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OBJECTIVE--Patients with diabetic erectile dysfunction often have severe endothelial dysfunction and respond poorly to oral phosphodiesterase-5 inhibitors. We examined the effectiveness of the potent angiopoietin-1 (Ang1) variant, cartilage oligomeric matrix protein (COMP)-Ang1, in promoting cavernous endothelial regeneration and restoring erectile function in diabetic animals. RESEARCH DESIGN AND METHODS--Four groups of mice were used: controls; streptozotocin (STZ)-induced diabetic mice; STZ-induced diabetic mice treated with repeated intracavernous injections of PBS; and STZ-induced diabetic mice treated with COMP-Ang1 protein (days -3 and 0). Two and 4 weeks after treatment, we measured erectile function by electrical stimulation of the cavernous nerve. The penis was harvested for histologic examinations, Western blot analysis, and cGMP quantification. We also performed a vascular permeability test. RESULTS--Local delivery of the COMP-Ang1 protein significantly increased cavernous endothelial proliferation, endothelial nitric oxide (NO) synthase (NOS) phosphorylation, and cGMP expression compared with that in the untreated or PBS-treated STZ-induced diabetic group. The changes in the group that received COMP-Ang1 restored erectile function up to 4 weeks after treatment. Endothelial protective effects, such as marked decreases in the expression of p47phox and inducible NOS, in the generation of superoxide anion and nitrotyrosine, and in the number of apoptotic cells in the corpus cavernosum tissue, were noted in COMP-Ang1-treated STZ-induced diabetic mice. An intracavernous injection of COMP-Ang1 completely restored endothelial cell-cell junction proteins and decreased cavernous endothelial permeability. COMP-Ang1-induced promotion of cavernous angiogenesis and erectile function was abolished by the NOS inhibitor, N-nitro-L-arginine methyl ester, but not by the NADPH oxidase inhibitor, apocynin. CONCLUSIONS--These findings support the concept of cavernous endothelial regeneration by use of the recombinant Ang1 protein as a curative therapy for diabetic erectile dysfunction. [ABSTRACT FROM AUTHOR]

Patients with erectile dysfunction (ED) associated with type II diabetes often have impaired endothelial function and tend to respond poorly to oral phosphodiesterase type 5 inhibitors. Therefore, neovascularization is a promising strategy for curing diabetic ED. To determine the effectiveness of a soluble, stable, and potent angiopoietin-1 (Ang1) variant, cartilage oligomeric matrix protein (COMP)-Ang1, in promoting cavernous angiogenesis and erectile function in a mouse model of type II diabetic ED. Sixteen-week-old male db/db mice (in which obesity and type II diabetes are caused by a mutation in the leptin receptor) and control C57BL/6J mice were used and divided into four groups (N = 14 per group): age-matched controls; db/db mice receiving two successive intracavernous injections of phosphate-buffered saline (PBS) (days −3 and 0; 20 µL); db/db mice receiving a single intracavernous injection of COMP-Ang1 protein (day 0; 5.8 µg/20 µL); and db/db mice receiving two successive intracavernous injections of COMP-Ang1 protein (days −3 and 0; 5.8 µg/20 µL). Two weeks later, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was then harvested and stained with antibodies to platelet/endothelial cell adhesion molecule-1 (PECAM-1) (endothelial cell marker), phosphohistone H3 (PH3, a nuclear protein indicative of cell proliferation), phospho-endothelial nitric oxide synthase (eNOS), and eNOS. Penis specimens from a separate group of animals were used for cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) quantification. Local delivery of COMP-Ang1 protein significantly increased eNOS phosphorylation and cGMP and cAMP expression compared with that in the group treated with PBS. Repeated intracavernous injections of COMP-Ang1 protein completely restored erectile function and cavernous endothelial content through enhanced cavernous neoangiogenesis as evaluated by PECAM-1 and PH3 immunohistochemistry and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling assay, whereas a single injection of COMP-Ang1 protein elicited partial improvement. Cavernous neovascularization using recombinant Ang1 protein is a novel therapeutic strategy for the treatment of ED resulting from type II diabetes. [ABSTRACT FROM AUTHOR]

Introduction. With the advent of genetically modified mice, it seems particularly advantageous to develop a mouse model of diabetic erectile dysfunction. Aim. To establish a mouse model of type I diabetes by implementation of either multiple low-dose streptozotocin (STZ) protocol or single high-dose STZ protocol and to evaluate morphologic alterations in the cavernous tissue and subsequent derangements in penile hemodynamics in vivo. Methods. Eight-week-old C57BL/6J mice were divided into three groups: a control group, a group administered the multiple low-dose STZ protocol (50 mg/kg × 5 days), and a group administered the single high-dose STZ protocol (200 mg/kg). Main Outcome Measures. After 8 weeks, erectile function was measured by electrical stimulation of the cavernous nerve. The penis was then harvested and stained with hydroethidine (in situ analysis of superoxide anion), TUNEL, or antibodies to nitrotyrosine (marker of peroxynitrite formation), PECAM-1, smooth muscle α-actin, and phospho-eNOS. Penis specimens from a separate group of animals were used for phospho-eNOS and eNOS western blot or cGMP determination. Results. Erectile function was significantly less in diabetic groups than in control group. The generation of superoxide anion and nitrotyrosine and the number of apoptotic cells in both cavernous endothelial and smooth muscle cells were significantly higher in diabetic groups than in control group. Cavernous tissue phospho-eNOS and cGMP expression and the number of endothelial and smooth muscle cells were lower in diabetic groups than in control group. Both diabetic models resulted in similar structural and functional derangements in the corpus cavernosum; however, the mortality rate was higher in mice receiving single high-dose of STZ than in those receiving multiple low-doses. Conclusion. The mouse model of type I diabetes is useful and technically feasible for the study of the pathophysiologic mechanisms involved in diabetic erectile dysfunction. Jin H-R, Kim WJ, Song JS, Choi MJ, Piao S, Shin SH, Tumurbaatar M, Tuvshintur B, Nam M-S, Ryu J-K, and Suh, J-K. Functional and morphologic characterizations of the diabetic mouse corpus cavernosum: comparison of a multiple low-dose and a single high-dose streptozotocin protocols. J Sex Med 2009;6:3289–3304. [ABSTRACT FROM AUTHOR]

The synthesis of extracellular matrix (ECM) in mesangial cells (MCs) plays important roles in the development and progression of renal diseases, including chronic allograft nephropathy. Mycophenolic acid (MPA), an inhibitor of inosine monophosphate dehydrogenase 2 (IMPDH2), suppresses MC proliferation and ECM synthesis. However, the exact inhibitory mechanism of MPA on MCs has not been clearly elucidated. In this study we compared the inhibitory effects of MPA and IMPDH2 reduction [by using small interfering RNA (siRNA)] on oleic acid (OA)-induced fibronectin secretion and cellular reactive oxygen species (ROS) in mouse MCs. Growth-arrested MCs were stimulated with OA in the presence or absence of MPA, IMPDH2 siRNA, N-acetylcysteine (NAC), transforming growth factor beta (TGF-β) antibody or exogenous guanosine. Fibronectin secretion into the medium was examined by Western blot, dichlorodihydrofluorescein (DCF)-sensitive cellular ROS by fluorescence-activated cell scanning (FACS), TGF-β levels in the media by enzyme-linked immunosorbent assay (ELISA). OA increased fibronectin secretion, TGF-β and cellular ROS levels. A TGF-β neutralizing antibody effectively suppressed OA-induced fibronectin secretion. NAC and MPA completely suppressed OA-induced fibronectin secretion and decreased the levels of TGF-β and cellular ROS. However, IMPDH2 siRNA partly inhibited OA-induced MC activation. Exogenous guanosine successfully reversed the inhibitory effects of IMPDH2 siRNA on OA-induced MC activation. Pleiotropic inhibitory effect of MPA on OA-induced mouse MC activation was mediated via its antioxidant effect on cellular ROS production and partly via inhibition of IMPDH2 itself. Our results implicate ROS as an alternative therapeutic target for the prevention of hyperlipidemia-related glomerulopathy, chronic allograft nephropathy, and subsequent graft loss. [ABSTRACT FROM AUTHOR]