Therapeutic Effect of Controlled Release of Dual Growth Factor Using Heparin-Pluronic Hydrogel/Gelatin-Poly (Ethylene Glycol)-Tyramine Hydrogel System in a Rat Model of Cavernous Nerve Injury

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.

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.

Facile Synthesis of In Situ Formable Alginate Composite Hydrogels with Ca2+-Induced Healing Ability

Dental caries have plagued humans for many years. At present, photocrosslinking resin is commonly used in clinics to repair narrow tooth defects, but the ultraviolet light used in this process has unavoidable cytotoxicity. In situ hydrogels with a similar structure to that of the natural extracellular matrix have gradually attracted attention in the field of hard tissue repair engineering. The injectable molding properties of hydrogel also give it the potential to fill irregularly shaped or fine tissue defects. Through a rapid and facile Michael addition reaction, we prepared maleic chitosan (CS-maleic anhydride [MA]) and thiolated alginate (sodium alginate [SA]-SH) to form a CS-MA/SA-SH hydrogel. To endue its mineralize ability, β-glycerophosphate calcium phosphate and calcium carbonate as the precursor of hydroxyapatite (HAp) were premixed in the hydrogel at certain ratios. This kind of hydrogel can quickly form into different shapes within 10 min. It is worth noting that external Ca²⁺ can react with the residual carboxyl groups of SA and provide the hydrogel with a self-healing ability. At the same time, we creatively propose a method that uses alkaline phosphatase to promote the mineralization of HAp in hydrogels, to achieve the purpose of regenerating hard tissue in situ. By examining the properties of hydrogels at different concentrations of calcium and phosphorus salts, we find that the CS-MA/SA-SH hydrogel with 50% (wt.%) inorganic matter presented the best self-healing properties, excellent mineralization of highly crystallized Hap, and has ideal cell compatibility. The potential application of the CS-MA/SA-SH hydrogel in repairing exposed dentin tubules in decayed teeth was explored through preliminary in vitro dental restoration experiments. Obviously, the penetration depth through dentin tubules was better than that of commercial dental sensitizers. In addition, the HAp morphology was affected by the local environment. We believe that this hydrogel can utilize tissues for dental regeneration and mineralization, and the healing ability provides the hydrogel flexibility for further application in hard tissue regeneration.

[Exogenous hydrogen sulfide improves erectile dysfunction by inhibiting apoptosis of corpus cavernosum smooth muscle cells in rats with cavernous nerve injury]

OBJECTIVE

To explore the effects of exogenous hydrogen sulfide (H2S) on apoptosis of corpus cavernosum smooth muscle cells (CCSMCs) and erectile dysfunction (ED) in rats with bilateral cavernous nerve injury (BCNI).

METHODS

Twentyfour male SD rats were randomly divided into 3 groups (n=8):sham operation group, bilateral cavernous nerve injury group (BCNI group) and H2S intervention group (BCNI+NaHS group). In BCNI and BCNI+NaHS groups, BCNI was induced by clamp injury of the bilateral cavernous nerves, and the rats were subjected to daily intraperitoneal injection of normal saline and 100 μmol/kg NaHS solution for 4 weeks, respectively. After the treatment, the intracavernous pressure (ICP) and mean arterial pressure (MAP), ) of the rats were measured. Western blotting was used to detect the expressions of cystathionine β synthetase (CBS), cystathionine γ lyase (CSE), α-SMA, collagen-I, caspase-3, Bax and Bcl-2 in the penile cavernous tissue, and the expressions of CBS and CSE were also detected immunohistochemically. The ratio of cavernous smooth muscle to collagen was detected using Masson's Trichrome staining. The apoptosis level of CCSMC was detected by TUNEL + α-SMA immunofluorescence double staining.

RESULTS

After 4 weeks of treatment, the rats in BCNI+NaHS group showed a significantly higher ICP/MAP ratio than those in BCNI group (P < 0.05). The results of Masson's Trichrome staining showed that the ratio of cavernous smooth muscle/collagen was significantly higher in BCNI + NaHS group than in BCNI group (P < 0.05). Western blotting showed a significantly higher expression of α-SMA protein but a lower expression of collagen-I protein in BCNI + NaHS group than in BCNI group (P < 0.05). TUNEL+α-SMA immunofluorescence double staining revealed a significantly lower number of apoptotic CCSMCs in BCNI+NaHS group than in BCNI group (P < 0.05). Compared with those in BCNI group, the rats in BCNI+NaHS group had significantly decreased expressions of caspase-3 and Bax proteins (P < 0.05) with significantly enhanced Bcl-2 protein expression and an increased Bcl-2/Bax ratio (P < 0.05). The expressions of CBS and CSE were significantly lower in BCNI group than in the other two groups (P < 0.05).

CONCLUSIONS

Exogenous H2S enhance the expression of the classic apoptotic protein Bcl-2 and reduces apoptosis of CCSMC to improve the erectile function in rats with BCNI.

Construction of Biofunctionalized Anisotropic Hydrogel Micropatterns and Their Effect on Schwann Cell Behavior in Peripheral Nerve Regeneration

Hydrogels have promising application in tissue regeneration due to their excellent physicochemical and biocompatible properties, whereas anisotropic micropatterns are been proven to directionally induce cell alignment and accelerate cell migration. However, an effect of biofunctionalized anisotropic hydrogel micropatterns on nerve regeneration has rarely been reported. In this study, the anisotropic polyacrylamide (PAM) hydrogel micropatterns with aligned ridge/groove structures were first prepared via in situ free radical polymerization and micromolding, and then biofunctionalized using YIGSR peptide for better promoting cell growth. The morphology, swelling ratio, wettability, mechanical properties, and stability of the prepared hydrogel were characterized. The successful immobilization of YIGSR peptide on the PAM hydrogel was monitored using FTIR, immunofluorescence staining, and ELISA. The effects on adhesion, directional growth, and biological function of Schwann cells were evaluated. The results displayed that the anisotropic PAM hydrogel micropatterns with inner porous structure possessed good stability, swelling, and mechanical properties. The YIGSR peptide could be well immobilized on hydrogel micropatterns with a percentage of 62.6%. The biofunctionalized anisotropic hydrogel micropatterns could effectively regulate the orientation growth of Schwann cells, and obviously up-regulate BDNF (40%) and β-actin (50%) expression compared with single hydrogel micropatterns, without negatively affecting the normal secretion of neurotropic factors by Schwann cells. To the best of our knowledge, this is the first time to study the construction and effect of biofunctionalized anisotropic hydrogel micropatterns on nerve regeneration, which may provide an experimental and theoretical basis for the design and development of artificial implants for nerve regeneration application.