Transcriptional profiling of mouse cavernous pericytes under high-glucose conditions: Implications for diabetic angiopathy

Revisiting experimental models of erectile dysfunction and their value in drug discovery and development

INTRODUCTION

Erectile dysfunction (ED) is a common condition that often signals underlying endothelial dysfunction, although the underlying causative factor(s) are likely complex and multifactorial. Various animal models have been developed to provide a research platform to study ED and served as an important basis for the discovery and subsequent development of novel therapeutic drugs for ED.

AREAS COVERED

The review article provides an overview of various animal models in ED research with an emphasis on important drug target discovery relating to each specific experimental model. The authors highlight translation from basic science research to major preclinical and clinical studies in this evolving field of ED research.

EXPERT OPINION

Animal models simulate the pathological features of various types of ED and clarify their molecular mechanisms. These mechanisms aid in discovering drug targets, while established ED models also provide a basis for validating drug efficacy, safety, and specific action mechanisms. The development of techniques in detection methods, cellular experimental, and omics has a profound impact on disease prediction, model evaluation, and optimization of therapeutic modalities. On this basis, many drug therapies targeting these ED-related mechanisms, especially in the nitric oxide/cyclic guanosine monophosphate pathways have been applied in preclinical studies. However, focusing on drug development for those types of ED where phosphodiesterase 5 inhibitor therapy is limited may be more valuable.

Role of pericytes in regulating penile angiogenesis and nerve regeneration

ABSTRACT

Pericytes are multifunctional mural cells that surround the abluminal wall of endothelial cells and are associated with vascular development, vascular permeability, and angiogenesis. Additionally, pericytes demonstrate stem cell-like properties and contribute to neuroinflammatory processes. Pericytes have been extensively studied in the central nervous system. However, specific mechanisms underlying its involvement in various physiological and pathological conditions, especially in erectile dysfunction (ED), remain poorly understood. Advancements in in vitro and in vitro techniques, such as single-cell RNA sequencing, are expanding our understanding of pericytes. Recent studies have shown that pericyte dysfunction is considered an important factor in the pathogenesis of vascular and neurological ED. Therefore, this study aims to analyze the specific role of pericytes in ED, focusing on diabetic and neurogenic ED. This article provides a comprehensive review of research findings on PubMed from 2000 to 2023, concerning pericyte dysfunction in the process of ED, offering valuable insights, and suggesting directions for further research.

Single-cell transcriptome analysis of cavernous tissues reveals the key roles of pericytes in diabetic erectile dysfunction

Erectile dysfunction (ED) affects a significant proportion of men aged 40-70 and is caused by cavernous tissue dysfunction. Presently, the most common treatment for ED is phosphodiesterase 5 inhibitors; however, this is less effective in patients with severe vascular disease such as diabetic ED. Therefore, there is a need for development of new treatment, which requires a better understanding of the cavernous microenvironment and cell-cell communications under diabetic condition. Pericytes are vital in penile erection; however, their dysfunction due to diabetes remains unclear. In this study, we performed single-cell RNA sequencing to understand the cellular landscape of cavernous tissues and cell type-specific transcriptional changes in diabetic ED. We found a decreased expression of genes associated with collagen or extracellular matrix organization and angiogenesis in diabetic fibroblasts, chondrocytes, myofibroblasts, valve-related lymphatic endothelial cells, and pericytes. Moreover, the newly identified pericyte-specific marker, Limb Bud-Heart (Lbh), in mouse and human cavernous tissues, clearly distinguishing pericytes from smooth muscle cells. Cell-cell interaction analysis revealed that pericytes are involved in angiogenesis, adhesion, and migration by communicating with other cell types in the corpus cavernosum; however, these interactions were highly reduced under diabetic conditions. Lbh expression is low in diabetic pericytes, and overexpression of LBH prevents erectile function by regulating neurovascular regeneration. Furthermore, the LBH-interacting proteins (Crystallin Alpha B and Vimentin) were identified in mouse cavernous pericytes through LC-MS/MS analysis, indicating that their interactions were critical for maintaining pericyte function. Thus, our study reveals novel targets and insights into the pathogenesis of ED in patients with diabetes.

MicroRNA-148a-3p in pericyte-derived extracellular vesicles improves erectile function in diabetic mice by promoting cavernous neurovascular regeneration

BACKGROUND

To investigate the regulatory role of microRNA (miR)-148a-3p in mouse corpus cavernous pericyte (MCPs)-derived extracellular vesicles (EVs) in the treatment of diabetes-induced erectile dysfunction (ED).

METHODS

Mouse corpus cavernous tissue was used for MCP primary culture and EV isolation. Small-RNA sequencing analysis was performed to assess the type and content of miRs in MCPs-EVs. Four groups of mice were used: control nondiabetic mice and streptozotocin-induced diabetic mice receiving two intracavernous injections (days - 3 and 0) of phosphate buffered saline, MCPs-EVs transfected with reagent control, or MCPs-EVs transfected with a miR-148a-3p inhibitor. miR-148a-3p function in MCPs-EVs was evaluated by tube-formation assay, migration assay, TUNEL assay, intracavernous pressure, immunofluorescence staining, and Western blotting.

RESULTS

We extracted EVs from MCPs, and small-RNA sequencing analysis showed miR-148a-3p enrichment in MCPs-EVs. Exogenous MCPs-EV administration effectively promoted mouse cavernous endothelial cell (MCECs) tube formation, migration, and proliferation, and reduced MCECs apoptosis under high-glucose conditions. These effects were significantly attenuated in miR-148a-3p-depleted MCPs-EVs, which were extracted after inhibiting miR-148a-3p expression in MCPs. Repetitive intracavernous injections of MCPs-EVs improved erectile function by inducing cavernous neurovascular regeneration in diabetic mice. Using online bioinformatics databases and luciferase report assays, we predicted that pyruvate dehydrogenase kinase-4 (PDK4) is a potential target gene of miR-148a-3p.

CONCLUSIONS

Our findings provide new and reliable evidence that miR-148a-3p in MCPs-EVs significantly enhances cavernous neurovascular regeneration by inhibiting PDK4 expression in diabetic mice.

Regenerative therapies as a potential treatment of erectile dysfunction

Erectile dysfunction (ED) is the most common sexual dysfunction disease in adult males. ED can be caused by many factors, such as vascular disease, neuropathy, metabolic disturbances, psychosocial causes, and side effects of medications. Although current oral phosphodiesterase type 5 inhibitors can achieve a certain effect, they cause temporary dilatation of blood vessels with no curative treatment effects. Emerging targeted technologies, such as stem cell therapy, protein therapy, and low-intensity extracorporeal shock wave therapy (Li-ESWT), are being used to achieve more natural and long-lasting effects in treating ED. However, the development and application of these therapeutic methods are still in their infancy, and their pharmacological pathways and specific mechanisms have not been fully discovered. This article reviews the preclinical basic research progress of stem cells, proteins, and Li-ESWT therapy, as well as the current status of clinical application of Li-ESWT therapy.

Bibliometric and visualization analysis of literature relating to diabetic erectile dysfunction

Introduction

Diabetic erectile dysfunction (DMED) refers to erectile dysfunction secondary to diabetes. Erectile dysfunction is characterized by a persistent inability to achieve and maintain an erection sufficient to permit satisfactory sexual activity.

Methods

Based on the Web of Science core collection database, we firstly analyzed the quantity and quality of publications in the field of DMED, secondly profiled the publishing groups in terms of country, institution, author's publication and cooperation network, and finally sorted out and summarized the hot topics of research.

Results

From 2001 to 2022, a total of 1,403 articles relating to this topic were published in 359 journals. They represent the global research status, potential hotspots, and future research directions. The number of DMED-related publications and citations has steadily increased over the few past decades. Academic institutions from Europe and the United States have played a leading role in DMED research. The country, institution, journal, and author with the most publications were the United States (294), INHA University (39), the Journal of Sexual Medicine (156), and Ryu, Ji-Kan (29), respectively. The most common keywords were erectile dysfunction (796), men (256), diabetes (254), diabetes mellitus (239), prevalence (180), corpus cavernosum (171), dysfunction (155), mellitus (154), nitric-oxide synthase (153), and expression (140). The main keyword-based research topics and hotspots in the DMED field were oral sildenafil, smooth muscle relaxation, nitric oxide synthase, gene therapy, metabolic syndrome, cavernous nerve injury, stem cell, and penile prosthesis.

Discussion

The terms oral sildenafil, smooth muscle relaxation, nitric oxide synthase, gene therapy, metabolic syndrome, cavernous nerve injury, stem cell, and penile prosthesis will be at the forefront of DMED-related research.

Pericyte-derived heme-binding protein 1 promotes angiogenesis and improves erectile function in diabetic mice

PURPOSE

To comprehensively evaluate the effect on angiogenesis of heme-binding protein 1 (Hebp1) in the treatment of diabetes-induced erectile dysfunction.

MATERIALS AND METHODS

Mouse corpus cavernosum endothelial cells and pericytes were used for in vitro study. Four groups of mice were used: control nondiabetic mice and streptozotocin-induced diabetic mice receiving two intracavernous injections of phosphate-buffered saline, Hebp1 (1 µg), or Hebp1 (5 µg). The function of Hebp1 in diabetic conditions was evaluated by tube formation assay, aorta ring assay, migration assay, intracavernous pressure, immunofluorescence staining, and Western blot experiments.

RESULTS

We report that Hebp1 is more highly expressed in mouse corpus cavernosum pericytes and can effectively promote endothelial cell angiogenesis under high-glucose conditions. Following exogenous administration of Hebp1 protein, we found that elevated Hebp1 levels can improve the erectile function of diabetic mice, which is achieved by reducing reactive oxygen species levels and activating the PI3K/AKT/eNOS signaling pathway.

CONCLUSIONS

Our findings demonstrate that Hebp1 can promote angiogenesis and improve erectile function under diabetic conditions.