The improvements in the expressions of eNOS, α-SMA, HIF-1α and TGF-β in the penis with VED therapy under different negative pressures. Immunohistochemistry was used to show the expression changes in these molecular indicators. The data showed that the expression of molecular indicators, such as (a) eNOS and (b) α-SMA, increased after VED therapy, and (c) HIF-1α and (d) TGF-β decreased (magnification, ×20). No obvious difference was found among different VED therapy groups in most molecular indicators except for TGF-β; the expression of TGF-β in high negative pressure treatment groups (>200 mmHg) displayed an upward tendency, and (e) eNOS, (f) α-SMA, (g) HIF1-α, and (h) TGF-β in turn (Student's t-test was used for each comparison, *P < 0.05, n = 6 per group; scale bars = 50 μm). eNOS: endothelial nitric oxide synthase; α-SMA: alpha smooth muscle action; HIF-1α: hypoxia-inducible factor 1α; TGF-β: transforming growth factor beta; VED: vacuum erection device; BCNC: bilateral cavernous nerve crush.