Clinical Trials Using Mesenchymal Stem Cells for Spinal Cord Injury: Challenges in Generating Evidence

Adverse events of cell therapy clinical trials in human chronic spinal cord injury, a systematic review and meta-analysis

Spinal cord injury is a lesion with high mortality and significant morbidities. After the primary injury, during six months, a cascade of secondary cellular and molecular events makes the lesion chronic. Recently, cell-based clinical trials as a new procedure have been gradually tested to improve the symptoms of patients. Each treatment method is associated with different adverse events. Based on the PRISMA flow diagram of the identified records, and after multistep screening, finally in 76 reviewed studies with 1633 cases and 189 controls, 64 types of adverse events in 12 categories were recorded in 45 studies. The most common adverse events were transient backache and meningism (90%) and cord malacia (80%). The cell therapy method in which the treatment was associated with more adverse events was Olfactory ensheathing cell and bone marrow mesenchymal stem cell combination therapy in 55%, and the adverse events were less with the embryonic stem cell in 2.33% of patients. In a meta-analysis, the total prevalence of adverse events in cell therapy was 19% and the highest pulled effect size belonged to urinary tract and localized adverse events. Also, the total prevalence of adverse events in 14 cell therapy methods was 18% and four cell types (neural stem cell, bone marrow hematopoietic stem cell, embryonic stem cell, and umbilical cord mesenchymal stem cell) had the most effect. None of the adverse events were reported on the 4 (life-threatening consequences) and 5 (death) grading scales. We concluded that the frequency of life-threatening adverse events following cell therapy clinical trials in chronic spinal cord injury patients is very scarce and can be ignored.

Safety and potential efficacy of expanded mesenchymal stromal cells of bone marrow and umbilical cord origins in patients with chronic spinal cord injuries: a phase I/II study

BACKGROUND AIMS

Spinal cord injury (SCI) affects patients' physical, psychological, and social well-being. Presently, treatment modalities for chronic SCI have restricted clinical effectiveness. Mesenchymal stromal cells (MSCs) demonstrate promise in addressing nervous tissue damage. This single-center, open-label, parallel-group randomized clinical trial aimed to assess the safety and efficacy of intraoperative perilesional administration of expanded autologous bone marrow-derived MSCs (BMMSCs), followed by monthly intrathecal injections, in comparison to monthly intrathecal administration of expanded allogeneic umbilical cord-derived MSCs (UCMSCs) for individuals with chronic SCI.

METHODS

Twenty participants, who had a minimum of 1 year of SCI duration, were enrolled. Each participant in Group A received perilesional BMMSCs, followed by monthly intrathecal BMMSCs for three injections, while Group B received monthly intrathecal UCMSCs for three injections. Safety and efficacy were evaluated using the American Spinal Cord Injury Association (ASIA) score for at least 1 year post the final injection. Statistical analysis was conducted using the Wilcoxon signed-rank test.

RESULTS

Group A comprised 11 participants, while Group B included 9. The mean follow-up duration was 22.65 months. Mild short-term adverse events encompassed headaches and back pain, with no instances of long-term adverse events. Both groups demonstrated significant improvements in total ASIA scores, with Group A displaying more pronounced motor improvements.

CONCLUSIONS

Our findings indicate that perilesional administration of expanded autologous BMMSCs, followed by monthly intrathecal BMMSCs for three injections, or monthly intrathecal UCMSCs for three injections appear to be safe and hold promise for individuals with chronic SCI. Nonetheless, larger-scale clinical trials are imperative to validate these observations.

Stem cell therapies for neurological disorders: current progress, challenges, and future perspectives

Stem cell-based therapies have emerged as a promising approach for treating various neurological disorders by harnessing the regenerative potential of stem cells to restore damaged neural tissue and circuitry. This comprehensive review provides an in-depth analysis of the current state of stem cell applications in primary neurological conditions, including Parkinson's disease (PD), Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), stroke, spinal cord injury (SCI), and other related disorders. The review begins with a detailed introduction to stem cell biology, discussing the types, sources, and mechanisms of action of stem cells in neurological therapies. It then critically examines the preclinical evidence from animal models and early human trials investigating the safety, feasibility, and efficacy of different stem cell types, such as embryonic stem cells (ESCs), mesenchymal stem cells (MSCs), neural stem cells (NSCs), and induced pluripotent stem cells (iPSCs). While ESCs have been studied extensively in preclinical models, clinical trials have primarily focused on adult stem cells such as MSCs and NSCs, as well as iPSCs and their derivatives. We critically assess the current state of research for each cell type, highlighting their potential applications and limitations in different neurological conditions. The review synthesizes key findings from recent, high-quality studies for each neurological condition, discussing cell manufacturing, delivery methods, and therapeutic outcomes. While the potential of stem cells to replace lost neurons and directly reconstruct neural circuits is highlighted, the review emphasizes the critical role of paracrine and immunomodulatory mechanisms in mediating the therapeutic effects of stem cells in most neurological disorders. The article also explores the challenges and limitations associated with translating stem cell therapies into clinical practice, including issues related to cell sourcing, scalability, safety, and regulatory considerations. Furthermore, it discusses future directions and opportunities for advancing stem cell-based treatments, such as gene editing, biomaterials, personalized iPSC-derived therapies, and novel delivery strategies. The review concludes by emphasizing the transformative potential of stem cell therapies in revolutionizing the treatment of neurological disorders while acknowledging the need for rigorous clinical trials, standardized protocols, and multidisciplinary collaboration to realize their full therapeutic promise.

Pericyte derivation and transplantation for blood-CNS barrier reconstitution in CNS disorders

Disruption of the blood-central nervous system barrier (BCB) is increasingly recognized as a pathological factor in diseases and trauma of the central nervous system. Despite the neuropathological impact, current treatment modalities do not target the BCB; strategies to reconstitute the impaired BCB have been restricted to nutritional and dietary remedies. As an integral cell type in the neurovascular unit, pericytes are crucial to the development, maintenance, and repair of the BCB. As such, pericytes are well poised as cellular agents for reconstitution of the impaired BCB. Here, we summarize recent revelations regarding the role of BCB disruption in diseases and trauma of the central nervous system and highlight how pericytes are harnessed to provide targeted therapeutic effect in each case. This review will also address how recent advances in pericyte derivation strategies can serve to overcome practical hurdles in the clinical use of pericytes.

Systematic Review of Cell Therapy Efficacy in Human Chronic Spinal Cord Injury

Spinal cord injury (SCI) is one of the most debilitating problems for humans. About 6 months after the initial injury, a cascade of secondary cellular and molecular events occurs and the primary damage enters the chronic phase. Current treatments are not curative. One of the new treatment methods is the use of cell therapy, which is gradually being tested in clinical trials to improve the symptoms of SCI patients. In this review article, we investigated the effect of different cell therapy trials in improving patients' symptoms and their paraclinical indicators. In the 72 final reviewed studies with 1144 cases and 186 controls, 20 scores were recorded as outcomes. We categorized the scores into seven groups. In upper extremity motor score, daily living function, trunk stability, postural hypotension, somatosensory evoked potential, and motor evoked potential scores, the bone marrow hematopoietic stem cell therapy had a more healing effect. In the International Association of Neurorestoratology SCI Functional Rating Scale, light touch score, bowel function, decreased spasticity, Visual Analog Scale, and electromyography scores, the bone marrow mesenchymal stem cell had more impact. The olfactory ensheathing cell had a greater effect on lower extremity motor score and pinprick scores than other cells. The embryonic stem cell had the greatest effect in improving the important score of the American Spinal Injury Association scale. Based on the obtained results, it seems that a special cell should be used to improve each symptom of patients with chronic SCI, and if the improvement of several harms is involved, the combination of cells may be effective. Impact statement Compared to similar review articles published so far, we reviewed the largest number of published articles, and so the largest number of cases and controls, and the variety of cells we examined was more than other published articles. We concluded that different cells are effective for improving the symptoms and paraclinical indicators of patients with chronic spinal cord injury. Bone marrow hematopoietic stem cell and bone marrow mesenchymal stem cell have had the higher overall mean effect in more scores (each in six scores). If the improvement of several harms is involved, the combination of cells may be effective.

Could conditioned medium be used instead of stem cell transplantation to repair spinal cord injury in animal models? Identifying knowledge gaps

The drawbacks of stem cell (SC) therapies have led to investigations of SC conditioned medium (CM) instead of SC transplantation in the repair of spinal cord injury (SCI). However, the effectiveness of CM in comparison with cell transplantation in SCI models remain an open and intriguing question. The focus of this review was to survey existing publications addressing this comparison. The review included articles from electronic databases Medline, Embase, Scopus, and Web of Science that included comparisons of the effects of CM versus SC transplantation and versus controls on locomotion after SCI. The search yielded 5 studies and 6 experiments. The results indicated that there was insufficient evidence to conclude that treatment with CM and source cells were equally effective (SMD = 0.12; 95% CI = -0.36 to 0.59; p = 0.07). Regarding investigations of separate effects of SCs versus CM, there currently is limited evidence on efficacy in SCI models. This highlights a notable concern affecting this field. Thus, we identified critical knowledge gaps concerning comparisons of the efficacy of therapeutic application of SC and their derived CM on functional recovery following SCI.

Applications of chitosan-based biomaterials: From preparation to spinal cord injury neuroprosthetic treatment

Spinal cord injury (SCI)-related disabilities are a serious problem in the modern society. Further, the treatment of SCI is highly challenging and is urgently required in clinical practice. Research on nerve tissue engineering is an emerging approach for improving the treatment outcomes of SCI. Chitosan (CS) is a cationic polysaccharide derived from natural biomaterials. Chitosan has been found to exhibit excellent biological properties, such as nontoxicity, biocompatibility, biodegradation, and antibacterial activity. Recently, chitosan-based biomaterials have attracted significant attention for SCI repair in nerve tissue engineering applications. These studies revealed that chitosan-based biomaterials have various functions and mechanisms to promote SCI repair, such as promoting neural cell growth, guiding nerve tissue regeneration, delivering nerve growth factors, and as a vector for gene therapy. Chitosan-based biomaterials have proven to have excellent potential for the treatment of SCI. This review aims to introduce the recent advances in chitosan-based biomaterials for SCI treatment and to highlight the prospects for further application.

Study of nerve cell regeneration on nanofibers containing cerium oxide nanoparticles in a spinal cord injury model in rats

Since the CNS is unable to repair itself via neuronal regeneration in adult mammals, alternative therapies need to be found. The use of cerium oxide nanoparticles to repair nerve damage could be a promising approach for spinal cord reconstruction. In this study, we constructed a scaffold containing cerium oxide nanoparticles (Scaffold-CeO₂) and investigated the rate of nerve cell regeneration in a rat model of spinal cord injury. The scaffold of gelatin and polycaprolactone was synthesized, and a gelatin solution containing cerium oxide nanoparticles was attached to the scaffold. For the animal study, 40 male Wistar rats were randomly divided into 4 groups (n = 10): (a) Control; (b) Spinal cord injury (SCI); (c) Scaffold (SCI + scaffold without CeO₂ nanoparticles); (d) Scaffold-CeO₂ (SCI + scaffold containing CeO₂ nanoparticles). After creation of a hemisection SCI, scaffolds were placed at the site of injury in groups c and d, and after 7 weeks the rats were subjected to behavioral tests and then sacrificed for preparation of the spinal cord tissue to measure the expression of G-CSF, Tau and Mag proteins by Western blotting and Iba-1 protein by immunohistochemistry. The result of behavioral tests confirmed motor improvement and pain reduction in the Scaffold-CeO₂ group compared to the SCI group. Decreased expression of Iba-1 and higher expression of Tau and Mag in the Scaffold-CeO₂ group compared to the SCI group could be the result of nerve regeneration caused by the scaffold containing CeONPs as well as relief of pain symptoms.

Efficacy of mesenchymal stromal cells intraspinal transplantation for patients with different degrees of spinal cord injury: A systematic review and meta-analysis

BACKGROUND AIMS

Several studies have reported that mesenchymal stromal cells (MSCs) may improve neurological functions in patients with spinal cord injury (SCI). In this study, we conducted a systematic review and meta-analysis to summarize the effects of MSC treatment on different degrees of severity of SCI.

METHODS

Systematic searching of studies reporting outcomes of MSCs on specific injury severities of patients with SCI was performed in The National Library of Medicine (MEDLINE), Embase and Cochrane for published articles up to the 6 July 2022. Two investigators independently reviewed the included studies and extracted the relevant data. The standardized mean differences of American Spinal Injury Association (ASIA) motor score, ASIA light touch scores, ASIA pinprick scores and the Barthel index between baseline and follow-ups were pooled.

RESULTS

A total of eight studies were included. A large majority focused on patients with ASIA grade A classification. The pooled mean differences of ASIA motor scores, ASIA light touch scores, ASIA pinprick scores and the Barthel index were -2.78 (95% confidence interval [CI] -5.12 to -0.43, P = 0.02), -18.26 (95% CI -26.09 to -10.43, P < 0.01), -17.08 (95% CI -24.10 to -10.07, P < 0.01) and -4.37 (95% CI -10.96 to 2.22, P = 0.19), respectively.

CONCLUSIONS

MSC transplantation was a significantly effective therapy for patients with SCI with ASIA grade A. In the future, further studies are warranted to confirm the potential beneficial effects of MSC therapy.

Molecular Mechanisms and Clinical Application of Multipotent Stem Cells for Spinal Cord Injury

Spinal Cord Injury (SCI) is a common neurological disorder with devastating psychical and psychosocial sequelae. The majority of patients after SCI suffer from permanent disability caused by motor dysfunction, impaired sensation, neuropathic pain, spasticity as well as urinary complications, and a small number of patients experience a complete recovery. Current standard treatment modalities of the SCI aim to prevent secondary injury and provide limited recovery of lost neurological functions. Stem Cell Therapy (SCT) represents an emerging treatment approach using the differentiation, paracrine, and self-renewal capabilities of stem cells to regenerate the injured spinal cord. To date, multipotent stem cells including mesenchymal stem cells (MSCs), neural stem cells (NSCs), and hematopoietic stem cells (HSCs) represent the most investigated types of stem cells for the treatment of SCI in preclinical and clinical studies. The microenvironment of SCI has a significant impact on the survival, proliferation, and differentiation of transplanted stem cells. Therefore, a deep understanding of the pathophysiology of SCI and molecular mechanisms through which stem cells act may help improve the treatment efficacy of SCT and find new therapeutic approaches such as stem-cell-derived exosomes, gene-modified stem cells, scaffolds, and nanomaterials. In this literature review, the pathogenesis of SCI and molecular mechanisms of action of multipotent stem cells including MSCs, NSCs, and HSCs are comprehensively described. Moreover, the clinical efficacy of multipotent stem cells in SCI treatment, an optimal protocol of stem cell administration, and recent therapeutic approaches based on or combined with SCT are also discussed.

Application and prospects of somatic cell reprogramming technology for spinal cord injury treatment

Spinal cord injury (SCI) is a serious neurological trauma that is challenging to treat. After SCI, many neurons in the injured area die due to necrosis or apoptosis, and astrocytes, oligodendrocytes, microglia and other non-neuronal cells become dysfunctional, hindering the repair of the injured spinal cord. Corrective surgery and biological, physical and pharmacological therapies are commonly used treatment modalities for SCI; however, no current therapeutic strategies can achieve complete recovery. Somatic cell reprogramming is a promising technology that has gradually become a feasible therapeutic approach for repairing the injured spinal cord. This revolutionary technology can reprogram fibroblasts, astrocytes, NG2 cells and neural progenitor cells into neurons or oligodendrocytes for spinal cord repair. In this review, we provide an overview of the transcription factors, genes, microRNAs (miRNAs), small molecules and combinations of these factors that can mediate somatic cell reprogramming to repair the injured spinal cord. Although many challenges and questions related to this technique remain, we believe that the beneficial effect of somatic cell reprogramming provides new ideas for achieving functional recovery after SCI and a direction for the development of treatments for SCI.

Intrathecal Cell Therapy with Autologous Bone Marrow Stromal Cells as a New Tool for Neurologic Sequels after Spinal Cord Surgery: A Report of Two Cases

Background aims: The possibility of permanent neurological sequels after surgery of benign lesions affecting the spinal cord is well known. Frequently, they are irreversible, with no effective treatment other than rehabilitation. However, in recent years, intrathecal cell therapy with autologous bone marrow stromal cells (MSCs) in patients with incomplete paraplegia has shown benefits for diverse sequels of spinal cord injury (SCI). Methods: We present two patients with chronic spinal cord sequels after a surgery, who underwent cell therapy treatment with NC1 medicament (repeated intrathecal administrations of MSCs). Results: In both cases, cell therapy achieved a clear improvement in neurological sequels, such as recovery of gait disturbances, bowel dysfunction, or neuropathic pain. Conclusion: Intrathecal cell therapy with autologous MSCs offers a new approach for neurological sequels after spinal cord surgery.

Therapeutic Strategy of Mesenchymal-Stem-Cell-Derived Extracellular Vesicles as Regenerative Medicine

Extracellular vesicles (EVs) are lipid bilayer membrane particles that play critical roles in intracellular communication through EV-encapsulated informative content, including proteins, lipids, and nucleic acids. Mesenchymal stem cells (MSCs) are pluripotent stem cells with self-renewal ability derived from bone marrow, fat, umbilical cord, menstruation blood, pulp, etc., which they use to induce tissue regeneration by their direct recruitment into injured tissues, including the heart, liver, lung, kidney, etc., or secreting factors, such as vascular endothelial growth factor or insulin-like growth factor. Recently, MSC-derived EVs have been shown to have regenerative effects against various diseases, partially due to the post-transcriptional regulation of target genes by miRNAs. Furthermore, EVs have garnered attention as novel drug delivery systems, because they can specially encapsulate various target molecules. In this review, we summarize the regenerative effects and molecular mechanisms of MSC-derived EVs.