Fig. 9
multivariable meta-regression analysis P < 0.05 Considering this variable is the cause of heterogeneity.(var9: extracellular vesicles are primarily derived from stem progenitor cells and non-stem progenitor cells; var10: experimental animals are mainly divided into mice and rats; var11: administration is divided into intratracheal administration and intravenous administration; var12: intervention time is divided into whether the intervention time is more than 48 h or not; var13: different scoring system of the lung injury score is divided into the semi-quantitative grading system and the lung injury scoring system)