Sonic hedgehog delivery from self-assembled nanofiber hydrogels reduces the fibrotic response in models of erectile dysfunction

Sonic hedgehog suppresses penile remodeling after cavernous nerve injury and sustains long-term normal penis morphology

BACKGROUND

Cavernous nerve (CN) injury, which occurs in prostatectomy and diabetic cases, initiates penile remodeling, including smooth muscle apoptosis and increased collagen in the corpora cavernosa, which are underlying causes of erectile dysfunction. Sonic hedgehog (SHH) is a critical regulator of penile smooth muscle, and SHH treatment suppresses corpora cavernosa remodeling that occurs with CN injury.

AIM

We examine if SHH treatment by peptide amphiphile (PA) in the first week after CN injury is sufficient to prevent long-term penis remodeling and if apoptosis inhibitors also suppress penile remodeling.

METHODS

Bilateral CN crush was performed on adult Sprague-Dawley rats (P115-120) that underwent 1 of 3 treatments with novel extended-release nanofiber PA hydrogels for delivery: SHH protein (n = 10), mouse serum albumin protein (control, n = 7), or caspase 3 inhibitor (AC-DEVD-CHO, n = 10). Rats were sacrificed after 18 to 24 days. Additional rats underwent CN injury (n = 6) or CN injury and SHH PA treatment for 2 and 4 days (n = 8) and included sham controls (n = 3) and nonsurgery controls (n = 3).

OUTCOMES

Trichrome stain, hydroxyproline assay, and Western analysis for α-actin (smooth muscle) and GAPDH were performed to examine smooth muscle retention and collagen abundance.

RESULTS

Smooth muscle decreased with CN injury. Corpora cavernosa showed increased smooth muscle at 2, 4, and 24 days after CN injury with SHH PA treatment in comparison with mouse serum albumin treatment among CN-injured controls. Caspase 3-inhibited penis demonstrated little smooth muscle preservation. Collagen was decreased 23% with SHH PA treatment (P < .001) at 18 to 24 days after CN injury. Collagen was unchanged with caspase 3 inhibitor treatment (P > .99).

CLINICAL TRANSLATION

It is important to know that treatments given at the time of CN injury have a sustained effect on preserving penile architecture and thus erectile function, making them valuable for clinical translation.

STRENGTHS AND LIMITATIONS

SHH PA treatment preserves penile smooth muscle after CN injury. Time points past 24 days were not examined, although penile remodeling takes place acutely after CN injury. Measurement of erectile function was not examined.

CONCLUSIONS

SHH treatment by PA in the first week after CN injury is sufficient to suppress penile remodeling and to preserve penile smooth muscle over time, which is critical to prevent development of erectile dysfunction. There is a difference in the corpora cavernosa smooth muscle from proximal to distal in the penis of the Sprague-Dawley rat model. It is critical when examining therapy efficacy to ensure that comparable regions of the penis are analyzed.

STATEMENT OF SIGNIFICANCE

In this study, we examine if suppression of apoptosis in penile smooth muscle in the first week after cavernous nerve injury is sufficient to preserve smooth muscle long-term.

Research advances in Peyronie's disease: a comprehensive review on genomics, pathways, phenotypic manifestation, and therapeutic targets

INTRODUCTION

Penile induration disease, commonly known as Peyronie's disease (PD), is a connective tissue disorder that affects the penis, leading to the development of fibrous plaques, penile curvature, and erectile dysfunction. PD is a common male reproductive system disease with a complex etiology involving multiple genes, signaling pathways, and different phenotypes.

OBJECTIVES

The etiology and pathogenesis of PD remain poorly understood, hindering the development of effective treatment strategies. By understanding the underlying mechanisms of PD, we can pave the way for targeted therapies and improved patient outcomes.

METHODS

We reviewed the epidemiology and pathophysiology of PD. We performed database searches on Google Scholar, PubMed, Medline, and Web of Science from inception to September 2023. The literature reviewed included priapism guidelines, review articles, current trial studies, and various literature related to PD.

RESULTS

This article provides a comprehensive overview of the current research progress on the disease, focusing on its genetic factors, signaling pathways, cellular mechanisms, phenotypic manifestations, and therapeutic targets. It can help identify individuals at higher risk, aid in early detection and intervention, and provide insights into fibrosis and tissue remodeling. It can also reveal potential therapeutic targets, guide accurate diagnoses and treatment strategies, and address the impact of the disease on patients' quality of life.

CONCLUSION

By integrating insights from genomics, molecular pathways, clinical phenotypes, and therapeutic potentials, our research aims to achieve a deeper and more comprehensive understanding of PD, propelling the field toward innovative strategies that enhance the lives of those affected by PD. The complex manifestations and pathogenesis of PD necessitate the use of multiple treatment methods for personalized care.

BMP4 and GREM1 are targets of SHH signaling and downstream regulators of collagen in the penis

BACKGROUND

Cavernous nerve (CN) injury, caused by prostatectomy and diabetes, initiates a remodeling process (smooth muscle apoptosis and increased collagen) in the corpora cavernosa of the penis of patients and animal models that is an underlying cause of erectile dysfunction (ED), and the Sonic hedgehog (SHH) pathway plays an essential role in the response of the penis to denervation, as collagen increases with SHH inhibition and decreases with SHH treatment.

AIM

We examined if part of the mechanism of how SHH prevents penile remodeling and increased collagen with CN injury involves bone morphogenetic protein 4 (BMP4) and gremlin1 (GREM1) and examined the relationship between SHH, BMP4, GREM1, and collagen in penis of ED patients and rat models of CN injury, SHH inhibition, and SHH, BMP4, and GREM1 treatment.

METHODS

Corpora cavernosa of Peyronie's disease (control), prostatectomy, and diabetic ED patients were obtained (N = 30). Adult Sprague Dawley rats (n = 90) underwent (1) CN crush (1-7 days) or sham surgery; (2) CN injury and BMP4, GREM1, or mouse serum albumin (control) treatment via Affi-Gel beads or peptide amphiphile (PA) for 14 days; (3) 5E1 SHH inhibitor, IgG, or phosphate-buffered saline (control) treatment for 2 to 4 days; or (4) CN crush with mouse serum albumin or SHH for 9 days.

OUTCOMES

Immunohistochemical and Western analysis for BMP4 and GREM1, and collagen analysis by hydroxyproline and trichrome stain were performed.

RESULTS

BMP4 and GREM1 proteins were identified in corpora cavernosa smooth muscle of prostatectomy, diabetic, and Peyronie's patients, and in rat smooth muscle, sympathetic nerve fibers, perineurium, blood vessels, and urethra. Collagen decreased 25.4% in rats with CN injury and BMP4 treatment (P = .02) and increased 61.3% with CN injury and GREM1 treatment (P = .005). Trichrome stain showed increased collagen in rats treated with GREM1. Western analysis identified increased BMP4 and GREM1 in corpora cavernosa of prostatectomy and diabetic patients, and after CN injury (1-2 days) in our rat model. Localization of BMP4 and GREM1 changed with SHH inhibition. SHH treatment increased the monomer form of BMP4 and GREM1, altering their range of signaling.

CLINICAL IMPLICATIONS

A better understanding of penile remodeling and how fibrosis occurs with loss of innervation is essential for development of novel ED therapies.

STRENGTHS AND LIMITATIONS

The relationship between SHH, BMP4, GREM1, and collagen is complex in the penis.

CONCLUSION

BMP4 and GREM1 are downstream targets of SHH that impact collagen and may be useful in collaboration with SHH to prevent penile remodeling and ED.

SHH regulates penile morphology and smooth muscle through a mechanism involving BMP4 and GREM1

BACKGROUND

The cavernous nerve (CN) is frequently damaged in prostatectomy and diabetic patients with erectile dysfunction (ED), initiating changes in penile morphology including an acute and intense phase of apoptosis in penile smooth muscle and increased collagen, which alter penile architecture and make corpora cavernosa smooth muscle less able to relax in response to neurotransmitters, resulting in ED.

AIM

Sonic hedgehog (SHH) is a critical regulator of penile smooth muscle, and SHH treatment suppresses penile remodeling after CN injury through an unknown mechanism; we examine if part of the mechanism of how SHH preserves smooth muscle after CN injury involves bone morphogenetic protein 4 (BMP4) and gremlin1 (GREM1).

METHODS

Primary cultures of smooth muscle cells were established from prostatectomy, diabetic, hypertension and Peyronie's (control) (N = 18) patients. Cultures were characterized by ACTA2, CD31, P4HB, and nNOS immunohistochemical analysis. Patient smooth muscle cell growth was quantified in response to BMP4 and GREM1 treatment. Adult Sprague Dawley rats underwent 1 of 3 surgeries: (1) uninjured or CN-injured rats were treated with BMP4, GREM1, or mouse serum albumin (control) proteins via Affi-Gel beads (N = 16) or peptide amphiphile (PA) (N = 26) for 3 and 14 days, and trichrome stain was performed; (2) rats underwent sham (N = 3), CN injury (N = 9), or CN injury and SHH PA treatment for 1, 2, and 4 days (N = 9).

OUTCOMES

Western analysis for BMP4 and GREM1 was performed; (3) rats were treated with 5E1 SHH inhibitor (N = 6) or IgG (control; N = 6) for 2 and 4 days, and BMP4 and GREM1 localization was examined. Statistics were performed by analysis of variance with Scheffé's post hoc test.

RESULTS

BMP4 increased patient smooth muscle cell growth, and GREM1 decreased growth. In rats, BMP4 treatment via Affi-Gel beads and PA increased smooth muscle at 3 and 14 days of treatment. GREM1 treatment caused increased collagen and smooth muscle at 3 days, which switched to primarily collagen at 14 days. CN injury increased BMP4 and GREM1, while SHH PA altered Western band size, suggesting alternative cleavage and range of BMP4 and GREM1 signaling. SHH inhibition in rats increased BMP4 and GREM1 in fibroblasts.

CLINICAL IMPLICATIONS

Understanding how SHH PA preserves and regenerates penile morphology after CN injury will aid development of ED therapies.

STRENGTHS AND LIMITATIONS

SHH treatment alters BMP4 and GREM1 localization and range of signaling, which can affect penile morphology.

CONCLUSION

Part of the mechanism of how SHH regulates corpora cavernosa smooth muscle involves BMP4 and GREM1.

Nanotechnology in sexual medicine

Statement of Significance: There is significant potential for improvement in erectile function and prevention of erectile dysfunction if these diverse and novel nanotherapies can be translated to the clinic.

Ultrasound-targeted microbubble destruction mediates PDE5i/NO integration for cavernosum remodeling and penile rehabilitation

Erectile dysfunction (ED) caused by cavernous nerve injury (CNI) is refractory to heal mainly ascribed to the adverse remodeling of the penis induced by ineffectual microvascular perfusion, fibrosis, and neurotrophins scarcity in cavernosum. Phosphodiesterase type V inhibitors (PDE5i) have been regarded as an alternative candidate drug for avoiding penile neuropathy. However, the therapeutic efficacy is severely limited due to poor accumulation under systemic medication and endogenous nitric oxide (NO) deficiency in cavernosum. Herein, an innovative liposomal microbubble (MB) loaded with both Sildenafil (one of PDE5i) and NO was designed. Ultrasound-targeted MB destruction (UTMD)-mediated efficient release and integration erectogenic agents into corpus cavernosum with high biosafety. On a bilateral CNI rat model, the multifunctional MB-cooperated UTMD improved microvascular perfusion in penis, simultaneously, alleviated hypoxia and oxidative stress, indicating successful activation of NO-cyclic guanosine monophosphate pathway. Also, evaluation of the endothelial/muscular composition, intracavernosal pressure, and neural integrity in the penis proved that coordinated intervention reversed the abnormal structural remodeling and promoted the recovery of functional erection. Our work demonstrates that MB loading Sildenafil and NO combined with UTMD hold great promise to "awaken" the efficacy of PDE5i in neurogenic ED, which provided a superior option for ensuring penile rehabilitation.

Self-Assembled Peptide Hydrogels in Regenerative Medicine

Regenerative medicine is a complex discipline that is becoming a hot research topic. Skin, bone, and nerve regeneration dominate current treatments in regenerative medicine. A new type of drug is urgently needed for their treatment due to their high vulnerability to damage and weak self-repairing ability. A self-assembled peptide hydrogel is a good scaffolding material in regenerative medicine because it is similar to the cytoplasmic matrix environment; it promotes cell adhesion, migration, proliferation, and division; and its degradation products are natural and harmless proteins. However, fewer studies have examined the specific mechanisms of self-assembled peptide hydrogels in promoting tissue regeneration. This review summarizes the applications and mechanisms of self-assembled short peptide and peptide hydrogels in skin, bone, and neural healing to improve their applications in tissue healing and regeneration.

Advanced hydrogels: New expectation for the repair of organic erectile dysfunction

Organic erectile dysfunction (ED) is a type of sexual disorder in men that is usually associated with illness, surgical injury, normal aging and has a high incidence across the globe. And the essence of penile erection is a neurovascular event regulated by a combination of factors. Nerve and vascular injury are the main causes of erectile dysfunction. Currently, the main treatment options for ED include phosphodiesterase type 5 inhibitors (PDE5Is), intracorporeal injections and vacuum erection devices (VEDs), which are ineffective. Therefore, it is essential to find an emerging, non-invasive and effective treatment for ED. The histopathological damage causing ED can be improved or even reversed with hydrogels, in contrast to current therapies. Hydrogels have many advantages, they can be synthesized from various raw materials with different properties, possess a definite composition, and have good biocompatibility and biodegradability. These advantages make hydrogels an effective drug carrier. In this review, we began with an overview of the underlying mechanisms of organic erectile dysfunction, discussed the dilemmas of existing treatments for ED, and described the unique advantages of hydrogel over other approaches. Then emphasizing the progress of research on hydrogels in the treatment of ED.

Pathway analysis of microarray data from corpora cavernosal tissue of patients with a prostatectomy or Peyronie disease in comparison with a cavernous nerve-injured rat model of erectile dysfunction

INTRODUCTION

Patients with a prostatectomy are at high risk of developing erectile dysfunction (ED) that is refractory to phosphodiesterase type 5 inhibitors. The cavernous nerve (CN) is frequently damaged during prostatectomy, causing loss of innervation to the penis. This initiates corpora cavernosal remodeling (apoptosis and fibrosis) and results in ED.

AIM

To aid in the development of novel ED therapies, the current aim was to obtain a global understanding of how signaling mechanisms alter in the corpora cavernosa with loss of CN innervation that results in ED.

METHODS

Microarray and pathway analysis were performed on the corpora cavernosal tissue of patients with a prostatectomy (n = 3) or Peyronie disease (control, n = 3). Results were compared with an analysis of a Sprague-Dawley rat CN injury model (n = 10). RNA was extracted by TRIzol, DNase treated, and purified by a Qiagen Mini Kit. Microarray was performed with the Human Gene 2.0 ST Array and the RU34 rat array. Differentially expressed genes were identified through several analytic tools (ShinyGO, Ingenuity, WebGestalt) and databases (GO, Reactome). A 2-fold change was used as the threshold for differential expression.

OUTCOMES

Pathways that were altered (up- or downregulated) in response to CN injury in the prostatectomy patients and a rat CN injury model were determined.

RESULTS

Microarray identified 197 differentially expressed protein-coding genes in the corpora cavernosa from the prostatectomy cohort, with 100 genes upregulated and 97 genes downregulated. Altered signaling pathways that were identified that affect tissue morphology included the following: neurologic disease, cell death and survival, tissue and cellular development, skeletal and muscle development and disorders, connective tissue development and function, tissue morphology, embryonic development, growth and proliferation, cell-to-cell signaling, and cell function and maintenance. These human pathways have high similarity to those observed in the CN-injured rat ED model.

CLINICAL IMPLICATIONS

Significant penile remodeling continues in patients long after the acute surgical injury to the CN takes place, offering the opportunity for clinical intervention to reverse penile remodeling and improve erectile function.

STRENGTHS AND LIMITATIONS

Understanding how signaling pathways change in response to CN injury and how these changes translate to altered morphology of the corpora cavernosa and ensuing ED is critical to identify strategic targets for therapy development.

CONCLUSION

Altered signaling in pathways that regulate tissue homeostasis, morphogenesis, and development was identified in penes of patients with a prostatectomy, and competitive forces of apoptosis and proliferation/regeneration were found to compete to establish dominance after CN injury. How these pathways interact to regulate penis tissue homeostasis is a complex process that requires further investigation.

Molecular pathogenesis and treatment of cavernous nerve injury-induced erectile dysfunction: A narrative review

Introduction: Erectile dysfunction (ED) is a common complication after radical prostatectomy (RP), and it seriously affects the quality of life in patients and their partners. The primary trigger of postoperative ED is surgical injury to the cavernous nerves that control penile erection and run along the anterolateral aspect of the prostate. Despite the introduction and ongoing innovation of nerve-sparing techniques, a significant number of patients still suffer from moderate cavernous nerve injury (CNI), which is thought to be transient and reversible. Therefore, early postoperative penile rehabilitation therapy may salvage patients’ erectile function by promoting cavernous nerve regeneration and preventing penile structural alterations.

Aims: To present a comprehensive overview of the current molecular pathogenesis of CNI-induced ED, as well as novel therapeutic strategies and their potential mechanisms.

Methods: A literature search was performed using PubMed. Search terms included erectile dysfunction, cavernous nerve injury, pathogenesis, pathway, and treatment.

Results: The NOS/NO pathway, oxidative stress-related pathway, RhoA/ROCK pathway, transforming growth factor-β (TGF-β), sonic hedgehog (Shh), and hydrogen sulfide (H2S) are involved in the molecular pathogenesis of CNI-induced ED. Multiple neurotrophins, including brain-derived nerve growth factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and neurturin (NTN), were found to promote cavernous nerve regeneration. Emerging therapeutic approaches can be roughly summarized into four categories, namely small molecule and drug, stem cell-based therapy (SCT), micro-energy therapy and platelet-rich plasma (PRP) therapy.

Conclusion: These pathways collectively lead to the irreversible damage to the penile structure after CNI. The combined early rehabilitation strategies of promoting upstream nerve regeneration and recovering abnormal molecular signals of downstream penis are presumed to save patients’ erectile function after RP. In future studies, the cross-talk between these molecular pathways needs to be further clarified, and the questions of how denervation injury induces the molecular alterations in the penis also need to be addressed.

Sonic Hedgehog Signaling in Primary Culture of Human Corpora Cavernosal Tissue From Prostatectomy, Diabetic, and Peyronie's Patients

BACKGROUND

Cavernous nerve (CN) injury causes penile remodeling, including smooth muscle apoptosis and increased collagen, which results in erectile dysfunction (ED), and prevention of this remodeling is critical for novel ED therapy development.

AIM

We developed 2 peptide amphiphile (PA) hydrogel delivery vehicles for Sonic hedgehog (SHH) protein to the penis and CN, which effectively suppress penile distrophic remodeling (apoptosis and fibrosis), in vivo in a rat CN injury model, and the aim of this study is to determine if SHH PA can be used to regenerate human corpora cavernosal smooth muscle deriving from multiple ED origins.

METHODS

Corpora cavernosal tissue was obtained from prostatectomy, diabetic, hypertension, cardiovascular disease and Peyronie's (control) patients (n = 21). Primary cultures (n = 21) were established, and corpora cavernosal cells were treated with SHH protein, MSA (control), 5E1 SHH inhibitor, and PBS (control). Growth was quantified by counting the number of cells at 3-4 days. Statistics were performed by ANOVA with Scheffe's post hoc test. Concentration of SHH protein for maximal growth was optimized, and a more active SHH protein examined.

OUTCOMES

Cultures were characterized by immunohistochemical analysis with ACTA2, CD31, nNOS and P4HB, and smooth muscle was quantified in comparison to DAPI.

RESULTS

Cultures established were >97% smooth muscle. SHH protein increased growth of smooth muscle cells from prostatectomy, diabetic, and Peyronie's patients in a similar manner (49%-51%), and SHH inhibition decreased growth (20%-33%). There was no difference in growth using 25 ug and 10 ug SHH protein, suggesting a threshold concentration of SHH protein above which smooth muscle growth is enhanced. A more active lipid modified SHH peptide further enhanced growth (15%), indicating a more robust growth response. SHH increased growth in smooth muscle cells from hypertension (37%) and cardiovascular disease (32%) patients. SHH protein increased growth under normal and high glucose conditions, suggesting that high glucose conditions that may be present in under controlled diabetic patients would not detract from SHH regenerative capacity.

CLINICAL IMPLICATIONS

SHH PA would be beneficial to enhance smooth muscle regeneration in patients with ED of multiple etiologies.

STRENGTHS AND LIMITATIONS

Understanding how human corpora cavernosal tissue responds to SHH treatment is critical for clinical translation of SHH PA to ED patients.

CONCLUSION

Corpora cavernosal smooth muscle from all ED patients responded to SHH treatment with increased growth. Stupp, SI. Sonic Hedgehog Signaling in Primary Culture of Human Corpora Cavernosal Tissue From Prostatectomy, Diabetic, and Peyronie's Patients. J Sex Med 2022;19:1228-1242.

Nanotechnology as a tool to advance research and treatment of non-oncologic urogenital diseases

Nanotechnology represents an expanding area of research and innovation in almost every field of science, including Medicine, where nanomaterial-based products have been developed for diagnostic and therapeutic applications. Because of their small, nanoscale size, these materials exhibit unique physical and chemical properties that differ from those of each component when considered in bulk. In Nanomedicine, there is an increasing interest in harnessing these unique properties to engineer nanocarriers for the delivery of therapeutic agents. Nano-based drug delivery platforms have many advantages over conventional drug administration routes as this technology allows for local and transdermal applications of therapeutics that can bypass the first-pass metabolism, improves drug efficacy through encapsulation of hydrophobic drugs, and allows for a sustained and controlled release of encapsulated agents. In Urology, nano-based drug delivery platforms have been extensively investigated and implemented for cancer treatment. However, there is also great potential for use of nanotechnology to treat non-oncologic urogenital diseases. We provide an update on research that is paving the way for clinical translation of nanotechnology in the areas of erectile dysfunction (ED), overactive bladder (OAB), interstitial cystitis/bladder pain syndrome (IC/BPS), and catheter-associated urinary tract infections (CAUTIs). Overall, preclinical and clinical studies have proven the utility of nanomaterials both as vehicles for transdermal and intravesical delivery of therapeutic agents and for urinary catheter formulation with antimicrobial agents to treat non-oncologic urogenital diseases. Although clinical translation will be dependent on overcoming regulatory challenges, it is inevitable before there is universal adoption of this technology to treat non-oncologic urogenital diseases.

Photoactuating Artificial Muscles of Motor Amphiphiles as an Extracellular Matrix Mimetic Scaffold for Mesenchymal Stem Cells

Mimicking the native extracellular matrix (ECM) as a cell culture scaffold has long attracted scientists from the perspective of supramolecular chemistry for potential application in regenerative medicine. However, the development of the next-generation synthetic materials that mimic key aspects of ECM, with hierarchically oriented supramolecular structures, which are simultaneously highly dynamic and responsive to external stimuli, remains a major challenge. Herein, we present supramolecular assemblies formed by motor amphiphiles (MAs), which mimic the structural features of the hydrogel nature of the ECM and additionally show intrinsic dynamic behavior that allow amplifying molecular motions to macroscopic muscle-like actuating functions induced by light. The supramolecular assembly (named artificial muscle) provides an attractive approach for developing responsive ECM mimetic scaffolds for human bone marrow-derived mesenchymal stem cells (hBM-MSCs). Detailed investigations on the photoisomerization by nuclear magnetic resonance and UV–vis absorption spectroscopy, assembled structures by electron microscopy, the photoactuation process, structural order by X-ray diffraction, and cytotoxicity are presented. Artificial muscles of MAs provide fast photoactuation in water based on the hierarchically anisotropic supramolecular structures and show no cytotoxicity. Particularly important, artificial muscles of MAs with adhered hBM-MSCs still can be actuated by external light stimulation, showing their ability to convert light energy into mechanical signals in biocompatible systems. As a proof-of-concept demonstration, these results provide the potential for building photoactuating ECM mimetic scaffolds by artificial muscle-like supramolecular assemblies based on MAs and offer opportunities for signal transduction in future biohybrid systems of cells and MAs.

Pathway Enrichment Analysis of Microarray Data Fom Human Penis of Diabetic and Peyronie's Patients, in Comparison with Diabetic Rat Erectile Dysfunction Models

BACKGROUND

Erectile dysfunction (ED) is a debilitating medical condition in which current treatments are minimally effective in diabetic patients due to neuropathy of the cavernous nerve, a peripheral nerve that innervates the penis. Loss of innervation causes apoptosis of penile smooth muscle, remodeling of corpora cavernosa (penile erectile tissue) morphology, and ED.

AIM

In this study, microarray and pathway analysis were used to obtain a global understanding of how signaling mechanisms are altered in diabetic patients and animal models as ED develops, in order to identify novel targets for disease management, and points of intervention for clinical therapy development.

METHODS AND OUTCOMES

Human corpora cavernosal tissue was obtained from diabetic (n = 4) and Peyronie's (control, n = 3) patients that were undergoing prosthesis implant to treat ED, and BB/WOR diabetic (n = 5) and resistant (n = 5) rats. RNA was extracted using TRIzol, DNase treated, and purified by Qiagen mini kit. Microarray was performed using the Human Gene 2.0 ST Array. (i) Alterations in patient and diabetic rat pathway signaling were examined using several analytical tools (ShinyGO, Metascape, WebGestalt, STRING) and databases, (ii) Strengths/weaknesses of the different pathway analysis tools were compared, and (iii) Comparison of human and rat (BB/WOR and Streptozotocin) pathway analysis was performed. Two technical replicates were performed. P value (FDR) < .15 was used as threshold for differential expression. FDR < 0.05 was considered significant.

RESULTS

Microarray identified 182 differentially expressed protein-coding genes. Pathway analysis revealed similar enrichments with different analytical tools. Down regulated pathways include development, tubular structure, sprouting, cell death, ischemia, angiogenesis, transcription, second messengers, and stem cell differentiation. ED patients, who have diabetes, incur significant loss of normal regulatory processes required for repair and replacement of injured corpora cavernosal tissue. Combined with loss of apoptotic regulatory mechanisms, this results in significant architectural remodeling of the corpora cavernosa, and loss of regenerative capacity in the penis.

CLINICAL TRANSLATION

This first report of microarray and pathway analysis in human corpora cavernosa, is critical for identification of novel pathways pertinent to ED and for validating animal models.

STRENGTHS AND LIMITATIONS

The analysis of tissue specific gene expression profiles provides a means of understanding drivers of disease and identifying novel pathways for clinical intervention.

CONCLUSION

Penis from diabetic ED patients lacks capacity for maintenance of corpora cavernosal architecture and regeneration, which are critical points for intervention for therapy development.

Peptide amphiphile nanofiber hydrogel delivery of Sonic hedgehog protein to the penis and cavernous nerve suppresses intrinsic and extrinsic apoptotic signaling mechanisms, which are an underlying cause of erectile dysfunction

Erectile dysfunction (ED) is a common and debilitating condition with high impact on quality of life. An underlying cause of ED is apoptosis of penile smooth muscle, which occurs with cavernous nerve injury, in prostatectomy, diabetic and aging patients. We are developing peptide amphiphile (PA) nanofiber hydrogels as an in vivo delivery vehicle for Sonic hedgehog protein to the penis and cavernous nerve to prevent the apoptotic response. We examine two important aspects required for clinical application of the biomaterials: if SHH PA suppresses intrinsic (caspase 9) and extrinsic (caspase 8) apoptotic mechanisms, and if suppressing one apoptotic mechanism forces apoptosis to occur via a different mechanism. We show that SHH PA suppresses both caspase 9 and 8 apoptotic mechanisms, and suppressing caspase 9 did not shift signaling to caspase 8. SHH PA has significant clinical potential as a preventative ED therapy, by management of intrinsic and extrinsic apoptotic mechanisms.

Functionalized Peptide Fibrils as a Scaffold for Active Substances in Wound Healing

Technological developments in the field of biologically active peptide applications in medicine have increased the need for new methods for peptide delivery. The disadvantage of peptides as drugs is their low biological stability. Recently, great attention has been paid to self-assembling peptides that can form fibrils. Such a formulation makes bioactive peptides more resistant to enzymatic degradation and druggable. Peptide fibrils can be carriers for peptides with interesting biological activities. These features open up prospects for using the peptide fibrils as long-acting drugs and are a valid alternative to conventional peptidic therapies. In our study, we designed new peptide scaffolds that are a hybrid of three interconnected amino acid sequences and are: pro-regenerative, cleavable by neutrophilic elastase, and fibril-forming. We intended to obtain peptides that are stable in the wound environment and that, when applied, would release a biologically active sequence. Our studies showed that the designed hybrid peptides show a high tendency toward regular fibril formation and are able to release the pro-regenerative sequence. Cytotoxicity studies showed that all the designed peptides were safe, did not cause cytotoxic effects and revealed a pro-regenerative potential in human fibroblast and keratinocyte cell lines. In vivo experiments in a dorsal skin injury model in mice indicated that two tested peptides moderately promote tissue repair in their free form. Our research proves that peptide fibrils can be a druggable form and a scaffold for active peptides.

Caspase Signaling in ED Patients and Animal Models

BACKGROUND

Current treatments for erectile dysfunction (ED) are ineffective in prostatectomy and diabetic patients due to cavernous nerve (CN) injury, which causes smooth muscle apoptosis, penile remodeling, and ED. Apoptosis can occur via the intrinsic (caspase 9) or extrinsic (caspase 8) pathway.

AIM

We examined the mechanism of how apoptosis occurs in ED patients and CN injury rat models to determine points of intervention for therapy development.

METHODS AND OUTCOMES

Immunohistochemical and western analyses for caspase 3-cleaved, caspase-8 and caspase-9 (pro and active forms) were performed in corpora cavernosal tissue from Peyronie's, prostatectomy and diabetic ED patients (n = 33), penis from adult Sprague Dawley rats that underwent CN crush (n = 24), BB/WOR diabetic and control rats (n = 8), and aged rats (n = 9).

RESULTS

Caspase 3-cleaved was observed in corpora cavernosa from Peyronie's patients and at higher abundance in prostatectomy and diabetic tissues. Apoptosis takes place primarily through the extrinsic (caspase 8) pathway in penis tissue of ED patients. In the CN crushed rat, caspase 3-cleaved was abundant from 1-9 days after injury, and apoptosis takes place primarily via the intrinsic (caspase 9) pathway. Caspase 9 was first observed and most abundant in a layer under the tunica, and after several days was observed in the lining of and between the sinuses of the corpora cavernosa. Caspase 8 was initially observed at low abundance in the rat corpora cavernosa and was not observed at later time points after CN injury. Aged and diabetic rat penis primarily exhibited intrinsic mechanisms, with diabetic rats also exhibiting mild extrinsic activation.

CLINICAL TRANSLATION

Knowing how and when to intervene to prevent the apoptotic response most effectively is critical for the development of drugs to prevent ED, morphological remodeling of the corpora cavernosa, and thus, disease management.

STRENGTHS AND LIMITATIONS

Animal models may diverge from the signaling mechanisms observed in ED patients. While the rat utilizes primarily caspase 9, there is a significant flux through caspase 8 early on, making it a reasonable model, as long as the timing of apoptosis is considered after CN injury.

CONCLUSIONS

Apoptosis takes place primarily through the extrinsic caspase 8 dependent pathway in ED patients and via the intrinsic caspase 9 dependent pathway in commonly used CN crush ED models. This is an important consideration for study design and interpretation that must be taken into account for therapy development and testing of drugs, and our therapeutic targets should ideally inhibit both apoptotic mechanisms. Martin S, Harrington DA, Ohlander S, et al. Caspase Signaling in ED Patients and Animal Models. J Sex Med 2021;18:711-722.

Self-Assembling Peptides as an Emerging Platform for the Treatment of Metabolic Syndrome

Metabolic syndrome comprises a cluster of comorbidities that represent a major risk of developing chronic diseases, such as type II diabetes, cardiovascular diseases, and stroke. Alarmingly, metabolic syndrome reaches epidemic proportions worldwide. Today, lifestyle changes and multiple drug-based therapies represent the gold standard to address metabolic syndrome. However, such approaches face two major limitations: complicated drug therapeutic regimes, which in most cases could lead to patient incompliance, and limited drug efficacy. This has encouraged scientists to search for novel routes to deal with metabolic syndrome and related diseases. Within such approaches, self-assembled peptide formulations have emerged as a promising alternative for treating metabolic syndrome. In particular, self-assembled peptide hydrogels, either as acellular or cell-load three-dimensional scaffoldings have reached significant relevance in the biomedical field to prevent and restore euglycemia, as well as for controlling cardiovascular diseases and obesity. This has been possible thanks to the physicochemical tunability of peptides, which are developed from a chemical toolbox of versatile amino acids enabling flexibility of designing a wide range of self-assembled/co-assembled nanostructures forming biocompatible viscoelastic hydrogels. Peptide hydrogels can be combined with several biological entities, such as extracellular matrix proteins, drugs or cells, forming functional biologics with therapeutic ability for treatment of metabolic syndrome-comorbidities. Additionally, self-assembly peptides combine safety, tolerability, and effectivity attributes; by this presenting a promising platform for the development of novel pharmaceuticals capable of addressing unmet therapeutic needs for diabetes, cardiovascular disorders and obesity. In this review, recent advances in developing self-assembly peptide nanostructures tailored for improving treatment of metabolic syndrome and related diseases will be discussed from basic research to preclinical research studies. Challenges facing the development of approved medicinal products based on self-assembling peptide nanomaterials will be discussed in light of regulatory requirement for clinical authorization.

Self-assembling Peptides in Current Nanomedicine: Versatile Nanomaterials for Drug Delivery

BACKGROUND

The development of modern nanomedicine greatly depends on the involvement of novel materials as drug delivery system. In order to maximize the therapeutic effects of drugs and minimize their side effects, a number of natural or synthetic materials have been widely investigated for drug delivery. Among these materials, biomimetic self-assembling peptides (SAPs) have received more attention in recent years. Considering the rapidly growing number of SAPs designed for drug delivery, a summary of how SAPs-based drug delivery systems were designed, would be beneficial.

METHOD

We outlined research works on different SAPs that have been investigated as carriers for different drugs, focusing on the design of SAPs nanomaterials and how they were used for drug delivery in different strategies.

RESULTS

Based on the principle rules of chemical complementarity and structural compatibility, SAPs such as ionic self-complementary peptide, peptide amphiphile and surfactant-like peptide could be designed. Determined by the features of peptide materials and the drugs to be delivered, different strategies such as hydrogel embedding, hydrophobic interaction, electrostatic interaction, covalent conjugation or the combination of them could be employed to fabricate SAPs-drug complex, which could achieve slow release, targeted or environment-responsive delivery of drugs. Furthermore, some SAPs could also be combined with other types of materials for drug delivery, or even act as drug by themselves.

CONCLUSION

Various types of SAPs have been designed and used for drug delivery following various strategies, suggesting that SAPs as a category of versatile nanomaterials have promising potential in the field of nanomedicine.

Restoration of Cavernous Veno-Occlusive Function through Chronic Administration of a Jun-Amino Terminal Kinase Inhibitor and a LIM-Kinase 2 Inhibitor by Suppressing Cavernous Apoptosis and Fibrosis in a Rat Model of Cavernous Nerve Injury: A Comparison with a Phosphodiesterase Type 5 Inhibitor

Purpose

To determine if chronic administration of Jun-amino terminal kinase (JNK)-inhibitors and LIM-kinase 2 (LIMK2)-inhibitors from the immediate post-injury period in a rat model of cavernous-nerve-crush-injury could normalize cavernous-veno-occlusive-function, and to compare it with phosphodiesterase type 5 (PDE5)-inhibitors.

Materials and Methods

A total of 75 12-week-old male Sprague–Dawley-rats were randomized into five groups: sham-surgery (S), cavernous-nerve-crush-injury (I), cavernous-nerve-crush-injury treated with 10.0 mg/kg LIMK2-inhibitor (L) or 10.0 mg/kg JNK-inhibitor and 10.0 mg/kg LIMK2-inhibitor (J+L) or 20.0 mg/kg udenafil (P) for five-weeks. Five-weeks after surgery, dynamic-infusion-cavernosometry, histological-studies, caspase-3-activity-assay, and Western-blot were investigated.

Results

Group-I had lower papaverine-response, higher maintenance-rate and higher drop-rate, compared to Group-S. Group-L, Group-J+L and Group-P showed improvement in the three dynamic-infusion-cavernosometry parameters. The papaverine-response and drop-rate in Group-J+L and Group-P recovered to sham-control level, but those in Group-L did not. Regarding apoptosis, Group-I had decreased content of α-smooth-muscle-actin, increased caspase-3 activity and increased cJun-phosphorylation. The cJun-phosphorylation improved only in Group-J+L. The α-smooth-muscle-actin content and caspase-3-activity in Group-J+L and Group-P improved, but those in Group-L were not. Regarding fibrosis, Group-I had decreased smooth muscle (SM)/collagen-ratio, increased protein-expression of fibronectin, and increased Cofilin-phosphorylation. Cofilin-phosphorylation was normalized in Group-L and Group-J+L, but not in Group-P. SM/collagen-ratio and protein-expression of fibronectin in Group-L, Group-J+L and Group-P improved.

Conclusions

Our data indicate that chronic inhibition of JNK and LIMK2 can restore cavernous-veno-occlusive-function by suppressing cavernous-apoptosis and cavernous-fibrosis, comparable to the results by PDE5-inhibitors. Chronic inhibition of JNK and LIMK2 might be a potential mechanism-specific targeted therapy for cavernous-veno-occlusive-dysfunction induced by cavernous nerve-injury.

Simvastatin alleviated diabetes mellitus-induced erectile dysfunction in rats by enhancing AMPK pathway-induced autophagy

BACKGROUND

Diabetes mellitus-induced erectile dysfunction is a common diabetic complication, and new therapeutics and the pathogenesis of diabetes mellitus-induced erectile dysfunction need to be investigated.

OBJECTIVES

The aim was to investigate the pathogenesis of diabetes mellitus-induced erectile dysfunction and the pharmacological mechanism of simvastatin treatment in diabetes mellitus-induced erectile dysfunction model rats.

MATERIALS AND METHODS

A total of 86 male Sprague Dawley rats aged 8 weeks old were used in this study. The rats were divided into three groups: control (normal), diabetes mellitus-induced erectile dysfunction (streptozotocin-injected), and diabetes mellitus-induced erectile dysfunction + simvastatin (sim). Each group was subdivided into two subgroups for in vitro and in vivo analyses. A bioinformatics method was used to detect differences in gene expression in the corpus cavernosum between normal and diabetes mellitus-induced erectile dysfunction rats. Erectile function was measured by a cavernous nerve electrostimulation test. Corpus cavernosum fibrosis was assessed by Masson staining and Western blotting. Immunofluorescence and Western blotting were performed to explore the differential expression of autophagy-related genes and the AMPK-SKP2-CARM1 pathway genes in rat cavernous smooth muscle cells and the corpus cavernosum. The autophagosomes of the corpus cavernosum tissue were observed by transmission electron microscopy.

RESULTS

Autophagy-related genes and pathways (the AMPK and FoxO pathway) were identified by bioinformatics analysis and confirmed at the protein level. Simvastatin, an AMPK agonist, was used to treat diabetes mellitus-induced erectile dysfunction rats for 8 weeks, demonstrating that erectile function was improved for 80.5% (P < .05) of rats. Corpus cavernosum fibrosis was alleviated (P < .05), and autophagy was further enhanced (P < .05); these results might be partially caused by AMPK-SKP2-CARM1 pathway activation (P < .05).

DISCUSSION AND CONCLUSION

Simvastatin could enhance protective autophagy by activating the AMPK-SKP2-CARM1 pathway to improve erectile function in diabetes mellitus-induced erectile dysfunction rats.

Co-overexpression of VEGF and GDNF in adipose-derived stem cells optimizes therapeutic effect in neurogenic erectile dysfunction model

Objectives

To evaluate the rapid repair potential of adipose‐derived stem cells (ADSCs) co‐overexpressing VEGF and GDNF on bilateral cavernous nerve injury (BCNI) in rat models. Progressive fibrosis of the penis that occurs shortly after BCNI is a key cause of clinical treatment difficulty of erectile dysfunction (ED). Traditional medications are ineffective for ED caused by BCNI. ADSCs have shown therapeutic effects in animal models, but disappointing in clinical treatment suggests that we should explore optimal treatment of it.

Materials and methods

We extracted ADSCs from rat epididymis. Lentiviral transfection was verified by western blot and immunofluorescence. Thirty‐six SD rats (10 weeks old) were randomly divided into six groups (n = 6 per group): sham surgery, and remaining five BCNI groups transplanted PBS or ADSCs which were genetically modified by vehicle, VEGF (ADSC‐V), GDNF (ADSC‐G), or VEGF&GDNF (ADSC‐G&V) around major pelvic ganglion (MPG). We investigated the therapeutic effects of BCNI rat model which is characterized by ED, penile tissue fibrosis and hypoxia, and lack of nitrogen nerves or vascular atrophy.

Results

Erectile function was almost recovered after 2 weeks of transplantation of ADSC‐G&V, promoted cavernous nerve repair, prevented penile fibrosis and preserving the vascular endothelium, which was significant differences amongst ADSC‐V or ADSC‐G. Moreover, GM‐ADSCs were detected in MPG and penis, indicating that their participation in repair of target organs and transverse nerves.

Conclusions

These promising data indicate that ADSCs co‐overexpressed VEGF and GDNF‐induced synergistic effects, make it a potential tool for recovering of erectile function speedily after BCNI.

Overexpression of anti-fibrotic factors ameliorates anti-fibrotic properties of Wharton's jelly derived mesenchymal stem cells under oxidative damage

Transplantation with Wharton's jelly derived mesenchymal stem cells (WJ-MSCs) showed great benefits for restoring myocardial function. However, the outcome of WJ-MSCs transplantation was unsuccessful due to multiple factors including oxidative damage. The presence of oxidative stress due to myocardium injury influences fibrous tissue formation, which causes disability of cardiac muscle. Hepatocyte growth factor (HGF), insulin-like growth factor (IGF1), and sonic hedgehog (SHH) are well-known master regulators in anti-fibrosis when secreted by WJ-MSCs. They showed a beneficial role in the recovery of cardiac fibrosis after WJ-MSCs transplantation. This study hypothesizes whether the reduction of the anti-fibrosis property in WJ-MSCs from oxidative damage can be recovered by overexpression of the HGF, IGF1, or SHH gene. Overexpression was attained by transfection of WJ-MSCs with pCMV3-HGF, pCMV3-IGF1, or pCMV3-SHH followed by H2O2 exposure and co-culturing with cardiac fibroblasts. Myofibroblast specific markers comprised of alpha-smooth muscle actin (α-SMA) and collagen type 1 (COL1) were evaluated. The WJ-MSCs treated with H2O2 influenced the expression of myofibroblastic markers, whereas the overexpression of HGF, IGF1 or SHH reduced myofibroblastic formation. These results indicate that the oxidative stress impaired anti-fibrotic property of WJ-MSCs, leads to an increase of myofibroblasts. Overexpression of anti-fibrotic genes restored the endogenous HGF, IGF1, and SHH alleviating improvement of cardiac function.

Combination of LIM-kinase 2 and Jun Amino-terminal Kinase Inhibitors Improves Erectile Function in a Rat Model of Cavernous Nerve Injury

OBJECTIVE

To determine if combined administration of LIMK2 and JNK inhibitors in a rat model of erectile dysfunction induced by cavernosal nerve (CN) injury could restore erectile function by suppressing both cavernosal apoptosis and fibrosis via rectification of molecular pathways related to the structural alterations.

METHODS

Sixty 12-week-old male Sprague-Dawley rats were categorized into 4 groups: (1) Sham-surgery (Sham) group, (2) CN-crush-injury (CNCI), (3) CNCI group (CNCI+L+1.0J) treated with a combination of 10.0 mg/kg LIMK2-inhibitors and low-dose (1.0 mg/kg) JNK-inhibitors, and (4) CNCI group (CNCI+L+10.0J) treated with a combination of 10.0 mg/kg LIMK2-inhibitors and a high dose (10.0 mg/kg) of JNK-inhibitors. Ten days after surgery, erectile response, histological-studies, and Western-blot was investigated.

RESULTS

The CNCI group showed a reduced maximal ICP/MAP or AUC/MAP, decreased immunohistochemical-staining of α-SMA, decreased SM/collagen ratio, increased phospho-cJun-positive apoptotic cells, increased phospho-LIMK2-positive fibroblasts, increased cJun-phosphorylation, increased LIMK2/Cofilin-phosphorylation, decreased Bcl-2/Bax ratio, and increased protein-expression of fibronectin, compared to the Sham group. Both the CNCI+L+1.0J and CNCI+L+10.0J groups showed improvements in erectile-responses, content of cavernosal α-SMA, number of phospho-cJun-positive apoptotic cells, Bcl-2/Bax ratio and cJun phosphorylation. Their improvements in the CNCI+L+10.0J group showed a tendency to be greater than those in the CNCI+L+1.0J group. Also, in the 2 treatment groups, rectification of SM/collagen ratio, number of phospho-LIMK2-positive fibroblasts, LIMK2/Cofilin-phosphorylation, and protein-expression of fibronectin was observed.

CONCLUSION

This study suggests that combined inhibition of JNK and LIMK2 may improve erectile function by suppressing cavernosal apoptosis and fibrosis via restoration of cJun/Bcl-2/Bax and LIMK2/Cofilin pathways at 10 days after CN injury.

Optimization of Sonic Hedgehog Delivery to the Penis from Self-Assembling Nanofiber Hydrogels to Preserve Penile Morphology after Cavernous Nerve Injury

Erectile dysfunction (ED) is a significant medical condition, with high impact on patient quality of life. Current treatments are minimally effective in prostatectomy, diabetic and aging patients due to injury to the cavernous nerve (CN); loss of innervation causes extensive smooth muscle (SM) apoptosis, increased collagen and ED. Sonic hedgehog (SHH) is a critical regulator of penile SM. We developed a self-assembling peptide amphiphile (PA) nanofiber hydrogel for extended release of SHH protein to the penis after CN injury, to suppress SM apoptosis. In this study we optimize the animal model, SHH concentration, duration of suppression, and location of delivery, to maximize SM preservation. SHH treatment suppressed apoptosis and preserved SM 48%. Increased SHH duration preserved SM 100%. Simultaneous penis/CN delivery increased SM 127%. Optimization of SHH PA delivery is essential for clinical translation to ED patients, and the PA vehicle has wide applicability as an in vivo delivery tool.

Sonic hedgehog regulation of cavernous nerve regeneration and neurite formation in aged pelvic plexus

INTRODUCTION

Erectile dysfunction (ED) is a significant health concern that greatly impacts quality of life, and is common in men as they age, impacting 52% of men between the ages of 40 and 70. A significant underlying cause of ED development is injury to the cavernous nerve (CN), a peripheral nerve that innervates the penis. CN injury also occurs in up to 82% of prostatectomy patients. We recently showed that Sonic hedgehog (SHH) protein delivered by peptide amphiphile (PA) nanofiber hydrogel to the CN and penis of a prostatectomy model of CN injury, is neuroprotective, accelerates CN regeneration, improves erectile function ~60%, preserves penile smooth muscle 56% and suppresses collagen deposition 30%. This regenerative potential is substantial in an adult prostatectomy model (P120). However prostatectomy patients are typically older (61.5 ± 9.6 years) and our models should mimic patient conditions more effectively when considering translation. In this study we examine regenerative potential in an aged prostatectomy model (P200-329).

METHODS

The caudal portion of the pelvic ganglia (MPG) and CN were dissected from adult (n = 11), and aged (n = 13) Sprague Dawley rats, and were grown in organ culture 3 days. Uninjured and 2 day CN crushed MPG/CN were exposed to Affi-Gel beads containing SHH protein, PBS (control), or 5e1 SHH inhibitor. Neurites were quantified by counting the number of growth cones normalized by tissue perimeter (mm) and immunohistochemistry for SHH, patched1 (PTCH1), smoothened (SMO), GLI1-3, and GAP43 were performed.

RESULTS

SHH treatment increased neurites 3.5-fold, in uninjured adult, and 5.7-fold in aged rats. Two days after CN crush, SHH treatment increased neurites 1.8-fold in adult rats and 2.5-fold in aged rats. SHH inhibition inhibited neurite formation in uninjured MPG/CN but not in 2 day CN crushed MPG/CN. PTCH1 and SMO (SHH receptors), and SHH transcriptional activators/repressors, GLI1-3, were abundant in aged MPG/CN with unaltered localization. ROCK1 was induced with SHH treatment.

CONCLUSIONS

Reintroduction of SHH protein in an aged prostatectomy model is even more effective in promoting neurite formation/CN regeneration than in the adult. The first 48 h after CN injury are a critical window when growth factors are released, that impact later neurite formation. These studies are significant because most prostatectomy patients are not young and healthy, as with adult rats, so the aged prostatectomy model will more accurately simulate ED patient response. Understanding how neurite formation changes with age is critical for clinical translation of SHH PA to prostatectomy patients.

Peptide supramolecular materials for therapeutics

Supramolecular assembly of peptide-based monomers into nanostructures offers many promising applications in advanced therapies. In this Tutorial Review, we introduce molecular designs to control the structure and potential biological function of supramolecular assemblies. An emphasis is placed on peptide-based supramolecular nanostructures that are intentionally designed to signal cells, either directly through the incorporation of amino acid sequences that activate receptors or indirectly by recruiting native signals such as growth factors. Additionally, we describe the use and future potential of hierarchical structures, such as single molecules that assemble into nanoscale fibers which then align to form macroscopic strings; the strings can then serve as scaffolds for cell growth, proliferation, and differentiation.

Cavernosopatía traumática crónica. Un nuevo síndrome de fibrosis peneana

Introdución La llamada genéricamente «enfermedad de Peyronie» es un diagnóstico que explica un porcentaje de ciertos estados de fibrosis peneana grave, pero se queda corta para abarcar la amplia gama de grises de la fibrosis peneana secundaria a microtrauma sexual repetido.

Objectivo Describir un nuevo síndrome por trauma repetido en el pene al que se propone denominar «cavernosopatía traumática crónica» (CTC), con 4 componentes: fibrosis (leve, moderada o grave), disfunción eréctil, curvatura y fugas venosas peneanas.

Materiales y métodos Se realizó un estudio de corte transversal en una base de datos de 128 pacientes que tenían al menos una ecografía de pene con vasoactivo y en los que se había detectado algún grado de fibrosis cavernosa según la clasificación de Levine. Se evaluó la presencia de disfunción eréctil, curvas y fugas venosas según el grado de fibrosis. El estudio contó con la aprobación del Comité de Ética en Investigación.

Resultados Se estudió a 128 pacientes con fibrosis, con 51,3 años de edad promedio (DE = 13). El grado de fibrosis fue leve (Levine 1) en 30 (23,43%), moderado (Levine 2) en 23 (17,96%) y grave (Levine 3) en 75 (58,6%). Se demostró que, a mayor fibrosis, mayor disfunción eréctil, 66,6; 83,6 y 96% para Levine 1, 2 y 3, respectivamente (p ≤ 0,0001). La frecuencia de curvatura secundaria (n = 71) fue de 0; 4,2 y 95,7% para Levine 1, 2 y 3, respectivamente (p ≤ 0,0001). La frecuencia en los 44 pacientes con fugas cavernosas fue de 9; 20,4 y 70,4% (p = 0,0060) y en los 15 de fugas dorsales fue de 80; 13,3 y 6,6% (p < 0,0001) para Levine 1, 2 y 3 respectivamente. El grupo de 79 pacientes (64,03%) con mayor posibilidad de CTC, con presencia de 3 o 4 criterios que incluyeran curvatura secundaria y fuga cavernosa, tuvo un promedio de edad de 59,2 años (DE = 8,7), comparado con 41,7 años (DE = 11,7) en el grupo de menor posibilidad, diferencia estadísticamente significativa (p ≤ 0,0001).

Conclusiones Proponemos que existe un síndrome de microtrauma repetido en el pene, que puede denominarse CTC, análogo a la encefalopatía traumática crónica, con 4 componentes: fibrosis cavernosa, disfunción eréctil, curvatura peneana y fugas venosas. La fibrosis es un continuum que el paciente recorre por fases leves y moderadas, a menudo inapreciables para los clínicos. Las curvaturas secundarias y las fugas cavernosas están relacionadas directamente con el grado de fibrosis y con mayor riesgo de disfunción eréctil. La edad empeora algunos factores de la CTC.

Progress Toward the Clinical Translation of Bioinspired Peptide and Protein Assemblies

Supramolecular materials composed of proteins and peptides have been receiving considerable attention toward a range of diseases and conditions from vaccines to drug delivery. Owing to the relative newness of this class of materials, the bulk of work to date has been preclinical. However, examples of approved treatments particularly in vaccines, dentistry, and hemostasis demonstrate the translational potential of supramolecular polypeptides. Critical milestones in the clinical development of this class of materials and currently approved supramolecular polypeptide therapies are described in this study. Additional examples of not-yet-approved materials that are steadily advancing toward clinical use are also featured. Spherical assemblies such as virus-like particles, designed protein nanoparticles, and spherical peptide amphiphiles are highlighted, followed by fiber-forming systems such as fibrillizing peptides, fiber-forming peptide-amphiphiles, and filamentous bacteriophages.

Balancing hydrophobicity and sequence pattern to influence self-assembly of amphipathic peptides

Amphipathic peptides with alternating polar and nonpolar amino acid sequences efficiently self-assemble into functional β-sheet fibrils as long as the nonpolar residues have sufficient hydrophobicity. For example, the Ac-(FKFE)2 -NH2 peptide rapidly self-assembles into β-sheet bilayer nanoribbons, while Ac-(AKAE)2 -NH2 fails to self-assemble under similar conditions due to the significantly reduced hydrophobicity and β-sheet propensity of Ala relative to Phe. Herein, we systematically explore the effect of substituting only two of the four Ala residues at various positions in the Ac-(AKAE)2 -NH2 peptide with amino acids of increasing hydrophobicity, β-sheet potential, and surface area (including Phe, 1-naphthylalanine (1-Nal), 2-naphthylalanine (2-Nal), cyclohexylalanine (Cha), and pentafluorophenylalanine (F5 -Phe)) on the self-assembly propensity of the resulting sequences. It was found that double Phe variants, regardless of the position of substitution, failed to self-assemble under the conditions used in this study. In contrast, all double 1-Nal and 2-Nal variants readily self-assembled, albeit at differing rates depending on the substitution patterns. To determine whether this was due to hydrophobicity or side chain surface area, we also prepared double Cha and F5 -Phe variant peptides (both side chain groups are more hydrophobic than Phe). Each of these variants also underwent effective self-assembly, with the aromatic F5 -Phe peptides doing so with greater efficiency. These findings provide insight into the role of amino acid hydrophobicity and sequence pattern on self-assembly proclivity of amphipathic peptides and on how targeted substitutions of nonpolar residues in these sequences can be exploited to tune the characteristics of the resulting self-assembled materials.

Peptide-based ambidextrous bifunctional gelator: applications in oil spill recovery and removal of toxic organic dyes for waste water management

A low molecular weight peptide-based ambidextrous gelator molecule has been discovered for efficient control of water pollution. The gelator molecules can gel various organic solvents with diverse polarity, e.g. n-hexane, n-octane, petroleum ether, petrol, diesel, aromatic solvents like chlorobenzene, toluene, benzene, o-xylene and even aqueous phosphate buffer of pH 7.5. These gels have been thoroughly characterized using various techniques including field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction analysis, small angle X-ray scattering and rheological experiments. Interestingly, hydrogel obtained from the gelator molecule has been found to absorb toxic organic dyes (both cationic and anionic dyes) from dye-contaminated water. The gelator molecule can be reused for several cycles, indicating its possible future use in waste water management. Moreover, this gelator can selectively gel petrol, diesel, pump oil from an oil-water mixture in the presence of a carrier solvent, ethyl acetate, suggesting its efficient application for oil spill recovery. These results indicate that the peptide-based ambidextrous gelator produces soft materials (gels) with dual function: (i) removal of toxic organic dyes in waste water treatment and (ii) oil spill recovery.

Neuroprotective and Nerve Regenerative Approaches for Treatment of Erectile Dysfunction after Cavernous Nerve Injury

Erectile dysfunction (ED) is a significant cause of reduced quality of life in men and their partners. Cavernous nerve injury (CNI) during pelvic surgery results in ED in greater than 50% of patients, regardless of additional patient factors. ED related to CNI is difficult to treat and typically poorly responsive to first- and second-line therapeutic options. Recently, a significant amount of research has been devoted to exploring neuroprotective and neuroregenerative approaches to salvage erectile function in patients with CNI. In addition, therapeutic options such as neuregulins, immunophilin ligands, gene therapy, stem cell therapy and novel surgical strategies, have shown benefit in pre-clinical, and limited clinical studies. In the era of personalized medicine, these new therapeutic technologies will be the future of ED treatment and are described in this review.

Role of Nanotechnology in Erectile Dysfunction Treatment

INTRODUCTION

The biological importance of nanotechnology-based delivery vehicles for in vivo tissue regeneration is gaining acceptance by the medical community; however, its relevance and incorporation into the treatment of sexual dysfunction are evolving and have not been well evaluated.

AIM

To provide scientific evidence examining the use of state-of-the-art nanotechnology-based delivery methodology in the treatment of erectile dysfunction (ED) in animal models and in patients.

METHODS

This review assessed the current basic science literature examining the role of nanotechnology-based delivery vehicles in the development of potential ED therapies.

RESULTS

There are four primary areas where nanotechnology has been applied for ED treatment: (i) topical delivery of drugs for on-demand erectile function, (ii) injectable gels into the penis to prevent morphologic changes after prostatectomy, (iii) hydrogels to promote cavernous nerve regeneration or neuroprotection, and (iv) encapsulation of drugs to increase erectile function (primarily of phosphodiesterase type 5 inhibitors).

CONCLUSION

Basic science studies provide evidence for a significant and evolving role for nanotechnology in the development of therapies for ED and suggest that properly administered nano-based therapies might be advantageous for treating male sexual dysfunction.

Self-assembling peptide-based building blocks in medical applications

Peptides and peptide-conjugates, comprising natural and synthetic building blocks, are an increasingly popular class of biomaterials. Self-assembled nanostructures based on peptides and peptide-conjugates offer advantages such as precise selectivity and multifunctionality that can address challenges and limitations in the clinic. In this review article, we discuss recent developments in the design and self-assembly of various nanomaterials based on peptides and peptide-conjugates for medical applications, and categorize them into two themes based on the driving forces of molecular self-assembly. First, we present the self-assembled nanostructures driven by the supramolecular interactions between the peptides, with or without the presence of conjugates. The studies where nanoassembly is driven by the interactions between the conjugates of peptide-conjugates are then presented. Particular emphasis is given to in vivo studies focusing on therapeutics, diagnostics, immune modulation and regenerative medicine. Finally, challenges and future perspectives are presented.

Peptide amphiphile nanofiber hydrogel delivery of sonic hedgehog protein to the cavernous nerve to promote regeneration and prevent erectile dysfunction

Erectile dysfunction (ED) has high impact on quality of life in prostatectomy, diabetic and aging patients. An underlying mechanism is cavernous nerve (CN) injury, which causes ED in up to 80% of prostatectomy patients. We examine how sonic hedgehog (SHH) treatment with innovative peptide amphiphile nanofiber hydrogels (PA), promotes CN regeneration after injury. SHH and its receptors patched (PTCH1) and smoothened (SMO) are localized in PG neurons and glia. SMO undergoes anterograde transport to signal to downstream targets. With crush injury, PG neurons degenerate and undergo apoptosis. SHH protein decreases, SMO localization changes to the neuronal cell surface, and anterograde transport stops. With SHH treatment SHH is taken up at the injury site and undergoes retrograde transport to PG neurons, allowing SMO transport to occur, and neurons remain intact. SHH treatment prevents neuronal degeneration, maintains neuronal, glial and downstream target signaling, and is significant as a regenerative therapy.

Peptide-Based Supramolecular Hydrogels for Delivery of Biologics

The demand for therapeutic biologics has rapidly grown over recent decades, creating a dramatic shift in the pharmaceutical industry from small molecule drugs to biological macromolecular therapeutics. As a result of their large size and innate instability, the systemic, topical, and local delivery of biologic drugs remains a highly challenging task. Although there exist many types of delivery vehicles, peptides and peptide conjugates have received continuously increasing interest as molecular blocks to create a great diversity of supramolecular nanostructures and hydrogels for the effective delivery of biologics, due to their inherent biocompatibility, tunable biodegradability, and responsiveness to various biological stimuli. In this context, we discuss the design principles of supramolecular hydrogels using small molecule peptides and peptide conjugates as molecular building units, and review the recent effort in using these materials for protein delivery and gene delivery.