Biopolymer gels as a basis of cryoprotective medium for testicular tissue of rats

Collagen-based materials in male genitourinary diseases and tissue regeneration

Male genitourinary dysfunction causes serious physical or mental distress, such as infertility and psychological harm, which leads to impaired quality of life. Current conventional treatments involving drug therapy, surgical repair, and tissue grafting have a limited effect on recovering the function and fertility of the genitourinary organs. To address these limitations, various biomaterials have been explored, with collagen-based materials increasingly gaining attention for reconstructing the male genitourinary system due to their superior biocompatibility, biodegradability, low antigenicity, biomimetic 3D matrix characteristics, hemostatic efficacy, and tissue regeneration capabilities. This review covers the recent biomedical applications of collagen-based materials including treatment of erectile dysfunction, premature ejaculation, penile girth enlargement, prostate cancer, Peyronie's disease, chronic kidney disease, etc. Although there are relatively few clinical trials, the promising results of the existing studies on animal models reveal a bright future for collagen-based materials in the treatment of male genitourinary diseases.

Graphic Abstract

DNA fragmentation, antioxidant activity and histological structure of cryopreserved testicular tissue depending on sexual maturity and immunological status

The objective of this work was to determine a relationship between a frequency of DNA fragmentation, a level of antioxidant activity and a preservation of histological structure depending on initial status of fragments of seminiferous tubules of testes (FSTT) of rats at the stages of cryopreservation. FSTT of animals of different ages (immature, mature), as well as animals with changed immunological status (adjuvant arthritis) were cryopreserved. Slow uncontrolled freezing was used in a cryomedium of fibrin gel with 0.7 M glycerol. The results showed that viability, TAS, γGGT and G6PD activities had the highest values in the group of intact immature animals both in fresh FSTT and after exposure to cryomedium or cryopreservation, while the indexes of DNA fragmentation and ROS content had the lowest values. It was found that an increase in the DNA fragmentation rate occurred in parallel with a decrease in the values of antioxidant activity and membrane integrity. The spermatogenenic epithelium after cryopreservation differed between the groups in a relative number of cells with pathologically changed nuclei and the frequency of exfoliation of epithelial cells into the tubule cavity namely, there was a tendency to an increase in the damaging effects in the series, "Immature → Sexually mature → Autoimmune arthritis". The obtained data can be taken into account in the development of low-temperature preservation protocols using cryotechnologies, which will ensure the maintenance of the morphological and functional characteristics of FSTT depending on sexual maturity and immunological status.

Efficiency of Combined Use of Fullerene C60 and Bovine Serum Albumin for Rehabilitation of Vitrified Fragments of Rat Immature Seminiferous Tubules

Background. Today, cryopreserved reproductive tissues are used to treat some forms of male infertility. However, after long-term preservation of fragments of seminiferous tubules of testes (FSTT) in a low-temperature bank (-196 °С) their morphological and functional characteristics decrease reversibly. To solve this problem after freezing-thawing, the use of rehabilitation media with special additives is promising. Due to the fact that serum albumin and fullerene C60 have powerful protective and antioxidant properties, their use allows to stabilize the plasma membrane, osmotic pressure, and reduce free radicals that make them promising candidates to use in the development of rehabilitation media for biological objects after cryopreservation. Objective. The efficacy of fullerene C60, bovine serum albumin (BSA), and their combination as components of rehabilitation medium of vitrified FSTT of immature rats was studied. Methods. Vitrified-thawed samples of FSTT were incubated (22 °C) for 30 minutes in Leibovitz's medium with addition of 15 mg/mL C60, 5 g/L BSA or their combination. Control samples were incubated in the medium without C60 or BSA addition. Metabolic activity (MTT test), histomorphological data, total antioxidant status (TAS), reactive oxygen species (ROS) production, activity of g-glutamyltransferase (gGGT), and glucose-6-phosphate dehydrogenase were determined in the samples after rehabilitation in the investigated media. Results. The use of C60 led to the increase of metabolic (by 1.26 times) and TAS (by 1.74 times) activities, to the decrease in the number of ROS+ cells (by 1.35 times) and to the improvement of the spermatogenic epithelium binding to the basement membrane versus control sample. Application of BSA did not significantly affect the studied biochemical indices but decreased the number of tubules with desquamation of spermatogenic epithelium in histological sections. The combined use of BSA and C60 had the best effect among investigated rehabilitation media that led to the increase of metabolic activity (by 1.51 times), TAS activity (by 1.78 times), gGGT activity (by 1.59 times), histostructure restoration and the decrease in the number of ROS+ cells (by 1.45 times) compared to the control samples. Conclusions. The use of C60 and BSA combination increases the metabolic and antioxidant activity of vitrified FSTT and also has a positive effect on their histostructural characteristics compared to control samples. It should be noted that the effect of С60 and BSA addition to rehabilitation medium exceeds the results of using the investigated additives separately (by the metabolic and gGGT activity as well as architectonics of vitrified FSTT). These data relate to reproductive medicine and can be used to develop an effective rehabilitation protocol for vitrified FSTT.

Influence of hydrogel encapsulation during cryopreservation of ovarian tissues and impact of post-thawing in vitro culture systems in a research animal model

Objective

Using domestic cats as a biomedical research model for fertility preservation, the present study aimed to characterize the influences of ovarian tissue encapsulation in biodegradable hydrogel matrix (fibrinogen/thrombin) on resilience to cryopreservation, and static versus non-static culture systems following ovarian tissue encapsulation and cryopreservation on follicle quality.

Methods

In experiment I, ovarian tissues (n=21 animals; 567 ovarian fragments) were assigned to controls or hydrogel encapsulation with 5 or 10 mg/mL fibrinogen (5 or 10 FG). Following cryopreservation (slow freezing or vitrification), follicle viability, morphology, density, and key protein phosphorylation were assessed. In experiment II (based on the findings from experiment I), ovarian tissues (n=10 animals; 270 ovarian fragments) were encapsulated with 10 FG, cryopreserved, and in vitro cultured under static or non-static systems for 7 days followed by similar follicle quality assessments.

Results

In experiment I, the combination of 10 FG encapsulation/slow freezing led to greater post-thawed follicle quality than in the control group, as shown by follicle viability (66.9%±2.2% vs. 61.5%±3.1%), normal follicle morphology (62.2%±2.1% vs. 55.2%±3.5%), and the relative band intensity of vascular endothelial growth factor protein phosphorylation (0.58±0.06 vs. 0.42±0.09). Experiment II demonstrated that hydrogel encapsulation promoted follicle survival and maintenance of follicle development regardless of the culture system when compared to fresh controls.

Conclusion

These results provide a better understanding of the role of hydrogel encapsulation and culture systems in ovarian tissue cryopreservation and follicle quality outcomes using an animal model, paving the way for optimized approaches to human fertility preservation.