Extracellular vesicles derived from mesenchymal stromal cells may possess increased therapeutic potential for acute kidney injury compared with conditioned medium in rodent models: A meta-analysis.

The potential involvement of the endocrine/paracrine mechanisms in the mesenchymal stromal cells (MSCs) therapy for acute kidney injury (AKI) has been increasingly studied. The aim of the present meta-analysis was to systematically review the therapeutic role of MSC-conditioned medium (CM) or MSCs released by extracellular vesicles (Evs) for the treatment of AKI in rodent models. Studies were identified using PubMed and Scopus databases using a custom search strategy and eligibility criteria. Data regarding serum creatinine (SCr) concentration, CM or Evs, measurement time point, AKI model (toxic or non-toxic) and other parameters, including delivery route, animal type and animal numbers, were extracted. Pooled analysis and subgroup analysis as well as multivariable meta-regression were performed. Heterogeneity and publication bias were also investigated. A total of 13 studies were included and analyzed. Pooled analysis showed reduced SCr (0.93 [0.67, 1.20], mg/dl) in rodent models of AKI after CM/Evs therapy. The results of the subgroup analysis suggested that Evs induced an increased therapeutic effect, in the form of SCr reduction, as compared with CM (P=0.05). There were also other significant influential factors for SCr reduction including measurement time point (P=0.0004) and therapeutic time point (P<0.0001) after surgery. By contrast, parameters such as delivery route, injury type and cell type were not significant influential factors. Multivariable meta-regression analysis showed that measurement time point (P=0.041), therapeutic time point (P=0.03), Evs or CM (P=0.0003) and cell type (P<0.0001) were influential factors in the reduction of SCr. The present meta-analysis indicates that CM or Evs derived from MSCs are able to improve the impaired renal function in rodents modelling AKI. Compared with CM, Evs may produce a more marked therapeutic effect in recovery from renal failure. In addition, CM or Evs administration in early stages of AKI may result in more evident effects.