| Background and ObjectionErectile dysfunction (ED) has been defined as the persistent inability to attain and maintain an erection sufficient to permit satisfactory sexual performance. ED affects physical and psychological health and has a significant impact on the life quality of sufferers and their partners. ED is one of the major complications of diabetes mellitus (DM). The pathogenesis of diabetic ED is multifactorial and complicated. Today, oral phosphodiesterase-5 inhibitors (PDE5i) are generally considered the first-line choice for ED patients. However, in diabetic men, the efficacy of PDE5i is considerably less than 60 to 70%. For the purpose of exploring more effective therapeutic strategies for restoration of the diabetic cavernous body, regenerative medicine is an inevitable subject. Recently, stem cell transplantation and LESWT have emerged as potentially effective treatment protocols for diabetic ED.BMSCs are among the common stem cells transplanted in diabetic ED rats. These cells could improve erectile function, increase the content of endothelium and smooth muscle and exert anti-fibrotic effects. Upon tracking transplanted stem cells in diabetic ED rat models, the number of visible BMSCs was rather low and decreased rapidly in the subsequent period. Similar results were achieved with adipose-derived mesenchymal stem cell transplantation in diabetic rats and different types stem cell transplantation in rat models of cavernous nerve injury (CNI). The low survival number of intracavernosally injected stem cells limited the therapeutic effects of BMSC transplantation.LESWT can improve the erectile function of diabetic rats by promoting the regeneration of endothelial cells, smooth muscle cells and exerting anti-fibrotic effects. In addition to improving angiogenesis, the mechanism of action of LESWT might be related to the recruitment of endogenetic stem cells. Intraperitoneally injected EdU-labeled mesenchymal stem cells (MSCs) are recruited by LESWT and migrate to the cavernous body.If LESWT can inhibit the migration of intracavernosally injected stem cells leaving the cavernous body and create a beneficial microenvironment for an exogenous stem cell niche to be established in the diabetic cavernous body, the survival of transplanted BMSCs would increase. Naturally, the combination of LESWT and BMSC transplantation should improve the erectile function of diabetic rats more effectively.Methods and materials1. The influence of LESWT on circulating EPC numberTwenty-four health SD rats were induced to be diabetes by streptozotocin intraperitoneally injecteion and randomized into two groups (n=12, each group). The rats from the LESWT group received LESWT treatment three times weekly for two weeks with a one-week interval. Before and at the end of the three-week course of LESWT, peripheral blood samples from the tail veins of the groups receiving LESWT or not were obtained to detect CD31 and CD34 expression levels. The results were expressed as the double positive cell percentage of the total mononuclear cell number.2. The influence of LESWT on tansplanted BMSC survivalBMSC was isolated, cultured and labeled with CM-DiO. Eighteen health SD rats were induced to be diabetes by streptozotocin intraperitoneally injecteion and randomized into two groups (n=9, each group). The rats from the LESWT group received LESWT treatment three times weekly for two weeks with a one-week interval. The rats received BMSC transplantation 1 day after three-week-course of LESWT. At one, three and 28 days after BMSC transplantation, freshly dissected tissues of the cavernous bodies of three rats were harvested to evaluate the numbers of survival transplanted BMSCs.3. The influence of combining LESWT and BMSCtransplantation on eretile function of diabetic rats.Forty-eight diabetic rats were randomized into four groups. The DM group (n=6) was a diabetic control group. In the LESWT group (n=6), the rats received a course of LESWT for three weeks. In the LESWT+BMSC group (n=15), the rats received BMSC transplantation 1 day after three-week-course of LESWT. In the BMSC group (n=15), the rats only received BMSC transplantation at the same time as the LESWT+BMSC group but without LESWT. Another six healthy adult rats that did not receive streptozotocin injections were included as a normal group. Four weeks after BMSC transplantation, intracavernous pressure/mean arterial pressure (ICP/MAP) measurements, reverse transcription polymerase chain reaction (RT-PCR) of stromal cell-derived factor-1 (SDF-1) and vascular endothelial growth factor (VEGF) and penile histological assessment about CD31, endothelial nitric oxide synthase (eNOS), α-smooth muscle actin (a-SMA) and Masson Trichrome staining were performed.Statistical analysisThe outcomes are shown as the means±standard errors. Statistical comparisons among the groups were performed with one-way ANOVA. The unpaired t test was performed between two groups using SPSS software, version 17.0.Results1. The influence of LESWT on circulating EPC number Before LESWT, no difference in the number of circulating CD31/CD34-positive cells was noted between the rats receiving LESWT and those that did not(p=0.515). At the end of the three-week course of LESWT, the number of circulating CD31/CD34-positive cells in the rats that received LESWT was increased compared with the rats that did not receive LESWT (p<0.001).2. The influence of LESWT on tansplanted BMSC survival One day after BMSC transplantation, the numbers of stem cells implanted in the cavernous bodies in both the BMSC group and the LESWT+BMSC group were similar ((p=0.143). Three days after transplantation, in the BMSC group, the stem cells disappeared quickly. However, in the LESWT+BMSC group, most of the stem cells remained in the cavernous body (p<0.001). Four weeks after BMSC transplantation, almost no CM-DiO labeled BMSCs were identified in the cavernous body per field in the BMSC group. In contrast, in the LESWT+BMSC group, the number of CM-DiO labeled BMSCs in the specimens per field were increased approximately 10-fold (p<0.001).3. The influence of combining LESWT and BMSCtransplantation on eretile function of diabetic rats. Four weeks after transplantation, the mean of ICP/MAP in the DM group was rEdUced compared with the normal group (P<0.001). Both LESWT and BMSC transplantation could improve the ICP/MAP ratio(p=0.002, p=0.017), whereas the combination of LSWT and BMSC transplantation improved the ICP/MAP ratio more effectively than LESWT or BMSC transplantation performed alone (p<0.001,p< 0.001). Both LESWT and BMSC transplantation improve SDF-1 (p=0.029; p= 0.005) and VEGF (p=0.021; p=0.004) expression. The combination of LESWT and BMSC transplantation improved SDF-1 (p<0.001, p<0.001) and VEGF (p =0.012, p=0.042) expression more than LESWT or BMSC transplantation alone. Compared with the normal group, a significant decrease in the positively stained area of CD31, eNOS, α-SMA or smooth muscle/collagen ratio was observed in the DM group (p<0.001, p<0.001, p<0.001, p<0.001), suggesting serious cell damage and fibrosis in penile tissue. After diabetic rats were treated by LESWT or BMSC transplantation, CD31-, eNOS-, and a-SMA-positive stained areas and smooth muscle/collagen ratio increased significantly (LESWT:p=0.002, p=0.031. p<0.001, p=0.002; BMSC transplantation:p<0.001, p=0.013, p=0.014, p= 0.002). The combination of LESWT and BMSC transplantation increased CD31 and eNOS expression more effectively than LESWT (p=0.002, p=0.007), increased a-SMA expression more effectively than BMSC transplantation (p=0.022), and increased the smooth muscle/collagen ratio more effectively than LESWT and BMSC transplantation performed alone (p=0.005, p=0.005)ConclusionLESWT could increase SDF-1 levels, which could subsequently inhibit the migration of transplanted BMSCs and facilitate the implantation of transplanted BMSCs in the cavernous body. LESWT could also enhance revascularization in the cavernous body, which might create beneficial conditions for transplanted BMSCs to survive. The combination of LESWT and BMSC transplantation was more effective in restoring erectile function in diabetic rats than LESWT or BMSC transplantation alone. |
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