A systematic review of preclinical studies on therapeutic potential of mesenchymal stem/stromal cells and their secretome in bacterial infections.

backgroundBacterial infections are a globally growing health issue, with an estimated 7.7 million deaths attributed to these infections worldwide. These life-threatening infections, primarily linked to antimicrobial resistance, are difficult to treat, and the growing reliance on last-resort antibiotics is exacerbating the problem. For this reason, numerous preclinical studies have been conducted using mesenchymal stem/stromal cells (MSCs) and their secretome as an alternative new therapeutic strategy for treating bacterial infections. However, these studies exhibit substantial disparities, often due to the lack of a consensus definition for MSCs and the broad variability in their reported characteristics. Thus, the purpose of this systematic review was to summarize studies that have used various sources of human MSCs and their secretome to treat bacterial infection in rodent models, to present an overview of evidence to proceed with clinical studies.

methodsThis systematic review was registered with PROSPERO and conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Using search terms related to "mesenchymal stem cells", "mesenchymal stromal cells" as recommended by ISCT, "bacterial infections", and "therapy", candidate articles were identified through the PubMed database, and data were gathered using a narrative approach.

resultsOf the 517 articles retrieved, only thirty-seven studies met the inclusion criteria, and their analysis revealed several main findings. Human MSCs demonstrated positive effects mainly in decreasing bacterial load, reducing injuries, and improving the overall survival rate in rodents, with bone marrow-derived MSCs being the most used and effective type. All studies demonstrated that MSCs and their secretome can modify and enhance the immune response in rodents after bacterial infection.

conclusionsThis study showed that employing both stem cell-based and cell-free therapies for the treatment of bacterial infections has significant results in preclinical studies, offering promising potential as alternative treatment options. However, the findings are based solely on rodent models and the absence of donor-related investigations, which significantly limit the translation of results to clinical settings. Additionally, the persisting heterogeneity of MSCs remains a key hurdle, underscoring the necessity for further research before considering clinical implementation.