A Systematic Review of Safety Reporting in Acute Spinal Cord Injury Clinical Trials: Challenges and Recommendations

Current status and future perspectives on stem cell transplantation for spinal cord injury

BACKGROUND

Previous assessments of stem cell therapy for spinal cord injuries (SCI) have encountered challenges and constraints. Current research primarily emphasizes safety in early-phase clinical trials, while systematic reviews prioritize effectiveness, often overlooking safety and translational feasibility. This situation prompts inquiries regarding the readiness for clinical adoption.

AIM

To offer an up-to-date systematic literature review of clinical trial results con cerning stem cell therapy for SCI.

METHODS

A systematic search was conducted across major medical databases [PubMed, Embase, Reference Citation Analysis (RCA), and Cochrane Library] up to October 14, 2023. The search strategy utilized relevant Medical Subject Heading (MeSH) terms and keywords related to "spinal cord", "injury", "clinical trials", "stem cells", "functional outcomes", and "adverse events". Studies included in this review consisted of randomized controlled trials and non-randomized controlled trials reporting on the use of stem cell therapies for the treatment of SCI.

RESULTS

In a comprehensive review of 66 studies on stem cell therapies for SCI, 496 papers were initially identified, with 237 chosen for full-text analysis. Among them, 236 were deemed eligible after excluding 170 for various reasons. These studies encompassed 1086 patients with varying SCI levels, with cervical injuries being the most common (42.2%). Bone marrow stem cells were the predominant stem cell type used (71.1%), with various administration methods. Follow-up durations averaged around 84.4 months. The 32.7% of patients showed functional impro vement from American spinal injury association Impairment Scale (AIS) A to B, 40.8% from AIS A to C, 5.3% from AIS A to D, and 2.1% from AIS B to C. Sensory improvements were observed in 30.9% of patients. A relatively small number of adverse events were recorded, including fever (15.1%), headaches (4.3%), muscle tension (3.1%), and dizziness (2.6%), highlighting the potential for SCI recovery with stem cell therapy.

CONCLUSION

In the realm of SCI treatment, stem cell-based therapies show promise, but clinical trials reveal potential adverse events and limitations, underscoring the need for meticulous optimization of transplantation conditions and parameters, caution against swift clinical implementation, a deeper understanding of SCI pathophysiology, and addressing ethical, tumorigenicity, immunogenicity, and immunotoxicity concerns before gradual and careful adoption in clinical practice.

Clinical translation of stem cell therapy for spinal cord injury still premature: results from a single-arm meta-analysis based on 62 clinical trials

BACKGROUND

How much scientific evidence is there to show that stem cell therapy is sufficient in preclinical and clinical studies of spinal cord injury before it is translated into clinical practice? This is a complicated problem. A single, small-sample clinical trial is difficult to answer, and accurate insights into this question can only be given by systematically evaluating all the existing evidence.

METHODS

The PubMed, Ovid-Embase, Web of Science, and Cochrane databases were searched from inception to February 10, 2022. Two independent reviewers performed the literature search, identified and screened the studies, and performed a quality assessment and data extraction.

RESULTS

In total, 62 studies involving 2439 patients were included in the analysis. Of these, 42 were single-arm studies, and 20 were controlled studies. The meta-analysis showed that stem cells improved the ASIA impairment scale score by at least one grade in 48.9% [40.8%, 56.9%] of patients with spinal cord injury. Moreover, the rate of improvement in urinary and gastrointestinal system function was 42.1% [27.6%, 57.2%] and 52.0% [23.6%, 79.8%], respectively. However, 28 types of adverse effects were observed to occur due to stem cells and transplantation procedures. Of these, neuropathic pain, abnormal feeling, muscle spasms, vomiting, and urinary tract infection were the most common, with an incidence of > 20%. While no serious adverse effects such as tumorigenesis were reported, this could be due to the insufficient follow-up period.

CONCLUSIONS

Overall, the results demonstrated that although the efficacy of stem cell therapy is encouraging, the subsequent adverse effects remain concerning. In addition, the clinical trials had problems such as small sample sizes, poor design, and lack of prospective registration, control, and blinding. Therefore, the current evidence is not sufficiently strong to support the clinical translation of stem cell therapy for spinal cord injury, and several problems remain. Additional well-designed animal experiments and high-quality clinical studies are warranted to address these issues.