Fig. 3From: Combined transplantation of mesenchymal stem cells and endothelial progenitor cells for tissue engineering: a systematic review and meta-analysisFunnel plot of vessel density. Dotted line shows the overall estimated standard mean difference. No obvious evidence for publication bias was found. SE standard error, SMD standard mean difference, EPC endothelial progenitor cell, MSC mesenchymal stem cellBack to article page