Stem Cell/Oxygen-Releasing Microparticle Enhances Erectile Function in a Cavernous Nerve Injury Model

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.

The Landscape of Biomimetic Nanovesicles in Brain Diseases

Brain diseases, such as brain tumors, neurodegenerative diseases, cerebrovascular diseases, and brain injuries, are caused by various pathophysiological changes, which pose a serious health threat. Brain disorders are often difficult to treat due to the presence of the blood-brain barrier (BBB). Biomimetic nanovesicles (BNVs), including endogenous extracellular vesicles (EVs) derived from various cells and artificial nanovesicles, possess the ability to penetrate the BBB and thus can be utilized for drug delivery to the brain. BNVs, especially endogenous EVs, are widely distributed in body fluids and usually carry various disease-related signal molecules such as proteins, RNA, and DNA, and may also be analyzed to understand the etiology and pathogenesis of brain diseases. This review covers the exhaustive classification and characterization of BNVs and pathophysiological roles involved in various brain diseases, and emphatically focuses on nanotechnology-integrated BNVs for brain disease theranostics, including various diagnosis strategies and precise therapeutic regulations (e.g., immunity regulation, disordered protein clearance, anti-neuroinflammation, neuroregeneration, angiogenesis, and the gut-brain axis regulation). The remaining challenges and future perspectives regarding the nanotechnology-integrated BNVs for the diagnosis and treatment of brain diseases are also discussed and outlined.

Repeated Injections of Mesenchymal Stem Cell-Derived Exosomes Ameliorate Erectile Dysfunction in a Cavernous Nerve Injury Rat Model

PURPOSE

To evaluate the therapeutic effect of repeated injections of mesenchymal stem cell (MSC)-derived exosomes on the erectile dysfunction (ED) of bilateral cavernous nerve injury (BCNI) rat model and to identify potential target genes of these injections.

MATERIALS AND METHODS

MSC-derived exosomes were isolated using an aqueous two-phase system. Rats were randomly assigned into four groups: Normal, BCNI, exosome once, and exosome-repeat groups. After four weeks, we measured the intracavernosal pressure (ICP)/mean arterial pressure (MAP) ratio to evaluate erectile function and examined cavernous nerve tissues for histological and molecular analyses. RNA sequencing in penile tissues was used to determine differentially expressed genes and was verified by quantitative polymerase chain reaction. Human umbilical vein endothelial cells (HUVECs) were used for in vitro studies to analyze biological roles.

RESULTS

The ICP/MAP ratios in the exosome-once and exosome-repeat groups were significantly increased compared to those in the BCNI group. Interestingly, the ICP/MAP ratio showed a greater increase in the exosome-repeat group, which also showed significantly increased smooth muscle/collagen ratio, α-smooth muscle actin and neuronal nitric oxide synthase expression, and cyclic guanosine monophosphate level compared to the BCNI and exosome-once groups. Three genes were significantly differentially expressed in the exosome group, among which Ras homolog family member B promoted cell proliferation and angiogenesis of HUVECs.

CONCLUSIONS

Repeated injections of MSC-derived exosomes can be effective in the treatment of rat models with ED induced by cavernous nerve injury.

Dual Strategy with Adipose-Derived Stem Cells and l-arginine Recovered Cavernosal Functions in a Rat Model of Radical Prostatectomy

As standard therapy for prostate cancer, radical prostatectomy causes cavernous nerve (CN) injury and increases fibrosis and hypoxia-induced penile structural alterations. This study aimed to determine the potential beneficial effects of adipose-derived stem cells (ADSCs) and l-arginine alone or in combination on the penile erection in a rat model of erectile dysfunction caused by bilateral cavernous nerve transection (CNT). Male rats (n = 35) were randomized into five groups: Sham-operated; CNT (4-weeks); CNT plus ADSCs (1 × 106 cells by intracavernosal injection); CNT plus l-arginine (4 weeks, 10 mg/kg/day, oral); and ADSCs combined with l-arginine in CNT. In vivo erectile responses and in vitro relaxant responses were measured. Western blot and immunohistochemistry analyses were used to determine the expression and localization of endothelial nitric oxide synthase, neuronal nitric oxide synthase, transforming growth factor-beta 1, hypoxia-inducible factor-1 alpha (HIF-1α), and apoptosis markers (Bax and Bcl-2). The ratio of smooth muscle to collagen and nerve regeneration were calculated using Masson's trichrome and nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase staining. The combined treatment restored diminished erectile responses, endothelium-dependent acetylcholine, and electrical field stimulation-induced relaxation of the corpus cavernosum in rats with CNT, whereas either monotherapy produced only partial improvements. All treatment regimens restored increases in the protein expression of HIF-1 and Bax in rats with CNT. The decrease in smooth muscle mass and NADPH-diaphorase-positive nerve fibers was partially ameliorated by monotherapy, whereas combined therapy led to recovery. These findings indicate that combined treatment with ADSCs and l-arginine may restore erectile function in rats with CNT by inhibiting hypoxia-induced neurotoxicity and preserving endothelium function and smooth muscle content.

Recent advances in micro-sized oxygen carriers inspired by red blood cells

Supplementing sufficient oxygen to cells is always challenging in biomedical engineering fields such as tissue engineering. Originating from the concept of a 'blood substitute', nano-sized artificial oxygen carriers (AOCs) have been studied for a long time for the optimization of the oxygen supplementation and improvement of hypoxia environments in vitro and in vivo. When circulating in our bodies, micro-sized human red blood cells (hRBCs) feature a high oxygen capacity, a unique biconcave shape, biomechanical and rheological properties, and low frictional surfaces, making them efficient natural oxygen carriers. Inspired by hRBCs, recent studies have focused on evolving different AOCs into microparticles more feasibly able to achieve desired architectures and morphologies and to obtain the corresponding advantages. Recent micro-sized AOCs have been developed into additional categories based on their principal oxygen-carrying or oxygen-releasing materials. Various biomaterials such as lipids, proteins, and polymers have also been used to prepare oxygen carriers owing to their rapid oxygen transfer, high oxygen capacity, excellent colloidal stability, biocompatibility, suitable biodegradability, and long storage. In this review, we concentrated on the fabrication techniques, applied biomaterials, and design considerations of micro-sized AOCs to illustrate the advances in their performances. We also compared certain recent micro-sized AOCs with hRBCs where applicable and appropriate. Furthermore, we discussed existing and potential applications of different types of micro-sized AOCs.

An update on the current status and future prospects of erectile dysfunction following radical prostatectomy

BACKGROUND

Radical prostatectomy (RP) and radiation treatment are standard options for localized prostate cancer. Even though nerve-sparing techniques have been increasingly utilized in RP, erectile dysfunction (ED) due to neuropraxia remains a frequent complication. Erectile function recovery rates after RP remain unsatisfactory, and many men still suffer despite the availability of various therapies.

OBJECTIVE

This systematic review aims to summarize the current treatments for post-RP-ED, assess the underlying pathological mechanisms, and emphasize promising therapeutic strategies based on the evidence from basic research.

METHOD

Evaluation and review of articles on the relevant topic published between 2010 and 2021, which are indexed and listed in the PubMed database.

RESULTS

Phosphodiesterase type 5 inhibitors, intracavernosal and intraurethral injections, vacuum erection devices, pelvic muscle training, and surgical procedures are utilized for penile rehabilitation. Clinical trials evaluating the efficacy of erectogenic drugs in this setting are conflicting and far from being conclusive. The use of androgen deprivation therapy in certain scenarios after RP further exacerbates the already problematic situation and emphasizes the need for effective treatment strategies.

CONCLUSION

This article is a detailed overview focusing on the pathophysiology and mechanism of the nerve injury developed during RP and a compilation of various strategies to induce cavernous nerve regeneration to improve erectile function (EF). These strategies include stem cell therapy, gene therapy, growth factors, low-intensity extracorporeal shockwave therapy, immunophilins, and various pharmacological approaches that have induced improvements in EF in experimental models of cavernous nerve injury. Many of the mentioned strategies can improve EF following RP if transformed into clinically applicable safe, and effective techniques with reproducible outcomes.

Oxygenation therapies for improved wound healing: Current trends and technologies

Degree of oxygenation is one of the important parameters governing various processes, including cell proliferation, angiogenesis, extracellular matrix production, and even combating the microbial burden at the wound site, all...

Progress and prospect of stem cell therapy for diabetic erectile dysfunction

Diabetic erectile dysfunction (DED) is a common complication of diabetes mellitus, significantly impairing the quality of life of patients. The conventional clinical treatment still has limitations. Stem cells (SCs), as a type of cells with multidirectional or directional differentiation capability and sustainable self-renewal potential, are widely used in regenerative medicine and tissue engineering. With the continuous update of regenerative medicine theory and the success of animal experiments, SCs as a treatment for male erectile dysfunction, especially DED, have attracted widespread attention because of curable possibility. This review focus on the current progress in the clinical application of SC treatment for DED. Moreover, we summarize the development prospects of SCs in the field of DMED therapy.

Prenatal exposure to di-n-butyl phthalate induces erectile dysfunction in male adult rats

Di-n-butyl phthalate (DBP) is a widely used plasticizer and an environmental endocrine-disrupting compound. However, whether prenatal exposure to DBP can impair erectile function remains unknown. We conducted this study to investigate the potential effects of prenatal exposure to DBP on erectile function and the underlying mechanisms. A rat model of prenatal DBP exposure (12.5, 100 or 800 mg/kg/day by gavage during gestational days 13-21) was established. Prenatal DBP exposure significantly decreased penis/body weight ratio, myelin sheath thickness of cavernosum nerves and serum testosterone level in male rats at the age of 10 weeks. Furthermore, erectile dysfunction was detected in all DBP exposure groups, which exhibited substantial increases in transforming growth factor-β1 (TGF-β1) expression and decreases in the expression of alpha smooth muscle actin (α-SMA), neuronal and endothelial nitric oxide synthase (nNOS and eNOS). Additionally, the phospho-B-cell lymphoma 2 (Bcl-2)-associated death promoter (p-Bad)/Bad and phospho-the protein kinase B (p-AKT)/AKT ratios were remarkably lower, but the Bcl-2-associated X protein (Bax)/Bcl-2 ratio and caspase-3 were higher in DBP exposure groups than in the control group. Notably, prenatal exposure to DBP increase the risk of ED in male adult rats, even taking low dose of DBP (12.5 mg/kg/day). DBP exposure causing penile fibrosis, decreased testosterone level, and endothelial dysfunction may be responsible for ED by activating Akt/Bad/Bax/caspase-3 pathway and suppressing NOS/cGMP pathway in penis.

Role of regenerative therapies on erectile dysfunction after radical prostatectomy

The present study provides a review of stem cell therapy as a treatment of erectile dysfunction from peer-reviewed human and animal trials. A literature search was conducted in PubMed-Medline, Scopus, Embase, and Cochrane databases. Tweenty-three animal studies and seven human studies in the period from 1st of January 2000 to 1st of Mai 2020 were included. The seven included human studies are primary phase one trials, and most of them treat erectile dysfunction following radical prostatectomy by injection of stem cells into the corpus cavernosum. The primary outcome measure in all human trials is safety and secondary can stem cells play a role in the recovery of erectile function. All studies conclude that it is safe to use stem cells and the majority of the studies demonstrate an improvement in erectile function. The results from both animal and human trials are promising for stem cells as a restorative treatment, but data from large randomized human phase two trials is missing before it can be concluded, that stem cells is an effective treatment for erectile dysfunction in humans.