Meta-analysis of the safety and efficacy of stem cell therapies for ischemic stroke in preclinical and clinical studies.

Recent studies have indicated that stem cell transplantation may be effective in the treatment of ischemic stroke. Therefore, we performed a meta-analysis to evaluate the safety and efficacy of stem cell therapy for ischemic stroke in preclinical and clinical studies. In accordance with PRISMA guidelines, we searched the PubMed, Cochrane Library, Embase, Web of science, and Ovid databases from inception through May 2018. A total of 11 preclinical studies--18 independent interventions-were ultimately included. Similarly, 11 clinical studies were finally included. Two authors independently screened trials. Lesion volume and modified neurological severity scores (mNSS) were regarded as outcome measures for preclinical studies. The composite weighted mean (95% CI) effect sizes for lesion volume, percentage of lesion volume, and mNSS were -46.59 [-62.04, -31.15] (P<0.001), -13.18 [-25.62, -0.73] (P=0.04), and -1.85 [-2.17, -1.53] (P<0.001), respectively. Our analysis revealed that all three outcomes were significantly more favorable in the stem cell group than in the control group. Barthel index (BI) values, modified Rankin Scale (mRS) scores, National Institutes of Health Stroke Scale (NIHSS) scores, and Fugl-Meyer Assessment (FMA) scores were regarded as outcome measures for human studies. Our results were as follows: NIHSS [MD=-2.57, 95% CI (-3.45,-1.68), I²=51%, P<0.001]; BI [MD=7.93, 95% CI (3.11,12.75), I²=59%, P=0.001]; mRS [MD=-0.53, 95% CI (-0.73,-0.28), I²=0%, P<0.001]; FMA [MD=5.50, 95% CI (2.05,8.95), I²=15%, P=0.002]. These results suggest that stem cell transplantation was associated with significantly better outcomes than control treatment. Adverse reactions such as mild headache and fever resolved shortly following treatment. Stem cell transplantation can significantly improve neurological deficits and quality of life in patients with ischemic stroke, without severe adverse reactions. Our results also suggest that such treatment is most effective when provided earlier and via the intravenous route.