Generation of intracellular ROS, real-time changes in intracellular Ca(2+), ROS-dependent stress fibre formation, and the disassembly of the adherens junctions were studied by a confocal microscopy in human umbilical vein endothelial cells (HUVECs). VEGF-induced vascular leakage was investigated in the skin of diabetic mice using a Miles vascular permeability assay. Microvascular leakage in the retina of streptozotocin diabetic mice was investigated using a confocal microscopy after left ventricle injection of fluorescein isothiocyanate (FITC)-dextran. C-peptide inhibited the VEGF-induced ROS generation, stress fibre formation, disassembly of vascular endothelial cadherin, and endothelial permeability in HUVECs. Intradermal injection of C-peptide prevented VEGF-induced vascular leakage. Consistent with this, intravitreal injection of C-peptide prevented the extravasation of FITC-dextran in the retinas of diabetic mice, which was also prevented by anti-VEGF antibody and ROS scavengers in diabetic mice. Conclusions/interpretation C-peptide prevents VEGF-induced microvascular permeability by inhibiting ROS-mediated intracellular events in diabetic mice, suggesting that C-peptide replacement is a promising therapeutic strategy to prevent diabetic retinopathy.

Pericytes are known to play critical roles in vascular development and homeostasis. However, the distribution of cavernous pericytes and their roles in penile erection is unclear. Herein we report that the pericytes are abundantly distributed in microvessels of the subtunical area and dorsal nerve bundle of mice, followed by dorsal vein and cavernous sinusoids. We further confirmed the presence of pericytes in human corpus cavernosum tissue and successfully isolated pericytes from mouse penis. Cavernous pericyte contents from diabetic mice and tube formation of cultured pericytes in high glucose condition were greatly reduced compared with those in normal conditions. Suppression of pericyte function with anti-PDGFR-β blocking antibody deteriorated erectile function and tube formation in vivo and in vitro diabetic condition. In contrast, enhanced pericyte function with HGF protein restored cavernous pericyte content in diabetic mice, and significantly decreased cavernous permeability in diabetic mice and in pericytes-endothelial cell co-culture system, which induced significant recovery of erectile function. Overall, these findings showed the presence and distribution of pericytes in the penis of normal or pathologic condition and documented their role in the regulation of cavernous permeability and penile erection, which ultimately explore novel therapeutics of erectile dysfunction targeting pericyte function.

Diabetes mellitus disrupts wound repair and leads to the development of chronic wounds, likely due to impaired angiogenesis. We previously demonstrated that human proinsulin C-peptide can protect against vasculopathy in diabetes; however, its role in impaired wound healing in diabetes has not been studied. We investigated the potential roles of C-peptide in protecting against impaired wound healing by inducing angiogenesis using streptozotocin-induced diabetic mice and human umbilical vein endothelial cells. Diabetes delayed wound healing in mouse skin, and C-peptide supplement using osmotic pumps significantly increased the rate of skin wound closure in diabetic mice. Furthermore, C-peptide induced endothelial cell migration and tube formation in dose-dependent manners, with maximal effect at 0.5 nM. These effects were mediated through activation of extracellular signal-regulated kinase 1/2 and Akt, as well as nitric oxide formation. C-peptide-enhanced angiogenesis in vivo was demonstrated by immunohistochemistry and Matrigel plug assays. Our findings highlight an angiogenic role of C-peptide and its ability to protect against impaired wound healing, which may have significant implications in reparative and therapeutic angiogenesis in diabetes. Thus, C-peptide replacement is a promising therapy for impaired angiogenesis and delayed wound healing in diabetes.

Penile erection is a neurovascular phenomenon, and erectile dysfunction (ED) is caused mainly by vascular risk factors or diseases, neurologic abnormalities, and hormonal disturbances. Men with diabetic ED often have severe endothelial dysfunction and peripheral nerve damage, which result in poor response to oral phosphodiesterase-5 inhibitors. Nerve injury-induced protein 1 (Ninjurin 1, Ninj1) is known to be involved in neuroinflammatory processes and to be related to vascular regression during the embryonic period. Here, we demonstrate in streptozotocin-induced diabetic mice that inhibition of the Ninj1 pathway by administering Ninj1-neutralizing antibody (Ninj1-Ab) or by using Ninj1-knockout mice successfully restored erectile function through enhanced penile angiogenesis and neural regeneration. Angiopoietin-1 (Ang1) expression was down-regulated and angiopoietin-2 expression was up-regulated in the diabetic penis compared with that in controls, and these changes were reversed by treatment with Ninj1-Ab. Ninj1 blockade-mediated penile angiogenesis and neural regeneration as well as recovery of erectile function were abolished by inhibition of Ang1-Tie2 (tyrosine kinase with Ig and epidermal growth factor homology domain-2) signaling with soluble Tie2 antibody or Ang1 siRNA. The present results suggest that inhibition of the Ninj1 pathway will be a novel therapeutic strategy for treating ED.diabetes mellitus | male sexual dysfunction | peripheral neuropathy E rectile dysfunction (ED), which is defined as an inability to attain or maintain penile erection sufficient for satisfactory sexual intercourse (1), is caused by a variety of pathologic conditions including vascular risk factors or diseases, neurologic abnormalities, and hormonal disturbances (2, 3). Diabetes mellitus is one of the most common causes of ED, and about 50-75% of male diabetic patients have ED (4, 5). Multiple pathogenetic factors, such as endothelial dysfunction, atherosclerosis, autonomic neuropathy, inflammation, fibrosis, and hypogonadism, are involved in diabetic ED (4-6). The multiple factors causing diabetic ED contribute to reduced responsiveness to currently available oral phosphodiesterase-5 (PDE5) inhibitors, which enhance the nitric oxide (NO)-cGMP pathway by inhibiting the breakdown of cGMP (7). The severity of endothelial dysfunction and peripheral neuropathy are mainly responsible for the poor responsiveness of diabetic patients to PDE5 inhibitors (8, 9). Because the effects of PDE5 inhibitors depend on endogenous NO formation, PDE5 inhibitors fail to increase the cGMP level above the threshold required for penile erection if bioavailable NO is insufficient as the result of severe endothelial dysfunction or peripheral neuropathy (9). Therefore, a new treatment strategy that corrects both endothelial dysfunction and peripheral neuropathy is required for men with diabetic ED.A variety of strategies targeting therapeutic angiogenesis and neural regeneration have been introduced to restore erectile function at the preclinical lev...

Introduction Transforming growth factor-β1 (TGF-β1) has been identified as an important fibrogenic cytokine associated with Peyronie’s disease (PD). Aim The aim of this study was to study the differential expression of the TGF-β1 and Smad transcription factors in plaque tissue from PD patients and to determine the antifibrotic effect of SKI2162 (SK Chemicals, Seoul, South Korea), a novel small-molecule inhibitor of activin receptor-like kinase 5 (ALK5), a type I receptor of TGF-β, in primary fibroblasts derived from human PD plaque. Methods Plaque tissue was isolated from five PD patients, and tunica albuginea tissue was obtained from four control patients. Plaque tissues from a patient with PD were used for primary fibroblast culture. Fibroblasts were pretreated with SKI2162 (10 µM) and then stimulated with TGF-β1 (10 ng/mL). Main Outcome Measures The plaque or tunica albuginea tissue was stained with Masson’s trichrome or antibody to TGF-β1, phospho-Smad2 (P-Smad2), and P-Smad3. Protein was extracted from treated fibroblasts for Western blotting, and the membranes were probed with antibody to P-Smad2/Smad2, P-Smad3/Smad3, plasminogen activator inhibitor-1, fibronectin, collagen I, and collagen IV. We also determined the inhibitory effect of SKI2162 on TGF-β1-induced nuclear translocation of Smad2/3 in fibroblasts. Results The plaque tissue from PD patients showed higher TGF-β1, P-Smad2, and P-Smad3 immunoreactivity than did the tunica albuginea tissue from control patients. SKI2162 not only blocked TGF-β1-induced phosphorylation and nuclear translocation of Smad2 and Smad3, but also inhibited the production of extracellular matrix markers in fibroblasts derived from human PD plaque. Conclusion In light of the pivotal role of TGF-β and Smads in the pathogenesis of PD, pharmacologic inhibition of ALK5 may represent a novel targeted approach to treating PD.