Stem Cell Therapy for Diabetic Erectile Dysfunction in Rats: A Meta-Analysis

INTRODUCTION: Stem cell therapy is a novel method for the treatment of diabetic erectile dysfunction (ED). Many relative animal studies have been done to evaluate the efficacy of this therapy in rats. AIMS: This meta-analysis was performed to compare the efficacy of different stem cell therapies, to evaluate the influential factors and to determine the optimal stem cell therapeutic strategy for diabetic ED. METHODS: We searched the studies analyzing the efficacy of stem cell therapy for diabetic ED in rats published before September 30, 2015 in PubMed, Web of Science and EBSCO. A random effects meta-analysis was conducted to assess the outcomes of stem cell therapy. Subgroup analysis was also performed by separating these studies based on their different characteristics. Changes in the ratio of intracavernous pressure (ICP) to mean arterial pressure (MAP) and in the structure of the cavernous body were compared. RESULTS: 10 studies with 302 rats were enrolled in this meta-analysis. Pooled analysis of these studies showed a beneficial effect of stem cell therapy in improving erectile function of diabetic rats (SMD 4.03, 95% CI = 3.22 to 4.84, P< 0.001). In the stem cell therapy group, both the smooth muscle and endothelium content were much more than those in control group. There was also significant increase in the expression of endothelial nitric oxide synthase (eNOS) and neuronal nitric oxide synthase (nNOS), the ratio of smooth muscle to collagen, as well as the secretion of vascular endothelial growth factor (VEGF). Besides, apoptotic cells were reduced by stem cell treatment. The subgroup analysis indicated that modified stem cells were more effective than those without modification. CONCLUSIONS: Our results confirmed that stem cell therapy could apparently improve the erectile function of diabetic rats. Some specific modification, especially the gene modification with growth factors, could improve the efficacy of stem cell therapy. Stem cell therapy has potential to be an effective therapeutic strategy for diabetic ED.