Assessment of Estrogen Receptors and Apoptotic Factors in Cryopreserved Human Ovarian Cortex

Short-Term PTEN Inhibition Improves In Vitro Activation of Primordial Follicles, Preserves Follicular Viability, and Restores AMH Levels in Cryopreserved Ovarian Tissue From Cancer Patients

Introduction

In vitro activation and growth of primordial dormant follicles to produce fertilizable oocytes would provide a useful instrument for fertility preservation. The employment of Phosphatase and TENsin homolog (PTEN) inhibitors, in combination with Protein kinase B (Akt) stimulating molecules, has been previously employed to increase follicular activation through the stimulation of the PTEN-Akt pathway.

Methods

We aim to establish improved in vitro activation also for cancer patients whose ovarian tissue has already been cryopreserved. Fresh and previously cryopreserved human ovarian cortex were exposed to short-term, low-concentration and ovary-specific treatment with only a PTEN inhibitor.

Results

Our in vitro activation protocol enhances the activation mechanisms of primordial follicles in both fresh and cryopreserved samples, and enlarges growing populations without inducing apoptosis in either follicles or the surrounding stroma. Treatment augments estradiol secretion and restores the expression levels of the previously diminished Anti-Müllerian hormone by means of cryopreservation procedures. Genomic modulation of the relative expression of PTEN pathway genes was found in treated samples.

Conclusion

The in vitro activation protocol offers new alternatives for patients with cryopreserved tissue as it increases the pool of viable activated follicles available for in vitro growth procedures. The combination of ovarian tissue cryopreservation and in vitro activation of primordial follicles, the main ovarian reserve component, will be a major advancement in fertility preservation.

Assessment of vitrification outcome by xenotransplantation of ovarian cortex pieces in γ-irradiated mice: morphological and molecular analyses of apoptosis

PURPOSE

The aim of this study was the investigation of caspase-3/7 activity and apoptosis related gene expression after vitrification and xenotransplantation of human ovarian fragments.

METHODS

Ovarian specimens were obtained from normal female-to-male transsexual women during laparoscopic surgery and cut into small pieces and were considered as vitrified and non-vitrified groups. The morphological study, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, caspase-3/7 activity and apoptosis related gene expression analysis were done in both non-vitrified and vitrified groups in two steps (before transplantation of ovarian tissues and 30 days after transplantation).

RESULT(S)

In spite of high rate of normal follicles in both non-transplanted tissues these rates were significantly decreased in vitrified and non-vitrified grafted tissues, moreover grafted-vitrified tissue showed significantly less normal follicles than grafted-non-vitrified group (P < 0.05). The expression of some pro and anti-apoptotic genes in vitrified-warmed tissues were not changed compared to non-vitrified ones but the expression of Fas and caspase8 was increased and the expression of BRIC5 was decreased in this group (P < 0.05). In transplanted vitrified group the Bcl2, FasL and BRIC5 gene expression was high and caspase8 was low (P < 0.05). The expression of all genes in both grafted groups was more than non-grafted tissues except for caspase8 (P < 0.05). The TUNEL positive signals and caspase-3/7 activity were increased in both grafted groups compared to non-grafted groups and this enzyme activity in grafted-vitrified group was more than grafted-non-vitrified group (P < 0.05).

CONCLUSION(S)

This study provides the first evidence on the significant effect of vitrification on follicular apoptosis of grafted human ovarian tissue at mRNA level. The signs of follicular survival or degeneration detected by morphological assessment and caspase-3/7 activity were closely correlated to the changes in expression of apoptosis-related genes.

Human ovarian tissue vitrification/warming has minor effect on the expression of apoptosis-related genes

BACKGROUND

In this study, we evaluated the incidence of apoptosis at the ultrastructural levels and expression of some apoptosis-related genes in vitrified human ovarian tissue just after warming.

METHODS

Human ovarian tissue biopsies from 23 women after caesarean section were transported to the laboratory within 2 hours, and then they were cut into small pieces. Some pieces were vitrified and warmed and the other samples were considered as control. Apoptosis was assessed by a transmission electron microscope and also by molecular analysis of pro-apoptotic (Fas, FasL, Bax, p53, caspase8, and caspase3) and antiapoptotic (Bcl-2 and BIRC5) genem RNA levels using real-time RT-PCR before and after vitrification.

RESULTS

No sign of apoptosis was shown ultrastructurally in vitrified samples. The level of FasL, Bcl-2, Bax, p53, and caspase3 mRNA and Bax:Bcl-2 ratio were similar in non-vitrified and vitrified groups; however, the expression of Fas and caspase8 genes was higher and BIRC5 was lower in vitrified samples compared to non-vitrified group (P<0.05).

CONCLUSION

The fine structure of human vitrified ovarian tissue was well preserved; moreover, vitrification was shown to affect the expression of some apoptosis-related genes. However, additional study is needed to confirm this observation.

In vitro development of human primordial follicles to preantral stage after vitrification

PURPOSE

The aim was to culture primordial follicles in vitro to reach preantral stage in vitrified human ovarian tissue.

METHODS

Ovarian tissue samples were obtained from six women. Tissue strips were vitrified by infiltration with a cryoprotectant followed by mounting on a stainless steel carrier. After culturing for 7 days the morphology and developmental stages of follicles enclosed in fresh and vitrified groups were analyzed.

RESULTS

High proportion of viable follicles in vitrified ovarian strips was obtained. After culturing for 7 days the percentage of secondary and preantral follicles increased significantly (P < 0.05) whereas primordial and transitory follicles showed a significant decrease (P < 0.05) compared to their respective counterparts at day 0 of culture.

CONCLUSIONS

Vitrification of ovarian strips with an improved carrier device and culturing of follicles in ovarian strips after warming yielded developed follicles with high viability and morphological integrity that may be suitable for use in fertility preservation among cancer patients.

Apoptosis of human ovarian tissue is not increased by either vitrification or rapid cooling

This study evaluated the incidence of morphological changes, as assessed by light microscopy, and apoptosis in vitrified and rapidly cooled human ovarian tissue. Apoptosis was assessed 30 min and 24h after warming using transmission electron microscopy, terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling (TUNEL) assay and DNA fragmentation, as determined by gel electrophoresis. The results showed no significant changes in morphology, chromatin condensation, DNA fragmentation or TUNEL-positive cells in follicles attributable to cryopreservation or exposure to the cryoprotectant solutions alone. In conclusion, the cryopreservation protocols did not affect the incidence of apoptosis and either protocol could be an alternative to slow cooling of ovarian tissue. This study evaluated the incidence of morphological changes, as assessed by light microscopy, and apoptosis in human ovarian tissue cryopreserved using two different methods, i.e. vitrification and rapid cooling. Apoptosis was assessed in tissue 30 min and 24h after warming using transmission electron microscopy and terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling (TUNEL) assay and DNA fragmentation as determined by gel electrophoresis. The results showed no significant changes in morphology, chromatin condensation, DNA fragmentation or TUNEL-positive cells in follicles attributable to cryopreservation or exposure to the cryopreservation solutions alone. In conclusion, the cryopreservation protocols did not affect the incidence of apoptosis in human ovarian tissue and either protocol could be an alternative to slow cooling for the preservation of ovarian tissue.

Identification of genes for normalization of quantitative real-time PCR data in ovarian tissues

Increased attention has been paid to the determination of the potential biomarker and therapeutic target for ovarian cancer in recent years. However, the normalization of quantitative real-time PCR is important to obtain accurate gene expression data. We investigated the stability of 20 reference genes in ovarian tissues under different conditions to determine the most adequate for this application. The study characterized the expression of 20 possible reference genes among 52 ovarian tissue samples involving the normal, non-malignant, and primary ovarian carcinomas. One-way analysis of variance (ANOVA) method was used to compare the candidate gene changes brought about by the disease progression. The stability and suitability of the genes with no statistic difference were further validated employing geNorm and NormFinder softwares. Results showed that the expression levels of the 20 reference genes varied, while the RPL4, RPLP0, HSPCB, TPT1, RPL13A, 18S rRNA, PPIA, TBP, and GUSB kept statistic stability despite different ovarian tissue conditions. RPL4, RPLP0, and HSPCB were demonstrated as the most stable reference genes and the combination of the RPLP0 and RPL4 should be recommended as a much more reliable normalization strategy.