Fertility preservation through gonadal cryopreservation

Assessment of apoptosis and oxidative stress in cryopreserved ovary after grafting in fibrin-alginate scaffold with endothelial cells and melatonin in wistar rats

OBJECTIVE

Infertility is a significant public health concern affecting 10-15% of couples. Young women undergoing gonadotoxic treatment are at higher risk of ovarian dysfunction and infertility. To mitigate this risk, ovarian tissue freezing and transplantation have been developed as a novel strategy. However, challenges such as follicular loss and dysfunction during the freezing process, and ovarian damage during transplantation, persist. This study aimed to investigate the potential of using appropriate antifreeze, antioxidant, wound healing, and biological hydrogels to reduce these injuries. Specifically, the effect of fibrin scaffold with endothelial cells and melatonin on apoptotic gene expression and antioxidants in cryopreserved ovaries after transplantation was examined.

METHODS

A total of 36 adult female wistar rats) 6-8-week-old and weighing from 200 to 220 g) were divided equally into six groups (n = 6): 1) control group (C), 2) transplanted ovarian tissue after vitrification and thawing process (Group 1), 3) transplanted vitrified/thawed ovarian tissue while encapsulated in Fib/Alg hydrogel (Group 2), 4) transplanted vitrified/thawed ovarian tissue while encapsulated in Fib/Alg hydrogel in addition with melatonin (Group 3), 5) transplanted vitrified/thawed ovarian tissue while encapsulated in Fib/Alg hydrogel in addition with endothelial cells (Group 4) and 6) transplanted vitrified/thawed ovarian tissue while encapsulated in Fib/Alg hydrogel in addition with melatonin endothelial cells (Group 5). The ovaries were auto-transplanted in the rats' lumbar region. After 14 days, the ovaries were removed. Antioxidant levels (SOD, GPx, MDA, and TAC) were evaluated using ELISA, and apoptotic gene expressions (Bax/Bcl2 and caspase 3) were analyzed by real-time RT-PCR to determine apoptosis.

RESULTS

In the transplanted frozen ovary group, Bax/Bcl2 and caspase 3 gene expression increased significantly (P<0.05), while antioxidant levels (SOD, GPx, MDA, and TAC) decreased. The encapsulated frozen ovary group showed decreased gene expression and increased antioxidant levels. The ovary group encapsulated with fibrin scaffold, endothelial cells, and melatonin had the most significant decrease in gene expression and increase in antioxidant levels (P<0.05).

CONCLUSION

Coordinated action of Fibrin-based scaffold with endothelial cells and melatonin could decrease apoptosis gene expression and increase antioxidant levels in cryopreserved ovaries after transplantation, providing valuable insights into preserving fertility in young women undergoing gonadotoxic treatment.

Erythropoietin effects on cryopreserved/transplanted cat ovarian tissue: A comparison of two incubation methods

Many feline species are currently threatened with extinction. Therefore, germplasm bank establishment has become imperative. However, cryoinjury and ischemia-reperfusion injury pose significant obstacles to both cryopreservation and xenotransplantation. In this regard, erythropoietin (Epo) represents a potential alternative strategy due to its properties. This study aimed to assess the incubation of domestic cat ovarian tissue in Epo, both before and after cryopreservation, and investigate its effectiveness in promoting revascularization following xenotransplantation. Sixteen ovaries from 8 healthy cats were sliced following elective bilateral ovariohysterectomy (OHE). Subsequently, 8 fragments measuring 3 mm³ each were obtained from the cortical region of each ovary. The fragments were allocated into 3 treatment groups: Cryo group, fragments were cryopreserved, thawed and immediately transplanted; Cryo + Epo group, fragments were first cryopreserved in nitrogen, thawed, incubated in Epo (100 IU) for 2h and transplanted; and the Epo + Cryo group, in which fragments were first incubated in Epo (100 IU) for 2h, cryopreserved, thawed and immediately transplanted. The fragments were then xenotransplanted into the dorsal subcutaneous region of ovariectomized female nude mice and retrieved at 7, 14, 21, and 28 days post-transplantation. The results indicated that Epo effectively enhanced follicular survival, preservation of viability, and tissue revascularization. The Epo + Cryo group displayed better revascularization rates on D14 and D21 post-transplantation and an increase in primordial and growing follicles on D28, the Cryo + Epo group exhibited significantly more follicles on D14 and D21, with fewer degenerated follicles.

Advances in Genetic Reprogramming: Prospects from Developmental Biology to Regenerative Medicine

The foundations of cell reprogramming were laid by Yamanaka and co-workers, who showed that somatic cells can be reprogrammed into pluripotent cells (induced pluripotency). Since this discovery, the field of regenerative medicine has seen advancements. For example, because they can differentiate into multiple cell types, pluripotent stem cells are considered vital components in regenerative medicine aimed at the functional restoration of damaged tissue. Despite years of research, both replacement and restoration of failed organs/ tissues have remained elusive scientific feats. However, with the inception of cell engineering and nuclear reprogramming, useful solutions have been identified to counter the need for compatible and sustainable organs. By combining the science underlying genetic engineering and nuclear reprogramming with regenerative medicine, scientists have engineered cells to make gene and stem cell therapies applicable and effective. These approaches have enabled the targeting of various pathways to reprogramme cells, i.e., make them behave in beneficial ways in a patient-specific manner. Technological advancements have clearly supported the concept and realization of regenerative medicine. Genetic engineering is used for tissue engineering and nuclear reprogramming and has led to advances in regenerative medicine. Targeted therapies and replacement of traumatized , damaged, or aged organs can be realized through genetic engineering. Furthermore, the success of these therapies has been validated through thousands of clinical trials. Scientists are currently evaluating induced tissue-specific stem cells (iTSCs), which may lead to tumour-free applications of pluripotency induction. In this review, we present state-of-the-art genetic engineering that has been used in regenerative medicine. We also focus on ways that genetic engineering and nuclear reprogramming have transformed regenerative medicine and have become unique therapeutic niches.

Trehalose delivered by cold-responsive nanoparticles improves tolerance of cumulus-oocyte complexes to microwave drying

PURPOSE

Trehalose is a non-permeable protectant that is the key to preserve live cells in a dry state for potential storage at ambient temperatures. After intracellular trehalose delivery via cold-responsive nanoparticles (CRNPs), the objective was to characterize the tolerance of cat cumulus-oocyte complexes (COCs) to different levels of microwave-assisted dehydration.

METHODS

Trehalose was first encapsulated in CRNPs. After exposure to trehalose-laden CRNPs, different water amounts were removed from cat COCs by microwave drying. After each dehydration level, meiotic and developmental competences were evaluated via in vitro maturation, fertilization, and embryo culture. In addition, expressions of critical genes were assessed by quantitative RT-PCR.

RESULTS

CRNPs effectively transported trehalose into COCs within 4 h of co-incubation at 38.5 °C followed by a cold-triggered release at 4 °C for 15 min. Intracellular presence of trehalose enabled the maintenance of developmental competence (formation of blastocysts) as well as normal gene expression levels of HSP70 and DNMT1 at dehydration levels reaching up to 63% of water loss.

CONCLUSION

Intracellular trehalose delivery through CRNPs improves dehydration tolerance of COCs, which opens new options for oocyte storage and fertility preservation at ambient temperatures.

Comparison between slow freezing and vitrification of ovarian tissue cryopreservation in assigned female at birth transgender people receiving testosterone therapy: data on histological and viability parameters

PURPOSE

The use of fertility preservation (FP) techniques has significantly increased in recent years in the assigned female at birth (AFAB) transgender population. Oocyte cryopreservation is the established method for FP, but ovarian tissue cryopreservation may be considered an alternative option, especially during gender-affirming surgery (GAS). The slow freezing (SF) cryopreservation technique is the standard method for human ovarian tissue, but recently, several studies have shown good results with the vitrification (VT) technique. The objective of this study was to compare the effectiveness of VT and SF techniques in ovarian tissue from AFAB transgender people.

METHODS

This was a prospective study including 18 AFAB transgender people after GAS. Ovarian tissue pieces from each ovary were cryopreserved by SF and VT and compared with fresh tissue. Study by light microscopy (LM) assessed follicular morphology and density. The percentage of surviving and degenerated follicles was studied with the tissue viability test. Oocytes, granulosa cells and stroma were analysed separately by transmission electron microscopy.

RESULTS

The VT technique preserves follicle and stromal tissue as well as the SF method, but with some differences. Evaluation by LM showed better follicle preservation with VT, but the ultrastructural study showed the presence of minor damage with both techniques compared to fresh tissue.

CONCLUSION

Both cryopreservation techniques are accurate for maintaining the follicular population and stromal tissue. Further studies are needed to determine the impact of VT on ovarian tissue and the subsequent follicular activation mechanisms in AFAB ovarian tissue.

Influence of Microwave-Assisted Drying on Structural Integrity and Viability of Testicular Tissues from Adult and Prepubertal Domestic Cats

Anhydrous preservation is a promising approach for storage of living biomaterials at nonfreezing temperatures. Using the domestic cat model, the objectives of this study were to characterize changes in histology, DNA integrity, and viability of testicular tissues from adult versus prepubertal individuals during microwave-assisted drying. Testes from each age group were cut into small pieces before reversible membrane permeabilization, exposure to trehalose, and microwave-assisted drying during different time periods. In Experiment 1, water content was monitored for up to 40 minutes of drying. Tissues from adult or prepubertal cats experienced similar decreases of water content during the first 10 minutes. Desiccation progressed slowly between 10 and 20 minutes and then remained stable. In Experiment 2, structural properties were explored at 5, 10, and 20 minutes of desiccation. Percentages of normal seminiferous tubules were lower after 20 minutes drying in adult (43%) than in prepubertal tissues (61%). At the same time point, the proportion of cell degeneration was higher in adult (53%) than prepubertal tissues (28%). Percentages of intact DNA in tissues remained above 85% regardless of the microwave time in both age groups. Lastly, adult and prepubertal tissues only lost 33% of viability in both age groups. Collective results demonstrated for the first time that normal morphology, incidence of degeneration, DNA integrity, and viability of testicular tissues remained at acceptable levels during microwave-assisted drying for 20 minutes. Overall, prepubertal testicular tissues appeared to be more resilient to microwave-assisted desiccations than adult tissues. Importantly, water loss in the presence of trehalose after 20 minutes of desiccation already is compatible with long-term storage of testicular tissues at temperatures above -20°C, which is one step closer to future storage at supra-zero temperatures.

Preservation of female fertility in humans and animal species

A detailed understanding of the cryobiology of gametes and complex tissues has led to the development of methods that facilitate the successful low temperature banking of isolated mature human oocytes, or immature oocytes in situ within fragments of human ovarian cortex. Although many outstanding research challenges remain to be addressed, the successful development of new treatments to preserve female fertility for a range of clinical indications has largely been underpinned by the conduct of extensive, fundamental research on oocytes and ovarian tissues from a number of laboratory and commercially important farm species. Indeed, the most recent evidence from large animals suggests that it is also possible to cryopreserve intact whole ovaries along with their supporting vasculature for later auto-transplantation and restoration of natural fertility. This review will explore how the methods developed to preserve human oocytes and ovarian tissues can now be used strategically to support the development of conservation strategies aimed at safeguarding the genetic diversity of commercially important domestic animals and also of preserving the female germplasm for wild animals and endangered species.

Developmental competence of in vitro matured ovine oocytes vitrified in solutions with different concentrations of trehalose

This study aimed to determine the optimum concentration of trehalose in solutions used for vitrification of in vitro matured (IVM) ovine oocytes. IVM oocytes were randomly divided into four experimental (vitrified) and one control (fresh) groups. Experimental groups were treated with different concentrations (0.0, 0.25, 0.5 and 1.0 M) of trehalose. After warming, some viable oocytes were exposed to 0.25% pronase to test zona pellucida hardening, whereas the others were fertilized and cultured in vitro for 8 days to evaluate their developmental competence. Blastocysts quality was assessed by differential staining and TUNEL test. Survival and developmental rates of oocytes vitrified in the presence of 0.5 M trehalose were significantly higher than those of the other vitrified groups. Furthermore, there was a significant difference between fresh and vitrified groups in total blastocyst rate. Analysis of blastocysts quality also revealed a significant difference between the group treated with 0.5 M trehalose and other groups in terms of apoptotic index. Furthermore,zona pellucida digestion time period was longer in trehalose-free (0.0 M) group compared to other groups. In conclusion, we found that IVM ovine oocytes vitrified in solutions containing 0.5 M trehalose are fertilization-competent and are able to produce good-quality blastocysts with an apoptotic index comparable to that of the fresh oocytes. Therefore, 0.5 M may be considered the optimum concentration of trehalose to be used in solutions prepared for vitrification of oocytes.

Ovarian fragment sizes affect viability and morphology of preantral follicles during storage at 4°C

The method of transportation and the conditions imposed on the ovarian tissue are pivotal aspects for the success of ovarian tissue cryopreservation (OTC). The aim of this study was to evaluate the effect of the size of the ovarian tissue (e.g. whole ovary, biopsy size and transplant size) during different times of storage (0, 6, 12 and 24 h) on the structural integrity of equine ovarian tissue transported at 4°C. Eighteen pairs of ovaries from young mares (<10 years old) were harvested in a slaughterhouse and processed to simulate the fragment sizes (biopsy and transplant size groups) or kept intact (whole ovary group) and stored at 4°C for up to 24 h in α-MEM-enriched solution. The effect of the size of the ovarian tissue was observed on the morphology of preantral follicles, stromal cell density, DNA fragmentation and mitochondrial membrane potential. The results showed that (i) biopsy size fragments had more morphologically normal preantral follicles after 24 h of storage at 4°C; (ii) mitochondrial membrane potential was the lowest during each storage time when the whole ovary was used; (iii) DNA fragmentation rate in the ovarian cells of all sizes of fragments increased as storage was prolonged and (iv) transplant size fragments had increased stromal cell density during storage at cool temperature. In conclusion, the biopsy size fragment was the best to preserve follicle morphology for long storage (24 h); however, transportation/storage should be prior determined according to the distance (time of transportation) between patient and reproduction centers/clinics.