Effect of mesenchymal stem cell penile transplantation on erectile signaling of aged rats

Research Advances in Stem Cell Therapy for Erectile Dysfunction

Erectile dysfunction (ED) is a common clinical condition that mainly affects men aged over 40 years. Various causes contribute to the progression of ED, including pelvic nerve injury, diabetes, metabolic syndrome, age, Peyronie's disease, smoking, and psychological disorders. Current treatments for ED are limited to symptom relief and do not address the root cause. Stem cells, with their powerful ability to proliferate and differentiate, are a promising approach for the treatment of male ED and are gradually gaining widespread attention. Current uses for treating ED have been studied primarily in experimental animals, with most studies observing improvements in erectile quality as well as improvements in erectile tissue. However, research on stem cell therapy for human ED is still limited. This article summarizes the recent literature on basic stem cell research on ED, including cavernous nerve injury, aging, diabetes, and sclerosing penile disease, and describes mechanisms of action and therapeutic effects of various stem cell therapies in experimental animals. Stem cells are also believed to interact with host tissue in a paracrine manner, and improved function can be supported through both implantation and paracrine factors. To date, stem cells have shown some preliminary promising results in animal and human models of ED.

Recent advances in stem cell therapy for erectile dysfunction: a narrative review

INTRODUCTION

While phosphodiesterase type 5 inhibitors (PDE5is) and others are used to treat Erectile dysfunction (ED), many patients are either unresponsive or resistant to it. Stem cell therapy (SCT) is a promising alternative approach. Numerous preclinical trials have demonstrated improved erectile function in animal models using SCT, although the number of clinical trials investigating SCT for men with ED is limited. Nonetheless, findings from human clinical trials suggest that SCT may be a useful treatment option.

AREAS COVERED

Biomedical literature, including PubMed, ClinicalTrials.gov, and European Union Clinical Trials Registry, were analyzed to summarize and synthesize information on stem cell therapy for ED in this narrative review. The achievements in preclinical and clinical evaluations are presented and critically analyzed.

EXPERT OPINION

SCT has demonstrated some benefits in improving erectile function, while further studies are urgently needed. Such studies would provide valuable insights into the optimal use of stem cell therapy and its potential as a therapeutic option for ED. Taking advantage of different mechanisms of action involved in various regenerative therapies, combination therapies such as SCT and low-energy shock waves or platelet-rich plasma may provide a more effective therapy and warrant further research.

Extracellular vesicles from human urine-derived stem cells merged in hyaluronic acid ameliorate erectile dysfunction in type 2 diabetic rats by glans administration

BACKGROUND

The high prevalence of erectile dysfunction (ED) in patients with type 2 diabetes mellitus (DM2) is a challenging clinical problem. Researches on extracellular vesicles from urine-derived stem cells (USC-EVs) have shown that they have significant therapeutic effects in a variety of diseases by injection including ED. Hyaluronic acid (HA) is especially useful for delivering bioactive molecules. This study investigated the effects and related mechanisms of local administration of human USC-EVs combined with HA (USC-EVs-HA) on a rat model of DM2ED.

METHODS

UCSs were extracted from human urine samples and identified for preparation of the corresponding USC-EVs. The effects of high glucose and USC-EVs on human umbilical vein endothelial cells (HUVECs) were assessed in vitro using a CCK-8 assay to determine cell proliferation and pick the most appropriate concentration for subsequent experiments. Scratch and tube formation assays were performed to assess the function of HUVECs. Quantitative real-time polymerase chain reaction (PCR) was used to detect the expression of genes such as B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (BAX), and superoxide dismutase-2 (SOD2). HA, USC-EVs, and USC-EVs-HA were prepared at concentrations and then administered topically to DM2ED rats multiple times. Intracavernous pressure and mean arterial pressure were measured to assess erectile function in rats. Masson, Tunel, Immunohistochemistry, and Western blot analysis were performed to assess the fibrosis and endothelial function in corpus cavernosum, respectively.

RESULTS

Compared with the control group, the proliferation, migration ability, and tube-forming ability of HUVECs decreased in high glucose environment, while USC-EVs could optimize the function of HUVECs, reverse the expression of apoptotic genes, and enhance the antioxidant capacity. USC-EVs-HA showed improvement in ED compared to the HA and USC-EVs groups, and the 10-dose group was better than the 5-dose group. Histologically, the USC-EVs-HA group significantly improved apoptosis, angiogenesis, and smooth muscle regeneration in the corpus cavernosum compared to the HA group.

CONCLUSIONS

The topical application of USC-EVs-HA in the treatment of DM2ED rats has been proved effective. The potential mechanism might to promote the proliferation of endothelial cells and smooth muscle in the corpus cavernosum, which leads to the remodeling of erectile function. And multiple dosing at intervals may make the effect more pronounced.

Performance and safety of treatment options for erectile dysfunction in patients with spinal cord injury: A review of the literature

BACKGROUND

For a large proportion of patients with spinal cord injury, sexuality and reproduction are important issues. However, sparse data exist regarding available treatment options for this patient population.

OBJECTIVES

We sought to review performance and safety rates of all currently available treatment options for erectile dysfunction in spinal cord injury men.

MATERIALS AND METHODS

A systematic literature review without time restrictions was performed using PubMed/EMBASE database for English-, Italian-, German-, and Spanish-language articles. Articles' selection was performed according to the PRISMA guidelines. Relevant papers on erectile dysfunction in spinal cord injury patients were included in the final analyses.

RESULTS AND DISCUSSION

Overall, 47 studies were eligible for inclusion in this review. Of these, most evidence dealt with phosphodiesterase 5-inhibitors and intracavernous drug injection. Both treatment options are associated with high levels of performance and with patients/partners' satisfaction; side effects are acceptable. Overall, penile prostheses and vacuum erection devices are in general less approved by spinal cord injury patients and are correlated with increased rates of complications in comparison with phosphodiesterase 5-inhibitors and intracavernous drug injection. Sacral neuromodulation, transcutaneous electrical nerve stimulation, and intraurethral suppositories have been poorly studied, but preliminary studies did not show convincing results.

CONCLUSION

The best treatment options for erectile dysfunction in spinal cord injury patients emerged to be phosphodiesterase 5-inhibitors and intracavernous drug injection. The choice of erectile dysfunction treatment should be based on several aspects, including residual erectile function, spinal cord injury location, and patients' comorbidities. Future studies assessing the applicability of less well-studied treatments, as well as evaluating innovative options, are needed in this specific population.

MicroRNA-145 engineered bone marrow-derived mesenchymal stem cells alleviated erectile dysfunction in aged rats

Background

Aging is one of the dominant factors contributing to erectile dysfunction (ED), and effective treatments for age-associated ED are urgently demanded. In this study, the therapeutic efficiency of bone marrow-derived mesenchymal stem cells (BMSCs) overexpressing microRNA-145 (miR-145) was evaluated in ED.

Methods

Sixty male Sprague-Dawley rats (24 months old) were randomly divided into 4 treatment groups (n = 15/group): PBS (control), BMSCs, BMSCs transfected with a blank vector (vector-BMSCs), and BMSCs transfected with a lentivirus overexpressing miR-145 (OE-miR-145-BMSCs). Fourteen days after transplantation of BMSCs, erectile function was evaluated by measuring intra-cavernous pressure (ICP) and mean arterial pressure (MAP). Subsequently, penile erectile tissues were harvested and subjected to Masson staining, qRT-PCR, immunofluorescence staining, dual luciferase assay, and Western blot analysis.

Results

Fourteen days after transplantation, the ICP/MAP was 0.79 ± 0.05 in the OE-miR-145-BMSC group, 0.61 ± 0.06 in the BMSC group, 0.57 ± 0.06 in the vector-BMSC group, and 0.3 ± 0.01 in the PBS group. Treatment with OE-miR-145-BMSCs significantly improved ED (P < 0.05), and the treatment increased the smooth muscle content in the penis tissues of ED rats (P < 0.05). In the OE-miR-145-BMSC group, the expression levels of α-SMA, desmin, and SM-MHC were higher than they were in the other ED groups (P < 0.05). In addition, the levels of collagen 1, MMP2, and p-Smad2 in the BMSC-treated group, especially in the OE-miR-145-BMSC group, were lower than those in the control group (P < 0.05).

Conclusions

MicroRNA-145 engineered BMSCs effectively attenuate age-related ED. Transplantation of miR-145-overexpressing BMSCs may provide a promising novel avenue for age-associated ED therapy.

Advances in stem cell therapy for erectile dysfunction

INTRODUCTION

Stem cell (SC) application is a promising area of research in regenerative medicine, with the potential to treat, prevent, and cure disease. In recent years, the number of studies focusing on SCs for the treatment of erectile dysfunction (ED) and other sexual dysfunctions has increased significantly.

AREAS COVERED

This review includes critical ED targets and preclinical studies, including the use of SCs and animal models in diabetes, aging, cavernous nerve injury, and Peyronie's disease. A literature search was performed on PubMed for English articles.

EXPERT OPINION

Combination treatment offers better results than monotherapy to improve pathological changes in diabetic ED. Regenerative medicine is a promising approach for the maintenance of sexual health and erectile function later in life. Cavernous nerve regeneration and vascular recovery employing SC treatment may be focused on radical prostatectomy-induced ED. Notwithstanding, there are a number of hurdles to overcome before SC-based therapies for ED are considered in clinical settings. Paracrine action, not cellular differentiation, appears to be the principal mechanism of action underlying SC treatment of ED. Intracavernosal injection of a single SC type should be the choice protocol for future clinical trials.

Aphrodisiac Activity of Eulophia macrobulbon Extract on Erectile Dysfunction in Male Aged Rats

This study investigated the effect of Eulophia macrobulbon (EM) extract on sexual performance in aged-related erectile dysfunction (ED) rats. The ethanol EM extract at the doses of 15, 150, and 450 and sildenafil citrate at the dose of 5 mg/kg body weight (BW) were administered orally to the aged male rats once daily for 21 days. Mating parameters and intracavernosal pressure (ICP) were measured to evaluate their sexual and erection functions. Numbers of sperm and sperm motility as well as the diameter of seminiferous tubules were observed. The serum testosterone and 3',5'-cyclic guanosine monophosphate (cGMP) concentration in the rat penile tissue were analyzed. The results showed the significant increased sexual motivation, copulatory performance, and ICP of aged rats treated with sildenafil citrate and all doses of EM extract as compared to control aged rats. Moreover, their serum testosterone levels were slightly increased and significant increase in penile cGMP concentration was observed in these aged rats treated with sildenafil citrate and EM extract. The results suggest that treatment with EM could inhibit activity of PDE5 in penile tissue resulting in the increased cGMP level and bring to the improvement of erectile function and sexual performance.

Aging and sexual health: getting to the problem

Erectile dysfunction (ED) is one of the most common disorders in male and is often associated with other age-related comorbidities. The aging process affects the structural organization and function of penile erectile components such as smooth muscle cell and vascular architecture. These modifications affect penile hemodynamics by impairing cavernosal smooth muscle cell relaxation, reducing penile elasticity, compliance and promoting fibrosis. This review aims to identify the mechanisms of ED in the penile aging process in experimental and clinical data. It also highlights areas that are in need of more research. The search strategies yielded total records screened from PubMed. Clarification of the molecular mechanisms that accompanies corpus cavernosum aging and aging-associated ED will aid new perspectives in the development of novel mechanism-based therapeutic approaches. Age is not a limiting factor for ED medical management, and it is never too late to treat. Hypogonadism should be managed regardless of age, and synergistic effects have been found during testosterone (T) replacement therapy when used along with oral phosphodiesterase-5 (PDE-5) inhibitors. Therefore, the clinical management of ED related to aging can be done by therapeutic interventions that include PDE-5 inhibitors, and other pharmacological treatments.

Stem Cells in Male Sexual Dysfunction: Are We Getting Somewhere?

INTRODUCTION

Stem cells for sexual disorders are steadily being introduced into clinical trials. Two conditions of importance are the main target for this line of treatment, especially when regarding the wide array of translational and basic science highlighting the potential advantages of regenerative therapy: erectile dysfunction (ED) and more recently Peyronie disease (PD). Cellular therapy offers a treatment modality that might reverse disease progression. It would be used in a curative setting, in contrast to other pharmaceutical agents that are currently available.

AIM

To review basic preclinical studies and recent clinical trials of stem cells on ED and PD.

METHODS

A search of the medical literature for the following terms was performed using PubMed: stem cells, cellular therapy, erectile dysfunction, Peyronie's disease, and clinical trial.

MAIN OUTCOME MEASURES

A non-systematic narrative review and critical reflection on preclinical and clinical studies administering stem cells for ED and PD in animal models and human subjects.

RESULTS

Numerous studies have confirmed the beneficial functional effects of stem cell injection in established animal models on ED and PD. Various stem cell types have been adopted, from embryonic to adult mesenchymal cell types. Each cell type offers distinctive advantages and disadvantages. Diverse administrations of stem cells were investigated, with insignificant variability in the ultimate results. Stem cells appear to have a pronounced paracrine effect, rather than the classic engraftment and differentiation hypothesis. Phase 1 clinical trials using stem cells have not reported any severe adverse events in animals. However, these results cannot be extrapolated to draw any conclusions about efficacy in human patients.

CONCLUSION

Stem cells have an established efficacy in preclinical studies and early clinical trials. Studies are currently being published demonstrating the safety of intrapenile injection of autologous bone marrow- and adipose tissue-derived stem cells. Soebadi MA, Milenkovic U, Weyne E, et al. Stem Cells in Male Sexual Dysfunction: Are We Getting Somewhere? Sex Med Rev 2017;5:222-235.

Advances in stem cell research for the treatment of male sexual dysfunctions

PURPOSE OF REVIEW

To summarize recent literature on basic stem cell research in erectile dysfunction in cavernous nerve injury, aging, diabetes, and Peyronie's disease and to provide a perspective on clinical translation of these cellular therapies.

RECENT FINDINGS

Stem cell research has been concentrated on mesenchymal stem (stromal) cells from bone marrow and adipose tissue. Application of both cell types has produced positive effects on erectile function in various animal models of erectile dysfunction. In acute animal models, such as cavernous nerve injury-induced erectile dysfunction and chemically induced Peyronie's disease, engraftment and differentiation have not been observed, and stem cells are believed to interact with the host tissue in a paracrine fashion, whereas in chronic disease models some evidence suggests both engraftment and paracrine factors may support improved function. Clinical trials are now investigating therapeutic efficacy of cellular therapy, whereas the first safety studies in humans have recently been published.

SUMMARY

Evidence from preclinical studies has established stem cells as a potential curative treatment for erectile dysfunction and early phase clinical trials are currently performed.

Stem Cell Therapy for Erectile Dysfunction: Progress and Future Directions

INTRODUCTION

Erectile dysfunction (ED) is the most common sexual disorder reported by men to their health-care providers and the most investigated male sexual dysfunction. Currently, the treatment of ED focuses on symptomatic relief of ED and therefore tends to provide temporary relief rather than providing a cure or reversing the underlying cause. Recently, stem cell-based therapies have received increasing attention regarding their potential for the recovery of erectile function. Preclinical studies have shown that these cells may reverse pathophysiological changes leading to ED rather than treating the symptom ED.

AIM

To review available evidence on the efficacy and mechanisms of action of stem cell application for the treatment of ED.

METHODS

A nonsystematic review was conducted on the available English literature between 1966 and 2013 on the search engines SciVerse-sciencedirect, SciVerse-scopus, Google Scholar, and PubMed.

RESULTS

Several preclinical studies have addressed stem cell-based therapies for the recovery of erectile function following cavernous nerve injury and in Peyronie's disease, diabetes, aging, and hyperlipidemia. Overall, these studies have shown beneficial effects of stem cell therapy, while evidence on the mechanisms of action of stem cell therapy still varies between studies. While many authors propose engraftment and differentiation of stem cells, a recent paradigm shift toward paracrine mechanisms of action is observed. One clinical study investigated stem cell therapy in diabetic patients, and two more clinical trials are currently recruiting patients.

CONCLUSIONS

The development of methods to deliver stem cells to the penis has kindled a keen interest in understanding stem cell biology as it related to restoration of normal penile vascular and neuronal homeostasis. The use of stem cells for the treatment of ED represents an exciting new field, which still requires extensive basic research and human trials in diverse ED patient populations in order to define its role in the treatment of ED. Albersen M, Weyne E, and Bivalacqua TJ. Stem cell therapy for erectile dysfunction: Progress and future directions. Sex Med Rev 2013;1:50-64.

Stem cell treatment of erectile dysfunction

Erectile Dysfunction (ED) is a common disease that typically affects older men. While oral type-5 phosphodieserase inhibitors (PDE5Is) represent a successful first-line therapy, many patients do not respond to this treatment leading researchers to look for alternative treatment modalities. Stem cell (SC) therapy is a promising new frontier for the treatment of those patients and many studies demonstrated its therapeutic effects. In this article, using a Medline database search of all relevant articles, we present a summary of the scientific principles behind SCs and their use for treatment of ED. We discuss specifically the different types of SCs used in ED, the methods of delivery tested, and the methods attempted to enhance SC therapy effect. In addition, we review the current preclinical literature on SC therapy for ED and present a summary of its findings in addition to the single clinical trial published.

Stem cell therapy for erectile dysfunction

Erectile dysfunction (ED) is an important health problem that has commonly been clinically treated using phosphodiesterase type 5 inhibitors (PDE5Is). However, PDE5Is are less effective when the structure of the cavernous body has been severely injured, and thus regeneration is required. Stem cell therapy has been investigated as a possible means for regenerating the injured cavernous body. Stem cells are classified into embryonic stem cells and adult stem cells (ASCs), and the intracavernous injection of ASCs has been explored as a therapy in animal ED models. Bone marrow-derived mesenchymal stem cells and adipose tissue-derived stem cells are major sources of ASCs used for the treatment of ED, and accumulated evidence now suggests that ASCs are useful in the restoration of erectile function and the regeneration of the cavernous body. However, the mechanisms by which ASCs recover erectile function remain controversial. Some studies indicated that ASCs were differentiated into the vascular endothelial cells, vascular smooth muscle cells, and nerve cells that originally resided in the cavernous body, whereas other studies have suggested that ASCs improved erectile function via the secretion of anti-apoptotic and/or proangiogenic cytokines rather than differentiation into other cell types. In this paper, we reviewed the characteristics of stem cells used for the treatment of ED, and the possible mechanisms by which these cells exert their effects. We also discussed the problems to be solved before implementation in the clinical setting.

Advances in Stem Cell Therapy for Erectile Dysfunction

Stem cell (SC) therapy for erectile dysfunction (ED) has been investigated in 35 published studies, with one being a small-scale clinical trial. Out of these 35 studies, 19 are concerned with cavernous nerve (CN) injury-associated ED while 10 with diabetes mellitus- (DM-) associated ED. Adipose-derived SCs (ADSCs) were employed in 18 studies while bone marrow SCs (BMSCs) in 9. Transplantation of SCs was done mostly by intracavernous (IC) injection, as seen in 25 studies. Allogeneic and xenogeneic transplantations have increasingly been performed but their immune-incompatibility issues were rarely discussed. More recent studies also tend to use combinatory therapies by modifying or supplementing SCs with angiogenic or neurotrophic genes or proteins. All studies reported better erectile function with SC transplantation, and the majority also reported improved muscle, endothelium, and/or nerve in the erectile tissue. However, differentiation or engraftment of transplanted SCs has rarely been observed; thus, paracrine action is generally believed to be responsible for SC’s therapeutic effects. But still, few studies actually investigated and none proved paracrine action as a therapeutic mechanism. Thus, based exclusively on functional outcome data shown in preclinical studies, two clinical trials are currently recruiting patients for treatment with IC injection of ADSC and BMSC, respectively.

Stem-cell therapy for erectile dysfunction

INTRODUCTION

Stem cells (SCs) have been investigated for the treatment of erectile dysfunction (ED).

AREAS COVERED

This review covers key disease targets and all 33 preclinical studies, including their use of SC types, animal models, transplantation routes, and outcome assessment methods.

EXPERT OPINION

In the past one and half years there have been more stem-cell-for-erectile-dysfunction studies than the prior 8 years combined. These new studies tend to use combinatory treatment approaches by modifying or supplementing SCs with angiogenic or neurotrophic genes or proteins. However, when considering all risks and benefits, these combinatory approaches do not seem more advantageous than single-SC approaches. Another trend is the choice of transplantation routes other than the standard intracavernous (IC) injection. However, with the exception of intravenous injection, these new transplantation approaches are more cumbersome than IC injection and yet offer no evidence of producing better outcomes. In contrast to these variations, a consensus among these studies is the suggestion that paracrine action, as opposed to cellular differentiation, is the principal therapeutic mechanism. In conclusion, IC injection of a single SC type should be the choice protocol for initial clinical trials, and this is clearly the case with two clinical trials that are currently recruiting patients.

Stem-cell therapy for erectile dysfunction

INTRODUCTION

Erectile dysfunction (ED) is the most common sexual disorder that men report to healthcare providers, and is the male sexual dysfunction that has been most investigated. Current treatments for ED focus on relieving the symptoms of ED and therefore tend to provide a temporary solution rather than a cure or reversing the cause. Recently, therapies based on stem cells (SCs) have had an increasing attention for their potential to restore erectile function. Preclinical studies showed that these cells might reverse the pathophysiological changes leading to ED, rather than treating the symptoms of ED. This review is intended to provide an overview of contemporary reports on the use of SCs to treat ED.

METHODS

We made an extensive search for reports on SC-based therapy for the management of ED, published in English between 1966 and 2013, using the search engines SciVerse-sciencedirect, SciVerse-scopus, Google Scholar and Pubmed, with the search terms 'erectile dysfunction', 'stem cells', 'multipotent stromal cells', 'adipose (tissue) derived stem cells', 'bone-marrow derived stem cells', 'animal model', 'diabetes', 'ageing', 'Peyronie's Disease' and 'cavernous nerve injury'.

RESULTS

Fifty-four papers were identified and contributed, either as an original research report or review thereof, to this review. Several preclinical studies addressed SC-based therapies for the recovery of erectile function caused by a variety of both chronic and acute conditions. Overall, these studies showed beneficial effects of SC therapy, while evidence on the mechanisms of action of SC therapy varied between studies. One clinical trial investigated the short-term effects of SC therapy in diabetic patients with ED. Two more clinical trials are currently recruiting patients.

CONCLUSIONS

The rapidly expanding and highly promising body of preclinical work on SC-based medicine providing a potential cure for ED, rather than merely symptom relief, is indicative of the increasing interest in regenerative options for sexual medicine over the past decade. Clinical trials are currently recruiting patients to test the preclinical results in men with ED.

Intracavernous administration of bone marrow mononuclear cells: a new method of treating erectile dysfunction?

While PDE5 inhibitors have revolutionized treatment of ED, approximately 30% of patients are non-responsive. A significant cause of this is vascular and smooth muscle dysfunction, as well as nerve atrophy. Autologous administration of bone marrow mononuclear cells (BMMC) has been performed in over 2000 cardiac patients without adverse effects, for stimulation of angiogenesis/regeneration. Despite its ease of access, and dependence on effective vasculature for function, comparatively little has been perform in terms of BMMC therapy for ED. Here we outline the rationale for use of autologous BMMC in patients with ED, as well as provide early safety data on the first use of this procedure clinically.

Emerging tools for erectile dysfunction: a role for regenerative medicine

Erectile dysfunction (ED) is the most common sexual disorder reported by men to their health-care providers and the most investigated male sexual dysfunction. Currently, the treatment of ED focuses on 'symptomatic relief' of ED and, therefore, tends to provide temporary relief rather than providing a cure or reversing the cause. The identification of a large population of "difficult-to-treat" patients has triggered researchers to identify novel treatment approaches, which focus on cure and restoration of the underlying cause of ED. Regenerative medicine has developed extensively in the past few decades and preclinical trials have emphasized the benefit of growth factor therapy, gene transfer, stem cells and tissue engineering for the restoration of erectile function. Development of clinical trials involving immunomodulation in postprostatectomy ED patients and the use of maxi-K channels for gene therapy are illustrative of the advances in the field. However, the search for novel treatment targets and a wealth of preclinical studies represent a dynamic and continuing field of enquiry.

Effects of a water-soluble curcumin protein conjugate vs. pure curcumin in a diabetic model of erectile dysfunction

INTRODUCTION

Curcumin is involved in erectile signaling via elevation of cyclic guanosine monophosphate (cGMP).

AIM

Assessment of the effects of water-soluble curcumin in erectile dysfunction (ED).

METHODS

One hundred twenty male white albino rats were divided into: 1st and 2nd control groups with or without administration of Zinc protoporphyrin (ZnPP), 3rd and 4th diabetic groups with or without ZnPP, 5th diabetic group on single oral dose of pure curcumin, 6th diabetic group on pure curcumin administered daily for 12 weeks, 7th and 8th diabetic groups on single dose of water-soluble curcumin administered with or without ZnPP, 9th and 10th diabetic groups on water-soluble curcumin administered daily for 12 weeks with or without ZnPP. All curcumin dosage schedules were administered after induction of diabetes.

MAIN OUTCOME MEASURES

Quantitative gene expression of endothelial nitric oxide synthase (eNOS), neuronal NOS (nNOS), inducible NOS (iNOS), heme oxygenase-1 (HO-1), nuclear transcription factor-erythroid2 (Nrf2), NF-Кβ, and p38. Cavernous tissue levels of HO and NOS enzyme activities, cGMP and intracavernosal pressure (ICP).

RESULTS

Twelve weeks after induction of diabetes, ED was confirmed by the significant decrease in ICP. There was a significant decrease in cGMP, NOS, HO enzymes, a significant decrease in eNOS, nNOS, HO-1 genes and a significant elevation of NF-Кβ, p38, iNOS genes. Administration of pure curcumin or its water-soluble conjugate led to a significant elevation in ICP, cGMP levels, a significant increase in HO-1 and NOS enzymes, a significant increase in eNOS, nNOS, HO-1, and Nrf2 genes, and a significant decrease in NF-Кβ, p38, and iNOS genes. Water-soluble curcumin showed significant superiority and more prolonged duration of action. Repeated doses regimens were superior to single dose regimen. Administration of ZnPP significantly reduced HO enzyme, cGMP, ICP/ mean arterial pressure (MAP), HO-1 genes in diabetic groups.

CONCLUSION

Water-soluble curcumin could enhance erectile function with more effectiveness and with more prolonged duration of action.

Stem cells: novel players in the treatment of erectile dysfunction

Stem cells are defined by their capacity for both self-renewal and directed differentiation; thus, they represent great promise for regenerative medicine. Historically, stem cells have been categorized as either embryonic stem cells (ESCs) or adult stem cells (ASCs). It was previously believed that only ESCs hold the ability to differentiate into any cell type, whereas ASCs have the capacity to give rise only to cells of a given germ layer. More recently, however, numerous studies demonstrated the ability of ASCs to differentiate into cell types beyond their tissue origin. The aim of this review was to summarize contemporary evidence regarding stem cell availability, differentiation, and more specifically, the potential of these cells in the diagnosis and treatment of erectile dysfunction (ED) in both animal models and human research. We performed a search on PubMed for articles related to definition, localisation and circulation of stem cells as well as the application of stem cells in both diagnosis and treatment of ED. Strong evidence supports the concept that stem cell therapy is potentially the next therapeutic approach for ED. To date, a large spectrum of stem cells, including bone marrow mesenchymal stem cells, adipose tissue-derived stem cells and muscle-derived stem cells, have been investigated for neural, vascular, endothelial or smooth muscle regeneration in animal models for ED. In addition, several subtypes of ASCs are localized in the penis, and circulating endogenous stem cells can be employed to predict the outcome of ED and ED-related cardiovascular diseases.

Multipotent stromal cell therapy for cavernous nerve injury-induced erectile dysfunction

INTRODUCTION

Erectile dysfunction (ED) following radical prostatectomy (RP) is a result of inadvertent damage to the cavernous nerves that run close to the prostate capsula. The mechanisms behind the development of post-RP ED are increasingly recognized and include cavernosal fibrosis and cavernosal smooth muscle apoptosis, resulting from cavernous nerve degeneration due to neuropraxia. In recent years, cell-based therapies have received increasing attention regarding their potential for recovery of erectile function following cavernous nerve injury (CNI). Multipotent stromal cells (MSCs) are an attractive cell source for this application based on their regenerative potential and their clinical applicability.

AIM

To review available evidence on the efficacy and mechanisms of action of MSC application for the treatment of ED, with an emphasis on ED following CNI.

METHODS

A nonsystematic review was conducted on the available English literature between 1966 and 2011 on the search engines SciVerse-sciencedirect, SciVerse-scopus, Google Scholar, and PubMed.

RESULTS

MSCs from both bone marrow and adipose tissue have shown beneficial effects in a variety of animal models for ED. While MSC application in chronic disease models such as diabetes, aging, and hyperlipidemia may result in cell engraftment and possibly MSC differentiation, this observation has not been made in the acute CNI rat model. In the latter setting, MSC effects seem to be established by cell recruitment toward the major pelvic ganglion and local paracrine interaction with the host neural tissue.

CONCLUSIONS

While the type of model may influence the mechanisms of action of this MSC-based therapy, MSCs generally display efficacy in various animal models for ED. Before translation to the clinic is established, various hurdles need to be overcome.

Stem cell therapy for erectile dysfunction: a critical review

Erectile dysfunction (ED) is a prevailing health problem that seriously impacts quality of life. Current treatment options are less effective for patients having cavernous nerve (CN) injury or diabetes mellitus-related ED. These 2 types of ED are thus the main focus of past and current stem cell (SC) therapy studies. In a total of 16 studies so far, rats were exclusively used as disease models and SCs were mostly derived from bone marrow, adipose tissue, or skeletal muscle. For tracking, SCs were labeled with LacZ, green fluorescent protein, 4',6-diamidino-2-phenylindole, DiI, bromodeoxyuridine, or 5-ethynyl-2-deoxyuridine, some of which might have led to data misinterpretation. SC transplantation was done exclusively by intracavernous (IC) injection, which has been recently shown to have systemic effects. Functional assessment was done exclusively by measuring increases of IC pressure during electrostimulation of CN. Histological assessment usually focused on endothelial, smooth muscle, and CN contents in the penis. In general, favorable outcomes have been obtained in all trials so far, although whether SCs had differentiated into specific cell lineages remains controversial. Recent studies have shown that intracavernously injected SCs rapidly escaped the penis and homed into bone marrow. This could perhaps explain why intracavernously injected SCs had systemic antidiabetic effects and prolonged anti-ED effects. These hypotheses and the differentiation-versus-paracrine debate require further investigation.

Tracking intracavernously injected adipose-derived stem cells to bone marrow

Intracavernous (IC) injection of stem cells (SCs) has been shown to improve erectile function in various erectile dysfunction (ED) animal models. However, the tissue distribution of the injected cells remains unknown. In this study we tracked IC injected adipose-derived stem cells (ADSCs) in various tissues. Rat paratesticular fat was processed for ADSC isolation and culture. The animals were then subject to cavernous nerve (CN) crush injury or sham operation, followed by IC injection of one million autologous or allogeneic ADSCs that were labeled with 5-ethynyl-2-deoxyuridine (EdU). Another group of rats received IC injection of EdU-labeled allogeneic penile smooth muscle cells (PSMCs). At 2 and 7 days post-injection, penises and femoral bone marrow were processed for histological analyses. Whole femoral bone marrows were also analyzed for EdU-positive cells by flow cytometry. The results show that ADSCs exited the penis within days of IC injection and migrated preferentially to bone marrow. Allogenicity did not affect ADSC's bone marrow appearance either at 2 or 7 days, while CN injury reduced the number of ADSCs in bone marrow significantly at 7 but not 2 days. The significance of these results in relation to SC therapy for ED is discussed.

Reversion of penile fibrosis: Current information and a new horizon

Ageing has a detrimental effect on cavernous tissue and the tunica albuginea of the penis. Furthermore, atherosclerosis of the penile vessels that occurs with ageing causes a decrease in penile oxygen tension. A reduction in smooth muscle cells (SMCs) was shown in relation to diminution of oxygen tension. Chronic ischaemia is therefore not only associated with fibrosis but also with nitric oxide-cyclic guanosine monophosphate reduction. The sensitivity of the α-adrenoceptors on the SMCs increases with ageing. The decrease in penile elasticity and compliance are explained by the changes in the ratio of penile collagen that occur with ageing. Contradictory to the view that testosterone is only necessary for sexual desire, numerous recent studies showed that androgen deprivation produces penile tissue atrophy, alterations in dorsal nerve structure, alterations in endothelial morphology, reduction in trabecular SM content, increase in deposition of extracellular matrix and accumulation of fat-containing cells (adipocytes) in the subtunical region of corpus cavernosum. The aim of the current review is to shed some light on the underlying aetiology of corporal fibrosis especially ageing, cavernous nerve damage, androgen deprivation and tunical fibrosis. Ultimately I will address the proposed prevention of erectile dysfunction associated with penile fibrosis.