become particularly interesting. Indeed, solid evidence of their capacity to closely interact with neural cells and networks is growing. Encouraged by previous findings in our laboratory on the exploration of 3D porous reduced graphene oxide (rGO) scaffolds in chronic cervical hemisected rats (C6), herein we report their neuro-reparative properties when chronically implanted in complete transected rats (T9-T10), in which no preserved contralateral neural networks can assist in any observed recovery. Electrophysiological recordings from brainstem regions show antidromic activation of a small population of neurons in response to electrical stimulation caudal to the injury. These neurons are located in the Gigantocellular nucleus of reticular formation and vestibular nuclei, both regions directly related to motor functions. Together with histological features at the lesion site, such as more abundant and larger blood vessels and more abundant, longer and more homogeneously distributed axons, our results corroborate that rGO scaffolds create a permissive environment that allows the invasion of functional axonic processes from neurons located in brainstem nuclei with motor function in a rat model of complete thoracic transection. Additionally, behavioral tests evidence that these scaffolds play an important role in whole-body mechanical stabilization (postural control) proved by the absence of scoliosis, a higher trunk stability and a larger cervico-thoraco-lumbar movement range in rGO-implanted rats.

Harnessing stem cell-derived exosomes: a promising cell-free approach for spinal cord injury

Spinal cord injury (SCI) is a severe injury to the central nervous system that often results in permanent neurological dysfunction. Current treatments have limited efficacy and face challenges in restoring neurological function after injury. Recently, stem cell-derived exosomes have gained attention as an experimental treatment for SCI due to their unique properties, including superior biocompatibility, minimal immunogenicity and non-tumorigenicity. With their potential as a cell-free therapy, exosomes promote SCI repair by enhancing nerve regeneration, reducing inflammation and stabilizing the blood-spinal cord barrier. This review summarizes advances in stem cell-derived exosome research for SCI over the past years, focusing on their mechanisms and future prospects. Despite their promising therapeutic potential, clinical translation remains challenging due to standardization of exosome isolation protocols, compositional consistency and long-term safety profiles that require further investigation.

Compact transcription factor cassettes generate functional, engraftable motor neurons by direct conversion

Direct conversion generates patient-specific, disease-relevant cell types, such as neurons, that are rare, limited, or difficult to isolate from common and easily accessible cells, such as skin cells. However, low rates of direct conversion and complex protocols limit scalability and, thus, the potential of cell-fate conversion for biomedical applications. Here, we optimize the conversion protocol by examining process parameters, including transcript design; delivery via adeno-associated virus (AAV), retrovirus, and lentivirus; cell seeding density; and the impact of media conditions. Thus, we report a compact, portable conversion process that boosts proliferation and increases direct conversion of mouse fibroblasts to induced motor neurons (iMNs) to achieve high conversion rates of above 1,000%, corresponding to more than ten motor neurons yielded per cell seeded, which we achieve through expansion. Our optimized, direct conversion process generates functional motor neurons at scales relevant for cell therapies (>107 cells) that graft with the mouse central nervous system. High-efficiency, compact, direct conversion systems will support scaling to patient-specific, neural cell therapies.

Exploring Innovative Approaches for Managing Spinal Cord Injury: A Comprehensive Review of Promising Probiotics and Postbiotics

Spinal cord injury (SCI) affects millions of people worldwide annually, presenting significant challenges in functional recovery despite therapeutic advancements. Current treatment strategies predominantly focus on stabilizing the spinal cord and facilitating neural repair, yet their effectiveness remains uncertain and controversial. Recent scientific investigations have explored the potential of probiotics and postbiotics to modulate inflammation, influence neurotransmitters, and aid in tissue repair, marking a potential paradigm shift in SCI management. This review critically evaluates these innovative approaches, emphasizing their ability to harness the natural properties of microorganisms within the body to potentially enhance outcomes in SCI treatment. By analyzing the latest research findings, this review provides valuable insights into how probiotics and postbiotics can revolutionize inflammation management and neurological recovery following SCI, underscoring their promising role in future therapeutic strategies aimed at improving the quality of life of SCI patients globally.

5-year follow-up of a fully implanted brain-computer interface in a spinal cord injury patient

Spinal cord injury (SCI) affects over 250 000 individuals in the US. Brain-computer interfaces (BCIs) may improve quality of life by controlling external devices. Invasive intracortical BCIs have shown promise in clinical trials but degrade in the chronic period and tether patients to acquisition hardware. Alternatively, electrocorticography (ECoG) records data from electrodes on the cortex,and studies evaluating fully implanted BCI-ECoG systems are scarce. Objective. We seek to address this need using a fully implanted ECoG-based BCI that allows for home use in SCI.Approach.The patient used a long-term BCI system, initially controlling an functional electrical stimulation orthosis in the lab and later using an external mechanical orthosis at home. To evaluate its long-term viability, electrode contact impedance, signal quality, and decoder performance were measured. Signal quality was assessed using signal-to-noise ratio and maximum bandwidth of the signal. Decoder performance was monitored using the area under the receiver operator characteristic curve (AUROC).Main results.The study analyzed data from the patient's home environment over 54 months, revealing that the device was used at home for 38 ± 24 min on average daily. After six months, we observed stable event-related desynchronization that aided in determining the onset of motor intention. The decoder's average AUROC across months was 0.959. Importantly, 40 months of the data collected was gather from the subject's home or community environment. The results indicate long-term ECoG recordings were stable for motor-imagery classification and motor control in the community environment in a case of an individual with SCI.Significance.This study presents the long-term feasibility and viability of an ECoG-based BCI system that persists in the home environment in a case of SCI. Future research should explore larger electrode counts with more participants to confirm this stability. Understanding these trends is crucial for clinical utility and chronic viability in broader patient populations.

Functional synaptic connectivity of engrafted spinal cord neurons with locomotor circuitry in the injured spinal cord

Spinal cord injury (SCI) results in significant neurological deficits, with no currently available curative therapies. Neural progenitor cell (NPC) transplantation has emerged as a promising approach for neural repair, as graft-derived neurons (GDNs) can integrate into the host spinal cord and support axon regeneration. However, the mechanisms underlying functional recovery remain poorly understood. In this study, we investigate the synaptic integration of NPC-derived neurons into locomotor circuits, the projection patterns of distinct neuronal subtypes, and their potential to modulate motor circuit activity. Using transsynaptic tracing in a mouse thoracic contusion SCI model, we found that NPC-derived neurons form synaptic connections with host locomotor circuits, albeit at low frequencies. Furthermore, we mapped the axon projections of V0C and V2a interneurons, revealing distinct termination patterns within host spinal cord laminae. To assess functional integration, we employed chemogenetic activation of GDNs, which induced muscle activity in a subset of transplanted animals. However, NPC transplantation alone did not significantly improve locomotor recovery, highlighting a key challenge in the field. Our findings suggest that while GDNs can integrate into host circuits and modulate motor activity, synaptic connectivity remains a limiting factor in functional recovery. Future studies should focus on enhancing graft-host connectivity and optimizing transplantation strategies to maximize therapeutic benefits for SCI.

An engineering-reinforced extracellular vesicle-integrated hydrogel with an ROS-responsive release pattern mitigates spinal cord injury

The local delivery of mesenchymal stem cell-derived extracellular vesicles (EVs) via hydrogel has emerged as an effective approach for spinal cord injury (SCI) treatment. However, achieving on-demand release of EVs from hydrogel to address dynamically changing pathology remains challenging. Here, we used a series of engineering methods to further enhance EVs' efficacy and optimize their release pattern from hydrogel. Specifically, the pro-angiogenic, neurotrophic, and anti-inflammatory effects of EVs were reinforced through three-dimensional culture and dexamethasone (Dxm) encapsulation. Then, the prepared Dxm-loaded 3EVs (3EVs-Dxm) were membrane modified with ortho-dihydroxy groups (-2OH) and formed an EV-integrated hydrogel (3EVs-Dxm-Gel) via the cross-link with phenylboronic acid-modified hyaluronic acid and tannic acid. The phenylboronic acid ester in 3EVs-Dxm-Gel enabled effective immobilization and reactive oxygen species-responsive release of EVs. Topical injection of 3EVs-Dxm-Gel in SCI rats notably mitigated injury severity and promoted functional recovery, which may offer opportunities for EV-based therapeutics in central nervous system injury.

Harnessing spinal circuit reorganization for targeted functional recovery after spinal cord injury

Spinal cord injury (SCI) disrupts the communication between the brain and spinal cord, resulting in the loss of motor function below the injury site. However, spontaneous structural and functional plasticity occurs in neural circuits after SCI, with unaffected synaptic inputs forming new connections and detour pathways to support recovery. The review discusses various mechanisms of circuit reorganization post-SCI, including supraspinal pathways, spinal interneurons, and spinal central pattern generators. Functional recovery may rely on maintaining a balance between excitatory and inhibitory neural activity, as well as enhancing proprioceptive input, which plays a key role in limb stability. The review emphasizes the importance of endogenous neuronal regeneration, neuromodulation therapies (such as electrical stimulation) and proprioception in SCI treatment. Future research should integrate advanced technologies such as gene targeting, imaging, and single-cell mapping to better understand the mechanisms underpinning SCI recovery, aiming to identify key neuronal subpopulations for targeted reconstruction and enhanced functional recovery. By harnessing spinal circuit reorganization, these efforts hold the potential to pave the way for more precise and effective strategies for functional recovery after SCI.

Designing hydrogel for application in spinal surgery

Spinal diseases and injuries are prevalent in clinical settings and impose a substantial burden on healthcare systems. Current treatments for spinal diseases are predominantly limited to surgical interventions, drug injections, and conservative treatments. Generally, these treatment modalities have limited or no long-term benefits. Hydrogel-based treatments have emerged as potentially powerful paradigms for improving therapeutic outcomes and the quality of life of patients. Hydrogels can be injected into target sites, including the epidural, intraspinal, and nucleus pulposus spaces, in a minimally invasive manner and fill defects to provide mechanical support. Hydrogels can be designed for the localized and controlled delivery of pharmacological agents to enhance therapeutic effects and reduce adverse reactions. Hydrogels can act as structural supports for transplanted cells to improve cell survival, proliferation, and differentiation, as well as integration into adjacent host tissues. In this review, we summarize recent advances in the design of hydrogels for the treatment of spinal diseases and injuries commonly found in clinical settings, including intervertebral disc degeneration, spinal cord injury, and dural membrane injury. We introduce the design considerations for different hydrogel systems, including precursor polymers and crosslinking mechanisms. Herein, we discuss the therapeutic outcomes of these hydrogels in terms of providing mechanical support, delivering cells/bioactive agents, regulating local inflammation, and promoting tissue regeneration and functional recovery.

Synergistic restoration of spinal cord injury through hyaluronic acid conjugated hydrogel-polydopamine nanoparticles combined with human mesenchymal stem cell transplantation

Spinal cord injury (SCI) is a devastating disease with limited treatment options due to the restricted regenerative capacity of the central nervous system. The accumulation of reactive oxygen species (ROS) and inadequate endogenous neural stem progenitor cells (eNSPCs) in the lesion site exacerbates neurologic deficits and impedes motor function recovery. We have developed a temperature-responsive hyaluronic acid conjugated hydrogel-polydopamine nanoparticles (PDA NPs) combined with human mesenchymal stem cell (hMSCs) transplantation, denoted as H-P-M hydrogel. Microglia cells treated with PDA NPs have been shown to reduce intracellular ROS levels by 65 % and suppress the expression of inflammatory cytokines such as IL-1β (decreased by 35 %) and IL-6 (decreased by 23 %), thus mitigating the microglia's inflammatory response. Additionally, our results have demonstrated that the H-P-M hydrogel combined with hMSCs transplantation can recruit eNSPCs to the injury site as evidenced by utilizing Nestin lineage tracer mice. The RNA-seq has unveiled the potential of the H-P-M hydrogel to facilitate eNSPCs neuronal differentiation through the MAPK pathway. Furthermore, these differentiated neurons are integrated into local neural circuits. Together, it suggests that the H-P-M hydrogel synergistically improves the SCI niche. It serves as catalysts inducing 5-HT axon regeneration and improving BMS score after SCI through the modulation of the ROS milieu and the promotion of neuronal differentiation from eNSPCs, thereby presenting a promising strategy for SCI repair.

Spinal cord injury repair based on drug and cell delivery: From remodeling microenvironment to relay connection formation

Spinal cord injury (SCI) presents a formidable challenge in clinical settings, resulting in sensory and motor function loss and imposing significant personal and societal burdens. However, owning to the adverse microenvironment and limited regenerative capacity, achieving complete functional recovery after SCI remains elusive. Additionally, traditional interventions including surgery and medication have a series of limitations that restrict the effectiveness of treatment. Recently, tissue engineering (TE) has emerged as a promising approach for promoting neural regeneration and functional recovery in SCI, which can effectively delivery drugs into injury site and delivery cells and improve the survival and differential. Here, we outline the main pathophysiology events of SCI and the adverse microenvironment post injury, further discuss the materials and common assembly strategies used for scaffolds in SCI treatment, expound on the latest advancements in treatment methods based on materials and scaffolds for drug and cell delivery in detail, and propose future directions for SCI repair with TE and highlight potential clinical applications.

Intranasal Delivery of Brain-Derived Neurotrophic Factor (BDNF)-Loaded Small Extracellular Vesicles for Treating Acute Spinal Cord Injury in Rats and Monkeys

Besides surgical decompression, neuroprotection and neuroinflammation reduction are critical for acute spinal cord injury (SCI). In this study, we prepared small extracellular vesicles (sEVs) from immortalised mesenchymal stem cells overexpressing brain-derived neurotrophic factor (BDNF) and evaluated whether intranasal administration of BDNF-sEVs is a therapeutic option for acute SCI. In cultured neurons, BDNF loading enhanced neurite outgrowth promoted by sEVs. After intranasal administration, mCherry-labelled sEVs were transported to the injured spinal cords of rats and monkeys and mainly taken up by neurons. In acute SCI rats, intranasal administration of sEVs and BDNF-sEVs reduced glial responses and proinflammatory cytokine production, enhanced neuronal survival and angiogenesis in the lesion, promoted injured axon rewiring, delayed lumbar spinal motoneuron atrophy below the lesion, and improved functional performance. The rats receiving BDNF-sEV treatment showed improved neural repair and functional recovery compared to those with sEV treatment. Intranasal administration of BDNF-sEVs, but not of sEVs, increased BDNF levels and phosphorylation of downstream signals in the rat-injured spinal cord samples, indicating activation of the BDNF/TrkB signalling pathway. In acute SCI monkeys, intranasal administration of BDNF-sEVs was further confirmed to inhibit glial reactivities and proinflammatory cytokine release, increasing BDNF levels in the cerebrospinal fluid, enhancing neural network rewiring of injured spinal cords and neuronal activities of the brain, and improving functional performances in behavioural tests and electrophysiological recordings. In conclusion, BDNF-sEVs play a combinatory therapeutic role of sEVs and BDNF, and intranasal administration of BDNF-sEVs is a potential option for the clinical treatment of acute SCI.

Macrophage-targeted Mms6 mRNA-lipid nanoparticles promote locomotor functional recovery after traumatic spinal cord injury in mice

Traumatic spinal cord injury (SCI) causes severe central nervous system damage. M2 macrophages within the lesion are crucial for SCI recovery. Our previous research revealed that M2 macrophages transfected with magnetotactic bacteria-derived Mms6 gene can resist ferroptosis and enhance SCI recovery. To address the limitations of M2 macrophage transplantation, we developed lipid nanoparticles (LNPs) encapsulating Mms6 mRNA targeting macrophages (Mms6 mRNA-PS/LNPs). The targeting efficiency and therapeutic effect of these LNPs in SCI mice were evaluated. Intravenous administration of Mms6 mRNA-PS/LNPs delivered more Mms6 mRNAs to lesion-site macrophages than those in the Mms6 mRNA-LNP group, which resulted in enhancing motor function recovery, reducing lesion area and scar formation, and promoting neuronal survival and nerve fiber repair. These effects were nullified when macrophages were depleted. These findings suggest that macrophage-targeted delivery of Mms6 mRNA is a promising therapeutic strategy for promoting spinal cord repair and motor function recovery in patients with traumatic SCI.

Graphene-based materials: an innovative approach for neural regeneration and spinal cord injury repair

Spinal cord injury (SCI), the most serious disease affecting the central nervous system (CNS), is one of contemporary medicine's most difficult challenges, causing patients to suffer physically, emotionally, and socially. However, due to recent advances in medical science and biomaterials, graphene-based materials (GBMs) have tremendous potential in SCI therapy due to their wonderful and valuable properties, such as physicochemical properties, extraordinary electrical conductivity, distinct morphology, and high mechanical strength. This review discusses SCI pathology and GBM characteristics, as well as recent in vitro and in vivo findings on graphenic scaffolds, electrodes, and injectable achievements for SCI improvement using neuroprotective and neuroregenerative techniques to improve neural structural and functional repair. Additionally, it suggests possible ideas and desirable products for graphene-based technological advances, intending to reach therapeutic importance for SCI.

Physical stimuli-responsive DNA hydrogels: design, fabrication strategies, and biomedical applications

Physical stimuli-responsive DNA hydrogels hold immense potential for tissue engineering due to their inherent biocompatibility, tunable properties, and capacity to replicate the mechanical environment of natural tissue, making physical stimuli-responsive DNA hydrogels a promising candidate for tissue engineering. These hydrogels can be tailored to respond to specific physical triggers such as temperature, light, magnetic fields, ultrasound, mechanical force, and electrical stimuli, allowing precise control over their behavior. By mimicking the extracellular matrix (ECM), DNA hydrogels provide structural support, biomechanical cues, and cell signaling essential for tissue regeneration. This article explores various physical stimuli and their incorporation into DNA hydrogels, including DNA self-assembly and hybrid DNA hydrogel methods. The aim is to demonstrate how DNA hydrogels, in conjunction with other biomolecules and the ECM environment, generate dynamic scaffolds that respond to physical stimuli to facilitate tissue regeneration. We investigate the most recent developments in cancer therapies, including injectable DNA hydrogel for bone regeneration, personalized scaffolds, and dynamic culture models for drug discovery. The study concludes by delineating the remaining obstacles and potential future orientations in the optimization of DNA hydrogel design for the regeneration and reconstruction of tissue. It also addresses strategies for surmounting current challenges and incorporating more sophisticated technologies, thereby facilitating the clinical translation of these innovative hydrogels.

Efficacy of Deferoxamine Mesylate in Serum and Serum-Free Media: Adult Ventral Root Schwann Cell Survival Following Hydrogen Peroxide-Induced Cell Death

Schwann cell (SC) transplantation shows promise in treating spinal cord injury as a pro-regenerative agent to allow host endogenous neurons to bridge over the lesion. However, SC transplants face significant oxidative stress facilitated by ROS in the lesion, leading to poor survival. deferoxamine mesylate (DFO) is a neuroprotective agent shown to reduce H2O2-induced cell death in serum-containing conditions. Here we show that DFO is not necessary to induce neuroprotection under serum-free conditions by cell survival quantification and phenotypic analysis via immunohistochemistry, Hif1α and collagen IV quantification via whole cell corrected total cell fluorescence, and cell death transcript changes via RT-qPCR. Our results indicate survival of SC regardless of DFO pretreatment in serum-free conditions and an increased survival facilitated by DFO in serum-containing conditions. Furthermore, our results showed strong nuclear expression of Hif1α in serum-free conditions regardless of DFO pre-treatment and a nuclear expression of Hif1α in DFO-treated SCs in serum conditions. Transcriptomic analysis reveals upregulation of autophagy transcripts in SCs grown in serum-free media relative to SCs in serum conditions, with and without DFO and H2O2. Thus, indicating a pro-repair and regenerative state of the SCs in serum-free conditions. Overall, results indicate the protectiveness of CDM in enhancing SC survival against ROS-induced cell death in vitro.

Cerebrospinal fluid-contacting neurons: a promising source for adult neural stem cell transplantation in spinal cord injury treatment

Transplantation of adult neural stem cells (NSCs) is regarded as one of the most promising approaches for treating spinal cord injury (SCI). However, securing a sufficient and reliable source of adult NSCs remains one of the primary challenges in applying this method for SCI treatment. Cerebrospinal fluid-contacting neurons (CSF-cNs) act as adult NSCs and can be substantially expanded in vitro while maintaining their NSC characteristics even after 60 passages. When CSF-cNs are transplanted into the injury sites of SCI mice, they demonstrate high survival rates along with the ability to proliferate and differentiate into neurons, astrocytes, and oligodendrocytes. Additionally, significant improvements in motor function have been observed in SCI mice following the transplantation of CSF-cNs. These results suggest that CSF-cNs may represent a promising source of adult NSCs for transplantation therapy in SCI.

NLRP3 inflammasome promotes functional repair after spinal cord injury in mice by regulating autophagy and its mechanism

BACKGROUND

Inflammation at the injury site exacerbates tissue cell death following a spinal cord injury (SCI). Studies show that NLRP3 inflammasomes are crucial in the inflammation following Spinal Cord Injury, and NLRP3 inflammasomes have been shown to promote cells to undergo excessive autophagy in other diseases. Moreover, excessive autophagy levels could hinder functional repair post-SCI. In this regard, we hypothesized that inhibiting NLRP3 inflammasomes could reduce autophagy levels at the injury site, thus promoting functional repair post-SCI.

METHODS

Herein, a mouse SCI model was used for in vivo experiments, and an in vitro neuroinflammatory model created using LPS-activated BV2 cells was used for in vitro experiments. Histopathological staining was used to assess tissue repair. Western Blot (WB) and quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) were used to detect changes in relevant autophagy molecules, macrophage polarization-related markers and downstream inflammatory factors, and Immunofluorescence (IF) was used to detect changes in macrophage polarization.

RESULTS

Following SCI, the inhibition of NLRP3 inflammasomes resulting from intraperitoneal injection of MCC950 significantly reduced autophagy levels at the injury site, resulting in both histological and behavioral improvements. In addition, the phosphorylation of mTOR during inhibition of NLRP3 inflammasomes to reduce autophagy levels further improved the immune microenvironment at the injury site, and M2-type macrophages were significantly upregulated M2-type macrophages. Moreover, in vitro experiments yielded results consistent with those of in vivo experiments regarding changes in autophagy-related indexes and polarization-related markers.

CONCLUSIONS

Inhibition of NLRP3 inflammasomes can reduce autophagy level at the injury site to promote functional recovery and play a neuroprotective role. Moreover, phosphorylation of mTOR during the process of inhibition of NLRP3 inflammasomes to reduce autophagy, leading to reduced autophagy levels, could improve the immune microenvironment at the injury site, thus promoting functional recovery and histopathological repair post-SCI.

Generation of phenotypically stable and functionally mature human bone marrow MSCs derived Schwann cells via the induction of human iPSCs-derived sensory neurons

BACKGROUND

Phenotypically unstable Schwann cell-like cells (SCLCs), derived from mesenchymal stem cells (MSCs) require intercellular contact-mediated cues for Schwann cell (SCs)-fate commitment. Although rat dorsal root ganglion (DRG) neurons provide contact-mediated signals for the conversion of SCLCs into fate-committed SCs, the use of animal cells is clinically unacceptable. To overcome this problem, we previously acquired human induced pluripotent stem cell-derived sensory neurons (hiPSC-dSNs) as surrogates of rat DRG neurons that committed rat bone marrow SCLCs to the SC fate. In this study, we explored whether hiPSC-dSNs could mimic rat DRG neuron effects to obtain fate-committed SCs from hBMSC-derived SCLCs.

METHODS

hiPSCs were induced into hiPSC-dSNs using a specific chemical small molecule combination. hBMSCs were induced into hBMSC-derived SCLCs in a specific culture medium and then co-cultured with hiPSC-dSNs to generate SCs. The identity of hBMSC-derived SCs (hBMSC-dSCs) was examined by immunofluorescence, western bolt, electronic microscopy, and RNA-seq. Immunofluorescence was also used to detect the myelination capacity. Enzyme-linked immunosorbent assay and neurite outgrowth analysis were used to test the secretion of neurotrophic factors.

RESULTS

The hBMSC-dSCs exhibited bi-/tri-polar morphology of SCs and maintained the expression of the SC markers S100, p75NTR, p0, GFAP, and Sox10, even after withdrawing the glia-inducing factors or hiPSC-dSNs. Electronic microscopy and RNA-seq analysis provided evidence that hBMSC-dSCs were similar to the original human SCs in terms of their function and a variety of characteristics. Furthermore, these cells formed MBP-positive segments and secreted neurotrophic factors to facilitate the neurite outgrowth of Neuro2A.

CONCLUSIONS

These results demonstrated that phenotypically stable and functionally mature hBMSC-dSCs were generated efficiently via the co-culture of hiPSC-dSNs and hBMSC-derived SCLCs. Our findings may provide a promising protocol through which stable and fully developed hBMSC-dSCs can be used for transplantation to regenerate myelin sheath.

Brain inflammation and cognitive decline induced by spinal cord injury can be reversed by spinal cord cell transplants

Spinal cord injuries (SCIs) impact between 250,000 and 500,000 people worldwide annually, often resulting from road accidents or falls. These injuries frequently lead to lasting disabilities, with the severity depending on the injury's extent and location. Emerging research also links SCIs to cognitive impairments due to brain inflammation. From a treatment perspective, various approaches, including cell therapy, have been investigated. One common mechanism across cellular transplant models is the modulation of inflammation at the injury site, though it remains uncertain if these effects extend to the brain. To explore this, we induced SCI in wild-type mice and treated them with either olfactory ensheathing cells or mesenchymal stem cells. Our findings reveal that both cell types can reverse SCI-induced cognitive deficits, reduce brain inflammation, and increase hippocampal neuronal density. This study is the first, to our knowledge, to demonstrate that cells transplanted into the spinal cord can influence brain inflammation and mitigate injury-induced effects on brain functions. These results highlight the intricate relationship between the spinal cord and brain in both health and disease.

Reawakening inflammation in the chronically injured spinal cord using lipopolysaccharide induces diverse microglial states

BACKGROUND

Rehabilitative training is an effective method to promote recovery following spinal cord injury (SCI), with lower training efficacy observed in the chronic stage. The increased training efficacy during the subacute period is associated with a shift towards a more adaptive or proreparative state induced by the SCI. A potential link is SCI-induced inflammation, which is elevated in the subacute period, and, as injection of lipopolysaccharide (LPS) alongside training improves recovery in chronic SCI, suggesting LPS could reopen a window of plasticity late after injury. Microglia may play a role in LPS-mediated plasticity as they react to LPS and are implicated in facilitating recovery following SCI. However, it is unknown how microglia change in response to LPS following SCI to promote neuroplasticity.

MAIN BODY

Here we used single-cell RNA sequencing to examine microglial responses in subacute and chronic SCI with and without an LPS injection. We show that subacute SCI is characterized by a disease-associated microglial (DAM) signature, while chronic SCI is highly heterogeneous, with both injury-induced and homeostatic states. DAM states exhibit predicted metabolic pathway activity and neuronal interactions that are associated with potential mediators of plasticity. With LPS injection, microglia shifted away from the homeostatic signature to a primed, translation-associated state and increased DAM in degenerated tracts caudal to the injury.

CONCLUSION

Microglial states following an inflammatory stimulus in chronic injury incompletely recapitulate the subacute injury environment, showing both overlapping and distinct microglial signatures across time and with LPS injection. Our results contribute to an understanding of how microglia and LPS-induced neuroinflammation contribute to plasticity following SCI.

Local delivery of mesenchymal stem cell-extruded nanovesicles through a bio-responsive scaffold for acute spinal cord injury treatment

Intense inflammatory responses and elevated levels of reactive oxygen species (ROS) extremely exacerbate the pathological process of spinal cord injury (SCI). Mesenchymal stem cell (MSC)-derived extracellular vesicles (EV) can mitigate SCI-related inflammation but their production yield remains limited. Alternatively, MSC-extruded nanovesicles (NV) inherit the therapeutic potential from MSCs and have a markedly higher yield than EV. In the present study, a bio-responsive scaffold system (RS+NV) was created for SCI treatment. NV was generated from human MSCs by physical extrusion and encapsulated in a ROS-responsive scaffold (RS). RS+NV efficiently scavenged environmental ROS and underwent degradation, thus facilitating the responsive release of NV. NV inhibited the pro-inflammatory phenotypic transformation, and reduced the secretion of TNF-α and IL-6 from lipopolysaccharide-stimulated BV2 cells, exhibiting comparable anti-inflammatory properties to EV. Additionally, NV posed a superior antioxidative effect than EV and could effectively alleviate the oxidative stress damage of H2O2-stimulated PC12 cells. Furthermore, in SCI rats, the uptake of NV was primarily attributed to microglia and neurons. RS+NV exhibited synergistic effects in regulating the hostile microenvironment in vivo during the acute phase, thereby establishing a conducive environment for long-term locomotor, tissue repair, and recovery of neuropathic pain. Overall, RS+NV shows promising potential for use as an anti-inflammatory and antioxidative therapeutic approach for treating SCI.

Bibliometric Analysis of Research on Spinal Cord Injury and Mesenchymal Stem Cell: Trends and Frontiers

BACKGROUND

Spinal cord injury (SCI) is a serious neurotraumatic condition leading to motor and sensory dysfunction. Despite advancements in treatment, a complete cure remains elusive. Mesenchymal stem cell (MSC) transplantation has become a popular research area for SCI repair, with numerous publications. However, the current research status and trends are unclear. This study aims to conduct a bibliometric analysis of MSC therapy for SCI to identify these trends.

METHODS

Articles related to MSC therapy for SCI were searched in the Web of Science Core Collection. Data on publication year, country, journal, key words, and citation frequency were analyzed using Bibliometrix and CiteSpace.

RESULTS

A total of 1765 articles were retrieved, showing an increasing trend in publications. Neural Regeneration Research had the most and fastest-growing number of publications, with 59 articles. Kocsis JD was the most prolific author with 23 articles. China led with 775 publications. However, more collaboration among authors, institutions, and countries is needed. Current research focuses on cell differentiation, axon regeneration, and exosome extraction.

CONCLUSIONS

This study offers a comprehensive overview of the current state and future directions of MSC therapy research for SCI, providing a foundation for further research and clinical applications.

Bioinformatics analysis reveals key mechanisms of oligodendrocytes and oligodendrocyte precursor cells regulation in spinal cord Injury

Despite extensive research, spinal cord injuries (SCI), which could cause severe sensory, motor and autonomic dysfunction, remain largely incurable. Oligodendrocytes and oligodendrocyte precursor cells (ODC/OPC) play a crucial role in neural morphological repair and functional recovery following SCI. We performed single-cell sequencing (scRNA-seq) on 59,558 cells from 39 mouse samples, combined with microarray data from 164 SCI samples and 3 uninjured samples. We further validated our findings using a large clinical cohort consisting of 38 SCI patients, 10 healthy controls, and 10 trauma controls, assessed with the American Spinal Cord Injury Association (ASIA) scale. We proposed a novel SCI classification model based on the expression of prognostic differentially expressed ODC/OPC differentiation-related genes (PDEODGs). This model includes three types: Low ODC/OPC Score Classification (LOSC), Median ODC/OPC Score Classification (MOSC), and High ODC/OPC Score Classification (HOSC). Considering the relationship between these subtypes and prognosis, we speculated that enhancing ODC/OPC differentiation and inhibiting inflammatory infiltration may improve outcomes. Additionally, we identified potential treatments for SCI that target key genes within these subtypes, offering promising implications for therapy.

Shared Lineage, Distinct Outcomes: Yap and Taz Loss Differentially Impact Schwann and Olfactory Ensheathing Cell Development Without Disrupting GnRH-1 Migration

Olfactory Ensheathing Cells (OECs) are glial cells originating from the neural crest, critical for bundling olfactory axons to the brain. Their development is crucial for the migration of Gonadotropin-Releasing Hormone-1 (GnRH-1) neurons, which are essential for puberty and fertility. OECs have garnered interest as potential therapeutic targets for central nervous system lesions, although their development is not fully understood. Our single-cell RNA sequencing of mouse embryonic nasal tissues suggests that OECs and Schwann cells share a common origin from Schwann cell precursors yet exhibit significant genetic differences. The transcription factors Yap and Taz have previously been shown to play a crucial role in Schwann cell development. We used Sox10 -Cre mice to conditionally ablate Yap and Taz in migrating the neural crest and its derivatives. Our analyses showed reduced Sox10+ glial cells along nerves in the nasal region, altered gene expression of SCs, melanocytes, and OECs, and a significant reduction in olfactory sensory neurons and vascularization in the vomeronasal organ. However, despite these changes, GnRH-1 neuronal migration remained unaffected. Our findings highlight the importance of the Hippo pathway in OEC development and how changes in cranial neural crest derivatives indirectly impact the development of olfactory epithelia.

Metabolic Reprogramming of Neural Stem Cells by Chiral Nanofiber for Spinal Cord Injury

Exogenous neural stem cells (NSCs) have great potential to reconstitute damage spinal neural circuitry. However, regulating the metabolic reprogramming of NSCs for reliable nerve regeneration has been challenging. This report discusses the biomimetic dextral hydrogel (DH) with right-handed nanofibers that specifically reprograms the lipid metabolism of NSCs, promoting their neural differentiation and rapid regeneration of damaged axons. The underlying mechanism is the intrinsic stereoselectivity between DH and fatty acid-binding protein 5 (FABP5), which facilitates the transportation of fatty acids bound to FABP5 into the mitochondria and endoplasmic reticulum, subsequently augmenting fatty acid oxidation (FAO) levels and enriching sphingosine biosynthesis. In the rat SCI model, DH significantly improved the Basso-Beattie-Bresnahan (BBB) locomotor scores (over 3-fold) and the hindlimbs' compound muscle action potential (over 4-fold) compared with the untreated group, conveying a significant return of functional recovery. This finding of nanoscale chirality-dependent NSCs metabolic reprogramming provides insights into understanding stem cell physiology and presents opportunities for regenerative medicine.

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.

Stem cell-derived exosome treatment for acute spinal cord injury: a systematic review and meta-analysis based on preclinical evidence

Background

The study aims were to systematically review and analyze preclinical research on the efficacy of exosomes derived from various mesenchymal stem cell sources (MSC-exos) for the treatment of spinal cord contusion injury (SCI) in small animal models.

Methods

We conducted a systematic search of PubMed, Embase and Google Scholar databases from their inception through February 29, 2024, to identify eligible English-language studies based on predefined inclusion and exclusion criteria. Two independent investigators performed literature screening, data extraction and bias assessment.

Results

A total of 235 rats were used to assess locomotor recovery at the initial assessment, and exhibited significant improvement in hind limb movement in those treated with exosomes, as indicated by a statistically significant increase in Basso-Beattie-Bresnahan (BBB) scores (MD: 1.26, 95% CI: 1.14-1.38, p < 0.01) compared to the controls. This trend persisted in final assessment data across 21 studies, with pooled analysis confirming similar results (MD: 1.56, 95% CI: 1.43-1.68, p < 0.01). Funnel plot analysis indicated asymmetry in the pooled BBB scores at both baseline and endpoint assessments, suggesting potential publication bias. Exosomes were derived from bone marrow, adipose tissue, umbilical cord or human placental MSCs. Meta-analysis results showed no statistically significant differences in therapeutic efficacy among these MSC-exos sources at various treatment time points.

Conclusion

MSC-exos demonstrated considerable promise in improving motor function in SCI-affected rats, with bone marrow MSC-derived exosomes having particularly notable effectiveness.

Nitric Oxide-Releasing Mesoporous Hollow Cerium Oxide Nanozyme-Based Hydrogel Synergizes with Neural Stem Cell for Spinal Cord Injury Repair

Neural stem cell (NSCs) transplantation is a promising therapeutic strategy for spinal cord injury (SCI), but its efficacy is greatly limited by the local inhibitory microenvironment. In this study, based on l-arginine (l-Arg)-loaded mesoporous hollow cerium oxide (AhCeO2) nanospheres, we constructed an injectable composite hydrogel (AhCeO2-Gel) with microenvironment modulation capability. AhCeO2-Gel protected NSCs from oxidative damage by eliminating excess reactive oxygen species while continuously delivering Nitric Oxide to the lesion of SCI in a pathological microenvironment, the latter of which effectively promoted the neural differentiation of NSCs. The process was confirmed to be closely related to the up-regulation of the cAMP-PKA pathway after NO-induced calcium ion influx. In addition, AhCeO2-Gel significantly promoted the polarization of microglia toward the M2 subtype as well as enhanced the regeneration of spinal nerves and myelinated axons. The prepared bioactive hydrogel system also efficiently facilitated the integration of transplanted NSCs with host neural circuits, replenished damaged neurons, alleviated neuroinflammation, and inhibited glial scar formation, thus significantly accelerating the recovery of motor function in SCI rats. Therefore, AhCeO2-Gel synergized with NSCs transplantation has great potential as an integrated therapeutic strategy to treat SCI by comprehensively reversing the inhibitory microenvironment.

GFAPβ and GFAPδ Isoforms Expression in Mesenchymal Stem Cells, MSCs Differentiated Towards Schwann-like, and Olfactory Ensheathing Cells

Olfactory ensheathing cells (OECs) and mesenchymal stem cells (MSCs) differentiated towards Schwann-like have plasticity properties. These cells express the Glial fibrillary acidic protein (GFAP), a type of cytoskeletal protein that significantly regulates many cellular functions, including those that promote cellular plasticity needed for regeneration. However, the expression of GFAP isoforms (α, β, and δ) in these cells has not been characterized. We evaluated GFAP isoforms (α, β, and δ) expression by Polymerase Chain Reaction (PCR) assay in three conditions: (1) OECs, (2) cells exposed to OECs-conditioned medium and differentiated to Schwann-like cells (dBM-MSCs), and (3) MSC cell culture from rat bone marrow undifferentiated (uBM-MSCs). First, the characterization phenotyping was verified by morphology and immunocytochemistry, using p75, CD90, and GFAP antibodies. Then, we found the expression of GFAP isoforms (α, β, and δ) in the three conditions; the expression of the GFAPα (10.95%AUC) and GFAPβ (9.17%AUC) isoforms was predominantly in OECs, followed by dBM-MSCs (α: 3.99%AUC, β: 5.66%AUC) and uBM-MSCs (α: 2.47%AUC, β: 2.97%AUC). GFAPδ isoform has a similar expression in the three groups (OEC: 9.21%AUC, dBM-MSCs: 11.10%AUC, uBM-MSCs: 9.21%AUC). These findings suggest that expression of different GFAPδ and GFAPβ isoforms may regulate cellular plasticity properties, potentially contributing to tissue remodeling processes by OECs, dBM-MSCs, and uBM-MSCs.

AI-assisted 3D analysis of grasping and reaching behavior of squirrel monkeys during recovery from cervical spinal cord injury

We have previously demonstrated that machine learning-based video analysis, conducted via DeepLabCut, is more sensitive for detecting subtle deficits in hand grasping behavior than traditional end-point performance assessments. This superiority was observed in a nonhuman primate (NHP) model of cervical spinal cord injury, specifically a dorsal column lesion (DCL). The current study aims to further characterize the kinematic aspects of the deficits in hand reaching, grasping, and retrieving behavior from a 3D perspective following a DCL. Squirrel monkeys were trained to retrieve sugar pellets from eight wells, which were located either on a flat plate or a raised tube with varying well depths. This setup was designed to require coordinated finger movements during the task. Immediately after the DCL, the animals exhibited measurable behavioral deficits. These were characterized by significant increases in grasping speed squared and trial completion time, markedly widened movement trajectories of individual fingers, and abnormalities in inter-finger distance and orientation. Increased task difficulty was associated with more pronounced behavioral deficits. By three months post-DCL, video-based measurements indicated no significant recovery, even though global end-point performance had returned to baseline levels. Our findings demonstrate that deprivation of tactile information results in impaired dexterous hand behavior involving coordinated finger movements, and the impairment is sustained for 20 weeks. This spinal cord injury (SCI) model, along with DeepLapCut analysis, provides a valuable platform for separately evaluating sensory and motor functions and their contributions to dexterous hand behavior and may be used for evaluating therapeutic interventions using more sensitive behavioral outcome readouts.

Challenges in advancing Schwann cell transplantation for spinal cord injury repair

BACKGROUND AIMS

In this article we aimed to provide an expert synthesis of the current status of Schwann cell (SC)therapeutics and potential steps to increase their clinical utility.

METHODS

We provide an expert synthesis based on preclinical, clinical and manufacturing experience.

RESULTS

Schwann cells (SCs) are essential for peripheral nerve regeneration and are of interest in supporting axonal repair after spinal cord injury (SCI). SCs can be isolated and cultivated in tissue culture from adult nerve biopsies or generated from precursors and neural progenitors using specific differentiation protocols leading to expanded quantities. In culture, they undergo dedifferentiation to a state similar to "repair" SCs. The known repertoire of SC functions is increasing beyond axon maintenance, myelination, and axonal regeneration to include immunologic regulation and the release of potentially therapeutic extracellular vesicles. Recently, autologous human SC cultures purified under cGMP conditions have been tested in both nerve repair and subacute and chronic SCI clinical trials. Although the effects of SCs to support nerve regeneration are indisputable, their efficacy for clinical SCI has been limited according to the outcomes examined.

CONCLUSIONS

This review discusses the current limitations of transplanted SCs within the damaged spinal cord environment. Limitations include limited post-transplant cell survival, the inability of SCs to migrate within astrocytic parenchyma, and restricted axonal regeneration out of SC-rich graft regions. We describe steps to amplify the survival and integration of transplanted SCs and to expand the repertoire of uses of SCs, including SC-derived extracellular vesicles. The relative merits of transplanting autologous versus allogeneic SCs and the role that endogenous SCs play in spinal cord repair are described. Finally, we briefly describe the issues requiring solutions to scale up SC manufacturing for commercial use.

ARL11 knockdown alleviates spinal cord injury by inhibiting neuroinflammation and M1 activation of microglia in mice

Spinal cord injury (SCI) is a severe central nervous system injury and microglia are major participants in neuroinflammation after injury. ADP-ribosylation factor-like GTPase 11 (ARL11) is a GTP-binding protein. Whether ARL11 is involved in the SCI progression is unknown. In the impactor-induced moderate SCI mouse model, ARL11 protein and mRNA expression were significantly increased in the injury site. LPS (100 ng/mL) and IFN-γ (20 ng/mL) were incubated with BV2 cells (immortalized mouse microglial cell line) to drive them into an M1-like phenotype. ARL11 up-regulation was also observed in activated microglia in SCI mice and LPS and IFN-γ treated BV2 cells. Basso Mouse Scale scores and inclined plate test revealed that ARL11 deletion promoted motor function recovery in SCI mice. Pathological examination showed ARL11 knockdown reduced spinal cord tissue damage, increased neuron numbers, and inhibited neuronal apoptosis in SCI mice. ARL11 knockdown notably inhibited IL-1β and IL-6 production in vivo and in vitro. Furthermore, ARL11 deletion significantly inhibited iNOS protein and mRNA expression in vivo and in vitro, and COX-2 expression in vivo. Mechanism studies revealed that ARL11 silencing decreased phosphorylated ERK1/2 protein expression. Additionally, ELF1 knockdown significantly inhibited ARL11 protein and mRNA expression in vitro. ELF1 acted as a transcription activator in regulating ARL11 expression by binding to the promoter. In conclusion, ARL11 knockdown protects neurons by inhibiting M1 microglia-induced neuroinflammation, thereby promoting motor functional recovery in SCI mice. This may occur in part under the regulation of ELF1. Our study provides a new molecular 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.

Silk-based biomaterials for promoting spinal cord regeneration: A review

The management of neurological disorders is profoundly complicated by spinal cord injury (SCI), which leads to the impairment of motor and sensory functions. A major challenge in the treatment of SCI is the formation of a dysfunctional pathological microenvironment characterized by an excessive inflammatory response, deposition of inhibitory molecules, glial scarring, and vascular dysfunction. A thorough understanding of the pathological and physiological changes following SCI is essential to elucidate the mechanisms underlying functional recovery and to develop effective therapeutic interventions. Recent research indicates that the adverse microenvironment associated with SCI can be modified through the implantation of functional biomaterials at the injury site, thereby facilitating axonal regeneration, myelin repair, and functional recovery. Silk fibroin, in particular, has demonstrated remarkable efficacy in SCI reconstruction due to its superior biocompatibility, biodegradability, and tunable mechanical properties. This review provides an overview of the pathological microenvironmental dysfunctions following SCI and explores the potential advantages of silk fibroin in enhancing axonal regeneration and neural circuit formation in SCI repair. The benefits and challenges associated with silk fibroin and its derivatives in facilitating effective SCI repair are examined. This review aims to offer significant insights into the application of silk-based biomaterials for SCI treatment.

Self-Healing COCu-Tac Hydrogel Enhances iNSCs Transplantation for Spinal Cord Injury by Promoting Mitophagy via the FKBP52/AKT Pathway

In the realm of neural regeneration post-spinal cord injury, hydrogel scaffolds carrying induced neural stem cells (iNSCs) have demonstrated significant potential. However, challenges such as graft rejection and dysfunction caused by mitochondrial damage persist after transplantation, presenting formidable barriers. Tacrolimus, known for its dual role as an immunosuppressant and promoter of neural regeneration, holds the potential for enhancing iNSC transplantation. However, systemic administration of tacrolimus often comes with severe side effects. This study pioneers the development of a self-healing hydrogel with sustained-release tacrolimus (COCu-Tac), tailored specifically for iNSC transplantation after spinal cord injury. This research reveals that the sustained release of tacrolimus enhances axonal growth and improves mitochondrial quality control in iNSCs and neurons. Further analysis shows that tacrolimus targets FKBP52 rather than FKBP51, enhancing mitophagy via the FKBP52/AKT pathway. This advanced system demonstrates significant efficacy in promoting neural regeneration and restoring motor function following spinal cord injury.

Secretome of the Olfactory Ensheathing Cells Influences the Behavior of Neural Stem Cells

Olfactory ensheathing cell (OEC) transplantation demonstrates promising therapeutic results in neurological disorders, such as spinal cord injury. The emerging cell-free secretome therapy compensates for the limitations of cell transplantation, such as low cell survival rates. However, the therapeutic benefits of the human OEC secretome remain unclear. We harvested the secretome from human mucosal OECs and characterized its protein content, identifying 709 proteins in the human OEC secretome from three donors in two passages. Thirty-nine proteins, including neurological-related proteins, such as profilin-1, and antioxidants, such as peroxiredoxin-1 and glutathione S-transferase, were shared between the six samples. The secretome consistently demonstrated potential effects such as antioxidant activity, neuronal differentiation, and quiescence exit of neural stem cells (NSCs). The total secretome produced by OECs protects NSCs from H2O2-induced reactive oxygen species accumulation. During induction of neuronal differentiation, secretomes promoted neurite outgrowth, axon elongation, and expression of neuronal markers. The secretome ameliorated bone morphogenetic protein 4- and fibroblast growth factor 2-induced quiescence of NSCs. The human OEC secretome triggers NSCs to exit prime quiescence, which is related to increased phosphoribosomal protein S6 expression and RNA synthesis. The human OEC secretome has beneficial effects on NSCs and may be applied in neurological disease studies.

Characterization of Mesenchymal and Neural Stem Cells Response to Bipolar Microsecond Electric Pulses Stimulation

In the tissue regeneration field, stem cell transplantation represents a promising therapeutic strategy. To favor their implantation, proliferation and differentiation need to be controlled. Several studies have demonstrated that stem cell fate can be controlled by applying continuous electric field stimulation. This study aims to characterize the effect of a specific microsecond electric pulse stimulation (bipolar pulses of 100 µs + 100 µs, delivered for 30 min at an intensity of 250 V/cm) to induce an increase in cell proliferation on mesenchymal stem cells (MSCs) and induced neural stem cells (iNSCs). The effect was evaluated in terms of (i) cell counting, (ii) cell cycle, (iii) gene expression, and (iv) apoptosis. The results show that 24 h after the stimulation, cell proliferation, cell cycle, and apoptosis are not affected, but variation in the expression of specific genes involved in these processes is observed. These results led us to investigate cell proliferation until 72 h from the stimulation, observing an increase in the iNSCs number at this time point. The main outcome of this study is that the microsecond electric pulses can modulate stem cell proliferation.

Advances in genetically modified neural stem cell therapy for central nervous system injury and neurological diseases

Neural stem cells (NSCs) have increasingly been recognized as the most promising candidates for cell-based therapies for the central nervous system (CNS) injuries, primarily due to their pluripotent differentiation capabilities, as well as their remarkable secretory and homing properties. In recent years, extensive research efforts have been initiated to explore the therapeutic potential of NSC transplantation for CNS injuries, yielding significant advancements. Nevertheless, owing to the formation of adverse microenvironment at post-injury leading to suboptimal survival, differentiation, and integration within the host neural network of transplanted NSCs, NSC-based transplantation therapies often fall short of achieving optimal therapeutic outcomes. To address this challenge, genetic modification has been developed an attractive strategy to improve the outcomes of NSC therapies. This is mainly attributed to its potential to not only enhance the differentiation capacity of NSCs but also to boost a range of biological activities, such as the secretion of bioactive factors, anti-inflammatory effects, anti-apoptotic properties, immunomodulation, antioxidative functions, and angiogenesis. Furthermore, genetic modification empowers NSCs to play a more robust neuroprotective role in the context of nerve injury. In this review, we will provide an overview of recent advances in the roles and mechanisms of NSCs genetically modified with various therapeutic genes in the treatment of neural injuries and neural disorders. Also, an update on current technical parameters suitable for NSC transplantation and functional recovery in clinical studies are summarized.

Co-culturing neural and bone mesenchymal stem cells in photosensitive hydrogel enhances spinal cord injury repair

In mammalian species, neural tissues cannot regenerate following severe spinal cord injury (SCI), for which stem cell transplantation is a promising treatment. Neural stem cells (NSCs) have the potential to repair SCI; however, in unfavourable microenvironments, transplanted NSCs mainly differentiate into astrocytes rather than neurons. In contrast, bone mesenchymal stem cells (BMSCs) promote the differentiation of NSCs into neurons and regulate inflammatory responses. Owing to their easily controllable mechanical properties and similarities to neural tissue, gelatin methacrylate (GelMA) hydrogels offer remarkable cell biocompatibility and regulate the differentiation of NSCs. Therefore, in this study, we propose co-culturing NSCs and BMSCs within low-modulus GelMA hydrogel scaffolds to promote regeneration following SCI. In vitro comparisons revealed that the viability, proliferation, migration, and neuron differentiation capacity of cells in these low-modulus scaffolds exhibit substantially superior performance compared to those in high-modulus hydrogel scaffolds. To the best of our knowledge, this study is the first to report that NSCs/BMSCs co-culture implants can remarkably enhance motor function recovery in SCI rats, reduce the area of spinal cord cavities, stimulate neuron regeneration, and suppress scar tissue formation. Thus, this hydrogel system loaded with co-cultured cells represents a promising therapeutic approach for SCI repair.

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.

Identifying signature genes and their associations with immune cell infiltration in spinal cord injury

Background

Early detection of spinal cord injury (SCI) is conducive to improving patient outcomes. In addition, many studies have revealed the role of immune cells in the progression or treatment of SCI. The objective of this study was to identify the early signature genes and clarify how they are related to immune cell infiltration in SCI.

Methods

We analysed and identified early signature genes associated with SCI via bioinformatics analysis of the GSE151371 dataset from the GEO database. These genes were subsequently verified in the GSE33886 dataset and qRT-PCR. Finally, the CIBERSORT algorithm was used to examine the immune cell infiltration in SCI and its relationship with signature genes.

Results

Seven SCI-related signature genes, including ARG1, RETN, BPI, GGH, CCNB1, HIST1H2AC, and HIST1H2BJ, were identified, and their expression was verified via an external validation cohort and qRT-PCR. Moreover, the ROC curves revealed the diagnostic value of these genes. In addition, on the basis of immune cell infiltration analysis, plasma cells, M0 macrophages, activated CD4+ memory T cells, γδ T cells, naive CD4+ T cells, and resting CD4+ memory T cells may participate in the progression of SCI.

Conclusion

This study identified seven early signature genes of SCI that may serve as biomarkers for the early diagnosis of SCI and contribute to our understanding of immune changes during the pathology of SCI.

Resveratrol Enhances the Efficacy of Combined BM-MSCs Therapy for Rat Spinal Cord Injury via Modulation of the Sirt-1/NF-κB Signaling Pathway

Spinal cord injury (SCI) represents a severe trauma to the central nervous system, resulting in significant disability and imposing heavy burdens on families and society. Pathophysiological changes following SCI often trigger secondary injuries that complicate treatment. Bone marrow mesenchymal stem cells (BM-MSCs) have become a focal point of research due to their multifunctionality and self-renewal capabilities; however, their survival and neuroprotective functions are compromised in inflammatory environments. Resveratrol, known for its anti-inflammatory, anti-aging, and anti-oxidative stress properties, has been extensively studied. This research focuses on the anti-inflammatory effects of resveratrol post-SCI and its combined application with BM-MSCs to treat rat spinal cord injuries, exploring both efficacy and mechanisms. In vivo experiments investigated changes in the Sirt-1 signaling pathway post-SCI, while in vitro studies examined the effects of resveratrol on BM-MSCs under inflammatory conditions. The assessment included recovery of motor function, neuronal survival, and apoptosis in SCI rats treated with resveratrol alone or in combination with BM-MSCs. Findings reveal a correlation between Sirt-1 and inflammation signaling pathways post-injury. Resveratrol significantly enhanced the survival and efficacy of BM-MSCs in inflammatory environments by upregulating Sirt-1 and downregulating NF-κB and other inflammatory markers, thereby reducing apoptosis. Combined treatment with resveratrol and BM-MSCs showed superior outcomes in motor function recovery and neuronal survival compared to treatment with BM-MSCs alone. This study offers a novel therapeutic strategy for SCI, enhancing stem cell survival and function through modulation of the Sirt-1/NF-κB pathway, providing a theoretical and experimental foundation for clinical applications.

Application of olfactory ensheathing cells in peripheral nerve injury and its complication with pathological pain

Direct or indirect injury of peripheral nerve can lead to sensory and motor dysfunction, which can lead to pathological pain and seriously affect the quality of life and psychosomatic health of patients. While the internal repair function of the body after peripheral nerve injury is limited. Nerve regeneration is the key factor hindering the recovery of nerve function. At present, there is no effective treatment. Therefore, more and more attention have been paid to the development of foreground treatment to achieve functional recovery after peripheral nerve injury, including relief of pathological pain. Cell transplantation strategy is a therapeutic method with development potential in recent years, which can exert endogenous alternative repair by transplanting exogenous functional bioactive cells to the site of nerve injury. Olfactory ensheathing cells (OECs) are a special kind of glial cells, which have the characteristics of continuous renewal and survival. The mechanisms of promoting nerve regeneration and functional repair and relieving pathological pain by transplantation of OECs to peripheral nerve injury include secretion of a variety of neurotrophic factors, axonal regeneration and myelination, immune regulation, anti-inflammation, neuroprotection, promotion of vascular growth and improvement of inflammatory microenvironment around nerve injury. Different studies have shown that OECs combined with biomaterials have made some progress in the treatment of peripheral nerve injury and pathological pain. These biomaterials enhance the therapeutic effect of OECs. Therefore, the functional role of OECs in peripheral nerve injury and pathological pain was discussed in this paper.Although OECs are in the primary stage of exploration in the repair of peripheral nerve injury and the application of pain, but OECs transplantation may become a prospective therapeutic strategy for the treatment of peripheral nerve injury and pathological pain.

Adipose-derived stem cell transplantation enhances spinal cord regeneration by upregulating PGRN expression

This study aims to investigate the effect of adipose-derived stem cells (ADSCs) transplantation on progranulin (PGRN) expression and functional recovery in rats with spinal cord injury (SCI). ADSCs were isolated from the inguinal adipose tissue of rats. A SCI model was created, and ADSCs were injected into the injured area. Various techniques were used to assess the effects of ADSCs transplantation, including hematoxylin-eosin staining, Masson staining, immunofluorescence staining, electron microscopy, MRI, and motor function assessment. The potential mechanisms of ADSC transplantation were investigated using gene expression analysis and protein analysis. Finally, the safety of this therapy was evaluated through hematoxylin-eosin staining and indicators of liver and kidney damage in serum. PGRN expression increased in the injured spinal cord, and ADSCs transplantation further enhanced PGRN levels. The group that received ADSCs transplantation showed reduced inflammation, decreased scar formation, increased nerve regeneration, and faster recovery of bladder function. Importantly, motor function significantly improved in the ADSC transplantation group. ADSCs transplantation enhances functional regeneration in SCI by upregulating PGRN expression, reducing inflammation and scar formation, and promoting nerve regeneration and myelin repair. These findings suggest that ADSC transplantation is a potential therapy for SCI.