Smooth Muscle Progenitor Cells Preserve the Erectile Function by Reducing Corporal Smooth Muscle Cell Apoptosis after Bilateral Cavernous Nerve Crush Injury in Rats

Effects of platelet-rich plasma glue placement at the prostatectomy site on erectile function restoration and cavernous nerve preservation in a nerve-sparing prostatectomy rat model

BACKGROUND

Despite the widespread use of nerve-sparing prostatectomy techniques, the incidence of post-operative erectile dysfunction (ED) remains high. Early intracavernous (IC) injection of platelet-rich plasma (PRP) after nerve crushing improves erectile function (EF) in rats by promoting cavernous nerve (CN) regeneration and preventing structural changes in the corpus cavernosum. However, the neuroprotective effects of the in situ application of PRP glue in rats after CN-sparing prostatectomy (CNSP) remain unclear.

AIM

This study aimed to investigate the effects of PRP glue treatment on EF and CN preservation in rats after CNSP.

METHODS

After prostatectomy, male Sprague-Dawley rats were treated with PRP glue, IC PRP injection, or their combination. The intracavernous pressure (ICP), mean arterial pressure (MAP), and CN preservation status in the rats were evaluated after 4 weeks. Results were corroborated using histology, immunofluorescence, and transmission electron microscopy.

RESULTS

The PRP glue-treated rats showed 100% CN preservation and significantly higher ICP responses (the ratio of maximum ICP to MAP (0.79 ± 0.09)) than the CNSP rats (the ratio of maximum ICP to MAP (0.33 ± 0.04)). PRP glue also significantly increased neurofilament-1 expression, indicating its positive effect on the CNs. Furthermore, this treatment significantly increased the expression of α-smooth muscle actin. Electron micrographs revealed that PRP glue preserved the myelinated axons and prevented atrophy of the corporal smooth muscle by maintaining the adherens junctions.

CONCLUSIONS

These results indicate that PRP glue is a potential solution for EF preservation by neuroprotection in patients with prostate cancer who are likely to undergo nerve-sparing radical prostatectomy.

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.

Is there a role for stem cell therapy in erectile dysfunction secondary to cavernous nerve injury? Network meta-analysis from animal studies and human trials

Introduction:

We carried out systematic review and network meta-analysis to investigate the role of stem cell therapy (SCT) in the management of erectile dysfunction (ED) secondary to cavernous nerve injury in rats and post-radical prostatectomy (RP) in humans.

Patients and Methods:

The protocol was registered with PROSPERO database. We searched studies analyzing the efficacy of SCT for ED due to bilateral cavernous nerve injury (BCNI) in rats using Healthcare Databases Advanced Search (HDAS) Export software (MEDLINE, EMBASE, Scopus) from inception to September 2020. The outcome measurements, for 29 animal studies, were intracavernosal pressure (ICP), ICP/MAP (mean arterial pressure) ratio, and histological/molecular changes. All three available human trials evaluating SCT in post-RP ED were assessed for International Index for Erectile Function (IIEF) Score and Erection Hardness Score (EHS).

Results:

For ICP measurement, animal studies were divided into adipose-derived stem cells (ADSCs) subgroup and bone marrow–derived stem cells (BMSCs) subgroup. Pooled analysis of these studies showed a beneficial effect of SCT in improving erectile function in rats with BCNI using network meta-analysis (95% confidence interval, CI; p < 0.001). There was an increase in ICP/MAP ratio in stem cell groups (including co-intervention) compared with control BCNI group. Histological and molecular evaluation of penile tissue revealed an increase in neuronal nitric oxide synthase (nNOS), smooth muscle content, and anti-apoptotic activity. Human trials revealed improved IIEF (70–150% from baseline at 6 months) and EHS (80–200% from baseline).

Conclusion:

Our results confirm that SCT does improve the erectile function in rats having cavernous nerve injury. Similarly, early human results have shown promising results.

PROSPERO registration ID:

CRD42020201343.

Intracavernous Injection of Platelet-Rich Plasma Therapy Enhances Erectile Function and Decreases the Mortality Rate in Streptozotocin-Induced Diabetic Rats

Erectile dysfunction (ED) is an agonizing complication of diabetes mellitus (DM) and it is challenging to treat ED in DM patients. Platelet-rich plasma (PRP) is a unique therapeutic strategy comprising intrinsic growth factors. An attempt was made to explore the potentiality of the PRP treatment in DM-induced ED rats in various groups (control, DM-non-ED, DM-ED, and DM-ED treated with PRP). Streptozotocin (STZ) was used to induce DM in rats. The blood glucose levels of the DM rats were maintained at >300 mg/dl. In the 18-week experiment, survival rate, body weight, intracavernous pressure (ICP) variations, and arterial blood pressure were analyzed. The tissue restoration results were validated by histological, immunofluorescence, and transmission electron microscopic analysis. PRP treatment of DM-ED rats significantly increased all parameters of erectile function compared to pre-treatment of PRP and DM-ED treated with vehicle. The histological results revealed that PRP treatment substantially enhanced the regeneration of myelinated nerves and decreased the atrophy of corporal smooth muscle. Notably, the PRP treatment immensely enhanced the survival rate in post-surgery DM-ED rats. These results indicated certain benefits of PRP treatment in delaying damage and preventing post-surgery complications in DM patients. Hence, PRP treatment is a novel multifactorial strategy for DM-ED patients.

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.

Dual effect of chitosan activated platelet rich plasma (cPRP) improved erectile function after cavernous nerve injury

BACKGROUND

The intracavernosal (IC) injection of chitosan activated platelet rich plasma (cPRP) has shown to improve the erectile dysfunction in cavernous nerve injury rat model. However, the action target of PRP in improving neurogenic erectile dysfunction remains unclear. We aimed to determine the effect of cPRP action at early stage that further mediates its effect on erectile function (EF) recovery in the bilateral cavernous nerve crushing (BCNC) injury rat model.

METHODS

Fifty-four rats were randomly divided into two equal groups: intracavernosal ( IC) injection of saline after BCNC (group 1) and IC injection of cPRP after BCNC (group 2). Five animals in each group were euthanized at 3, 7 and 14 day (d) post-injection, and the tissues were harvested to conduct transmission electron microscopy and histological assays. Six animals in each group were used to determine the recovery of EF at 14 and 28 d post-injury.

RESULTS

IC injections of cPRP increased all EF parameters at 28 d and 14 d post-injury (p < 0.05). cPRP injections simultaneously prevented the loss of neuronal nitric oxide synthase-positive neurons (p < 0.05) and nerve fibers (p < 0.05) in the major pelvic ganglion and cavernous nerve (CN), respectively, compared with saline injections. This simultaneous accelerated the regeneration of myelinated axons of the CN, reduced apoptosis, and enhanced the proliferation of the corporal smooth muscle cells at an earlier stage.

CONCLUSION

These results suggest that the application of cPRP was beneficial to restore EF via neuroprotective and tissue-protective effects at early stage.