20 years of treating ischemic cardiomyopathy with mesenchymal stromal cells: a meta-analysis and systematic review

This meta-analysis and systematic review compiles comparative data from 2004 to 2024, investigating the safety and efficacy of mesenchymal stem/stromal cells (MSCs) derived from various tissues for the treatment of ischemic cardiomyopathy (ICM) and associated heart failure. In addition, this review highlights the limitations of these interventions and provides valuable insights for future therapeutic approaches. Relevant articles were retrieved from the PubMed® database using targeted keywords. Our inclusion criteria included clinical trials with patients over 18 years of age, case reports and pilot studies. Animal experiments, in vitro studies, correlational and longitudinal studies, and study designs and protocols were excluded. Forty-nine original articles resulted in follow-up reports of 45 trials. MSCs from bone marrow, umbilical cord and adipose tissue were moderately well tolerated. Of the 1408 participants who received MSCs, 33 trials (67.3%) reported the occurrence of death or serious adverse events. These events resulted in 80 deaths (52% of reported cases) following MSC administration. Importantly, 41.3% of these deaths (n=33) were not considered to be related to the intervention itself, while 40% of these deaths had no reported cause. As the primary outcome, the mean increase in left ventricular ejection fraction (LVEF) from baseline was 5.75% (95% CI: 3.38% to 8.11%, p<0.0001, I2=90,9%) in the randomized controlled trials only (n=24) within the treatment groups and 3.19% (95% CI: 1.63% to 4.75%, p<0.0001, I2=74,17%) in the control groups after the intervention. When the above results were compared using the standardized mean difference (SDM), a significance in favor of the treatment group was also found (SDM=0.41; 95% CI: 0.19 to 0.64, p<0.001, I2=71%). Although improvements were also seen in the control groups, 33.3% (n=15) of the studies showed no significant difference between the control and treatment groups. The six-minute walking test (6MWT) and New York Heart Association (NYHA) class scores, used for assessing exercise tolerance and quality of life (QoL), respectively, further supported the improvements in the treatment group. These improvements were noted as 62.5% (n=10) for the 6MWT and 54.5% (n=12) for the NYHA class scores. According to the risk of bias analysis, four trials were of good quality (11.8%), fifteen were of fair quality (44.1%), and fifteen were of poor quality (44.1%). Major limitations of these studies included small sample size, diagnostic challenges/lack, uncertain cell dosage and potential bias in patient selection. Despite the ongoing debate surrounding cell administration for ICM, there are supporting signs of improved clinical and laboratory outcomes, as well as improved QoL in the MSC-treated groups. However, it is important to recognize the limitations of each study, highlighting the need for larger, controlled trials to validate these findings.