Effect of basic fibroblast growth factor incorporating gelatin microspheres on erectile function in the diabetic rat

Vasohibin-1 rescues erectile function through up-regulation of angiogenic factors in the diabetic mice

Neovascularization of the erectile tissue emerges as a beneficial curative approach to treat erectile dysfunction (ED). Here we for the first time report the unexpected role of vasohibin-1 (VASH1), mainly known as an anti-angiogenic factor, in restoring erectile function in diabetic mice. A diabetic patient has lower cavernous VASH1 expression than in the potent man. VASH1 was mainly expressed in endothelial cells. There were significant decreases in cavernous endothelial cell and pericyte contents in VASH1 knockout mice compared with those in wild-type mice, which resulted in impairments in erectile function. Intracavernous injection of VASH1 protein successfully restored erectile function in the diabetic mice (~ 90% of control values). VASH1 protein reinstated endothelial cells, pericytes, and endothelial cell–cell junction proteins and induced phosphorylation of eNOS (Ser1177) in the diabetic mice. The induction of angiogenic factors, such as angiopoietin-1 and vascular endothelial growth factor, is responsible for cavernous angiogenesis and the restoration of erectile function mediated by VASH1. Altogether, these findings suggest that VASH1 is proangiogenic in diabetic penis and is a new potential target for diabetic ED.

Intracavernous delivery of Dickkopf3 gene or peptide rescues erectile function through enhanced cavernous angiogenesis in the diabetic mouse

BACKGROUND

Severe peripheral angiopathy in patients with diabetes is a major contributing factor for low response rate to phosphodiesterase-5 inhibitors.

OBJECTIVES

To examine whether and how Dickkopf3 (DKK3), a secreted modulator of the Wnt pathway that known to be involved in endothelial cell repair and vascular progenitor cell migration, restores erectile function in diabetic mice.

METHODS

Eight-week-old C57BL/6 mice received intraperitoneal injections of streptozotocin (50 mg/kg for 5 days). Eight weeks after the diabetes was induced, the efficacy of DKK3 was determined by three independent experiments: experiment 1 (DKK3 peptide [5 μg in 20 μL PBS]); experiment 2 (DKK3 plasmid DNA with electroporation [10, 40, or 100 μg in 20 μL PBS, respectively]); and experiment 3 (DKK3 adenovirus [1 × 10⁷ , 1 × 10⁸ , 1 × 10⁹ virus particles per 20 μL, respectively]). Erectile function was measured by electrical stimulation of the cavernous nerve one week (for peptide) or two weeks (for genes) after treatment. The angiogenic activity of DKK3 was determined in diabetic penis in vivo and in primary cultured mouse cavernous endothelial cells (MCECs) in vitro.

RESULTS

The cavernous expression of DKK3 protein was significantly lower in the diabetic mice than in controls. DKK3 peptide or adenovirus significantly improved erectile function in diabetic mice (70% of the control values). DKK3 adenovirus profoundly restored cavernous endothelial cell and pericyte contents and increased endothelial junction proteins in diabetic mice in vivo. DKK3 peptide induced upregulation of angiogenic factors (angiopoietin-1, vascular endothelial growth factor, and basic fibroblast growth factor) and accelerated tube formation in MCECs cultivated under the high-glucose condition in vitro.

CONCLUSION

DKK3 restored cavernous vascular integrity and improved erectile function in diabetic mice. Therapeutic cavernous angiogenesis by the use of DKK3 will be a promising therapeutic strategy to treat diabetic erectile dysfunction.

Shengjing Capsule Improves Erectile Function Through Regulation of Nitric Oxide-induced Relaxation in Corpus Cavernosum Smooth Muscle in a Castrated Rat Model

OBJECTIVE

To evaluate the effects of Shengjing capsule on erectile function in a castrated rat model, and further to investigate the underlying molecular mechanism.

MATERIALS AND METHODS

Thirty male Sprague-Dawley rats were randomly divided into six groups (n = 5 per group), including sham group, castration group, testosterone replacement group, high-dose Shengjing capsule group, medium-dose Shengjing capsule group, and low-dose Shengjing capsule group. The weight of the body and androgen-sensitive organs, and the serum level of testosterone were assessed. Erectile function was evaluated using cavernous nerve electrical stimulation after treatment. Corpus cavernosum tissue was examined by Masson's trichrome staining, immunohistochemistry, quantitative reverse transcriptase-polymerase chain reaction, and Western blot.

RESULTS

Serum testosterone level, mean weights of body, and accessory sexual organs were not significantly different between Shengjing capsule treatment and the castration groups (P > .05 for all). Significant recovery of erectile function and the increased smooth muscle components were observed in the Shengjing capsule treatment group as compared with the castration group (P < .01 and P < .01, respectively). The gene and protein expression of 3 subtypes of nitric oxide synthase (NOS)-neuronal (nNOS), inducible (iNOS), and endothelial (eNOS) -in cavernous tissue in Shengjing capsule-treated rats were significantly higher than in the castration group (P < .05 for all). Phosphodiesterase type 5 messenger ribonucleic acid and protein expression in each group followed a trend similar to that of smooth muscle content.

CONCLUSION

These results show that Shengjing capsule improves the erectile function by protecting the smooth muscle content and enhancing NOS activity in penile tissues of castrated male rats.

Animal model for the study of the relationship between lower urinary tract symptoms/bladder outlet obstruction and erectile dysfunction

OBJECTIVES

Lower urinary tract symptoms (LUTS) are frequently associated with erectile dysfunction (ED) in aged men, and both significantly influence quality of life. However, the mechanism linking LUTS to ED has not been clarified completely. The purpose of the present study was to establish an animal model of ED following LUTS/bladder outlet obstruction (BOO) and investigate the expression of molecules related to the cause of this type of ED.

METHODS

Male Sprague-Dawley rats with partial BOO were used as an experimental model of LUTS. Sham-operated animals served as controls. Voiding and erectile function were evaluated 4, 8, and 16 weeks after obstruction or sham operation. The mRNA expression of penile tissue genes related to penile corporal smooth muscle relaxation was examined by quantitative real-time reverse transcription-polymerase chain reaction.

RESULTS

Voiding and bladder function of BOO rats were significantly worse than in sham-operated rats 4, 8, and 16 weeks after obstruction. The erectile function of BOO rats was significantly decreased compared with that of the sham-operated controls (P < 0.01) 16 weeks after obstruction, although it was similar to that of sham-operated animals at 4 and 8 weeks after obstruction. The expression of endothelial nitric oxide synthase (eNOS) mRNA was significantly decreased 16 weeks after obstruction compared with that in sham-operated rats (P < 0.01).

CONCLUSION

An animal model for investigations into the association between LUTS and ED is described herein. Endothelial dysfunction induced by impaired eNOS function is likely to be involved in ED following LUTS/BOO.

Advances in the study of the peripheral nervous system for erection in animals and humans

Introduction

Since Walsh first emphasized the importance of preserving the neurovascular bundle n to protect the cavernous nerve during pelvic surgery, patients' sexual life quality has dramatically improved. Today, nerve-sparing radical prostatectomy is the established gold standard for organ-confined prostate cancer patients. Recent technical advances in functional assessment such as intraoperative electrical stimulation have unveiled new anatomical features and physiological roles. Basic research has advanced understanding of cavernous nerve function, while molecular biology has uncovered the crucial role of neuronal nitric oxide in mediating erection, and has led to new treatments such as phosphodiesterase type-5 inhibitors. A recent focus in cavernous nerve research concerns the nerve distribution external to the neurovascular bundle. The cavernous nerves in humans appear to be distributed more widely beneath the lateral pelvic fascia than in other animals, and electrical stimulation studies suggest possible involvement of these nerves in erection. These findings have prompted new surgical techniques such as the "veil of Aphrodite", or "intrafascial nerve-sparing" procedures.

Materials and Methods

These recent anatomical and physiological studies in humans and animals and their impact are reviewed in this article.

Conclusions

Further investigation should stimulate future advances in strategies to preserve erectile function in RP patients.

Transplantation of nonhematopoietic adult bone marrow stem/progenitor cells isolated by p75 nerve growth factor receptor into the penis rescues erectile function in a rat model of cavernous nerve injury

PURPOSE

Radical prostatectomy for prostate cancer frequently results in erectile dysfunction and decreased quality of life. We investigated the effects of transplanting nonhematopoietic adult bone marrow stem/progenitor cells (multipotent stromal cells) into the corpus cavernosum in a rat model of bilateral cavernous nerve crush injury.

MATERIALS AND METHODS

Multipotent stromal cells were isolated from the bone marrow of transgenic green fluorescent protein rats by plastic adherence (rat multipotent stromal cells) or magnetic activated cell sorting using antibodies against p75 low affinity nerve growth factor receptor (p75 derived multipotent stromal cells). Bilateral cavernous nerve crush injury was induced in adult male Sprague-Dawley rats. Immediately after injury 8 rats each were injected intracavernously with phosphate buffered saline (vehicle control), fibroblasts (cell control), rat multipotent stromal cells (cell treatment) or p75 derived multipotent stromal cells (cell treatment). Another 8 rats underwent sham operation (phosphate buffered saline injection). Four weeks after the procedures we assessed erectile function by measuring the intracavernous-to-mean arterial pressure ratio and total intracavernous pressure during cavernous nerve stimulation.

RESULTS

Intracavernous injection of p75 derived multipotent stromal cells after bilateral cavernous nerve crush injury resulted in a significantly higher mean intracavernous-to-mean arterial pressure ratio and total intracavernous pressure compared with all other groups except the sham operated group (p <0.05). Rats injected with typical multipotent stromal cells had partial erectile function rescue compared with animals that received p75 derived multipotent stromal cells. Fibroblast (cell control) and phosphate buffered saline (vehicle control) injection did not improve erectile function. Enzyme-linked immunosorbent assay suggested that basic fibroblast growth factor secreted by p75 derived multipotent stromal cells protected the cavernous nerve after bilateral cavernous nerve crush injury.

CONCLUSIONS

Transplantation of adult stem/progenitor cells may provide an effective treatment for erectile dysfunction after radical prostatectomy.

Abnormal protein expression in the corpus cavernosum impairs erectile function in type 2 diabetes

OBJECTIVE

To investigate the changes in corporal relaxation, intracavernous pressure (ICP) and associated protein expression that control normal erectile function in rats with type 2 diabetes (T2D), as this disease is part of the 'metabolic syndrome' associated with a high rate of erectile dysfunction (ED) in men, resulting from failure of corpus cavernosum-mediated processes.

MATERIALS AND METHODS

T2D was induced in rats by feeding them with a high-fat diet (HFD) followed by an injection with low-dose streptozotocin (STZ); they were then compared with rats that received a normal diet (ND).

RESULTS

Hyperglycaemia and dyslipidaemia were induced in HFD + STZ rats, suggesting that T2D was established. The rats with T2D had associated ED, as both nonadrenergic noncholinergic-mediated corporal relaxation and increased ICP by cavernous nerve stimulation were significantly attenuated compared to the ND group. Western blot analysis revealed diabetes-associated lower expression of endothelial and neuronal nitric oxide synthase (e and nNOS), and cGMP-dependent protein kinase (PKG)-1alpha/beta expression in penile tissue than in the ND group. Contrary to the proteins that regulate corporal relaxation, there were relatively high levels of RhoA/Rho kinase receptor 1 (ROCK1) and ET-A receptor (ETAR) in T2D rats. However, the expressed level of phosphodiesterase-5 and insulin-like growth factor binding protein 3 was not altered significantly in response to T2D.

CONCLUSION

Decreased expression of certain proteins that mediate the relaxant mechanism, associated with increased expression of certain proteins that mediate contractile mechanisms, might be important in the development of T2D-associated ED. In particular, down-regulated eNOS/nNOS/PKG1 as well as up-regulated ETAR/RhoA/ROCK1 might participate in the aetiology of ED in T2D.

Controlled release of heparin-binding growth factors using heparin-containing particulate systems for tissue regeneration

The strategy of growth factor delivery to specific sites for therapeutic applications has been considered an essential process in biomedical fields despite some obstacles, such as a non-controlled release with initial burst. This article focuses on particulate systems using heparin for the controlled delivery of heparin-binding growth factors (HBGFs), an emerging area in the tissue engineering field. Since heparin has been widely utilized for growth factor delivery due to its electrostatic nature and specific affinity with HBGFs, heparin-containing polymeric particulates can be utilized as functional carriers to deliver growth factors in a controlled manner. In particular, examples of the HBGF delivery systems containing heparin, perspectives and potential applications are described and discussed.

Insulin-like growth factor-1 restores erectile function in aged rats: modulation the integrity of smooth muscle and nitric oxide-cyclic guanosine monophosphate signaling activity

INTRODUCTION

Insulin-like growth factor-1 (IGF-1) is one of the growth factors that have a wide range of biologic effects. We have confirmed that gene transfer of IGF-1 to the penis could improve erectile capacity. However, there are some limitations in gene therapies, such as toxicity or a risk of insertional mutagenesis. Protein treatment may be another choice for decreasing these risks.

AIM

To investigate whether intracavernosal injection of IGF-1 protein can restore erectile function in the aging rat.

MAIN OUTCOME MEASURES

Erectile responses, morphological changes, and nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling pathways-related marker were determined.

METHODS

Ten young (4 months) and 30 old (24 months) Sprague-Dawley male rats were enrolled in this study. The old rats were divided into three groups: vehicle-only (N = 10), IGF-1 1 microg/kg (N = 10) and IGF-1 10 microg/kg treatment group (N = 10). After 4 and 8 weeks of single IGF-1 injection treatment, intracavernous pressure (ICP) responses with electrical stimulation to the cavernous nerve were evaluated. The percent of smooth muscle in corpus cavernosum tissue, the expression of mRNA and protein of endothelial nitric oxide synthase (eNOS) were also evaluated. The activity of nitric oxide synthase (NOS) and concentration of guanosine 3',5'-cyclic-monophosphate (cGMP) that act upon the major NO-cGMP signaling pathways in penile tissue were also analyzed.

RESULTS

After IGF-1 treatment, the ICP responses was significantly increased as the young control group in both the IGF-1 1 microg/kg and the IGF-1 10 microg/kg group compared with the vehicle-only group at 4 and 8 weeks (P < 0.05). Masson's trichrom staining showed the percentage of cavernosal smooth muscle was increased in IGF-1 treatment group. IGF-1 increased e-NOS expression. NOS activities and cGMP concentrations were also significantly increased in IGF-1 treatment rats.

CONCLUSIONS

IGF-1 improved erectile function in aged rats via restoration the integrity of smooth muscle of corpus cavernosum and modulation of NO-cGMP pathways.

Heparin conjugated polymeric micelle for long-term delivery of basic fibroblast growth factor

Heparin conjugated amphiphilic block copolymer, Tetronic-PCL-heparin (TCH), was developed and its polymeric micelles (PMs) were prepared as an injectable vehicle for long-term delivery of bFGF, which is one of the heparin-binding growth factors (HBGF). TCH PMs were fabricated by a single emulsion and solvent evaporation method. The structural properties of TCH were confirmed by (1)H NMR, FT-IR and GPC. The contents of bound heparin were 0.44 micro g/micro g and the heparin activity by APTT assay was 43.6% when compared to free heparin. The critical micelle concentration (CMC) of TCH PMs was approximately 0.11 g/l. The diameter of TC micelle was approximately 25 nm and its size after conjugation of heparin was increased to 114 nm due to the heparin molecules on the shell of the micelle. The bFGF loading amount of TCH PMs was considerably higher than that of TC, caused by specific interactions between heparin and bFGF. In vitro study, bFGF was released from TCH PMs in a controlled manner over 2 months. The results demonstrated that TCH PMs become a novel candidate for the long-term delivery of various growth factors with heparin-binding domain in tissue engineering.

Diabetic erectile dysfunction--an indicator of generalised endothelial function per se?

Erectile dysfunction (ED) affects up to 70% of men with diabetes. However, the pathophysiology of ED in diabetes remains uncertain with both neuronal and vascular factors cited. We examined whether ED is an indicator of generalized endothelial dysfunction. A unique group of diabetic patients free from established conventional cardiac risk factors were investigated. Forearm bloodflow responses to nitroprusside and acetylcholine on 11 diabetic men with ED and 11 potent diabetic men were measured by venous plethysmography. Patient characteristics between the impotent and potent patients were similar except for Hba1c which was higher in the group with ED (8.35% vs. 7.03%: p = 0.003). Both groups showed increases in FBF to incremental infusions of nitroprusside and acetylcholine but the area under curve (AUC) were similar in the ED and the non-ED groups (p = 0.16 and p = 0.17, respectively). We demonstrated that ED in patients with type 2 diabetes is not associated with additional generalized endothelial dysfunction.

Endothelial dysfunction in diabetic erectile dysfunction

Erectile dysfunction (ED) is highly prevalent in diabetes mellitus. Pathophysiological mechanisms underlying diabetes-associated ED are in large part due to endothelial dysfunction, which functionally refers to the inability of the endothelium to produce vasorelaxing messengers and to maintain vasodilation and vascular homeostasis. The precise mechanisms leading to endothelial dysfunction in the diabetic vasculature, including the penis, are not yet fully understood. Hyperglycemia affects endothelial nitric oxide synthase activity and nitric oxide production/bioavailability, nitric oxide-independent relaxing factors, oxidative stress, production and/or action of hormones, growth factors and/or cytokines, and generation and activity of opposing vasoconstrictors. Considering recent advances in the field of vascular biology and diabetes, the emphasis in this review is placed on the mechanisms of hyperglycemia-induced endothelial dysfunction in the pathophysiology of diabetes-associated ED.

ORIGINAL RESEARCH—BASIC SCIENCE: Intracavernosal Basic Fibroblast Growth Factor Improves Vasoreactivity in the Hypercholesterolemic Rabbit

PURPOSE

We determined the effects of intracavernosal injection (ICI) of recombinant basic fibroblast growth factor (rbFGF) on corporal tissue in hypercholesterolemic rabbits.

METHODS

Twenty New Zealand White rabbits were fed a 1% cholesterol diet for 6 weeks and were randomly divided into four groups. Group 1 (N = 5) received an ICI of phosphate buffered saline solution (PBS) once and again 3 weeks later. Group 2 (N = 4) received an ICI of 2.5 microg rbFGF once and PBS 3 weeks later. Group 3 (N = 6) received an ICI of 2.5 microg rbFGF once and again 3 weeks later. Group 4 (N = 5) received an ICI of 2.5 microg rbFGF once. All animals were maintained on the high cholesterol diet until sacrifice, 3 weeks after last injection. Strips of corporal tissue were submaximally contracted with norepinephrine, and dose-response curves were generated to evaluate endothelial-dependent (acetylcholine, ACH) and endothelial-independent (sodium nitroprusside, SNP) vasoreactivity. Protein levels of bFGF and vascular endothelial growth factor (VEGF) were assessed by enzyme-linked immunosorbent assay. Neuronal nitric oxide synthase (nNOS) protein and mRNA were detected by Western blot and semi-quantitative polymerase chain reaction, respectively.

RESULTS

Vasoreactivity was improved by bFGF treatment as shown by higher ED50[-log(M)] of ACH and SNP in Groups 2, 3, and 4. The expression of bFGF protein, VEGF protein, nNOS protein, and mRNA were all increased after bFGF treatment.

CONCLUSIONS

ICI of bFGF improved vasoreactivity in hypercholesterolemic rabbit corporal tissue, offering a new direction to explore for the treatment of erectile dysfunction.