Slow-Freezing Cryopreservation Ensures High Ovarian Tissue Quality Followed by In Vivo and In Vitro Methods and Is Safe for Fertility Preservation

Abstract

Background and objectives: Cancer incidence is growing with younger patients diagnosed with this disease every year. Improved cancer diagnostics and treatment lead to better survival of cancer patients. However, after aggressive chemo- or radiotherapy, cancer survivors suffer from various degrees of subfertility or infertility. Several fertility preservation technologies have been developed for young cancer patients: cryopreservation of germ cells, embryos, or reproductive tissues. The best results have been shown by cryopreservation of sperm and embryos. Yet the success of using cryopreserved oocytes or reproductive tissues (ovarian and testicular) is still insufficient. Therefore, this study was designed to assess the vitality, viability, general quality, and safety of frozen–thawed human ovarian tissue for retransplantation using modern molecular tests. Materials and Methods: The new miRNA array test was used to evaluate miRNA expression in thawed ovarian tissue in combination with standard xenotransplantation and pathological examination of microslides. Results: Our results demonstrated that slow freezing is an efficient way (80%) to cryopreserve ovarian tissue with no structural damage afterwards. We have shown that xenotransplantation into immunodeficient mice, histology, and immunohistochemistry could be potentially replaced by more recent molecular methods. Conclusions: The latter method has shown that altered expression of miRNAs might be used as identifiers of normal/damaged tissue after further analysis. Newer, safer, and more specific approaches need to be developed in order to eliminate the risk of disease reoccurrence.

The hypo-osmotic swelling test: Is it a sperm vitality or a viability assay?

“…Differentiation between, and assessments of, cell viability vs. vitality are also of critical interest in other fields of biology, such as in the assessment of yeast cells (29,30), stem cells (31), and ovarian tissue after cryopreservation (32). It is important that the terms ''vitality'' and ''viability'' be used and applied properly for the sake of scientific clarity, consistency, and accuracy.…”

Fertility preservation in pediatric healthcare: a review

“…Roughly 50% of the cortex from one ovary is surgically removed, dissected, and cryopreserved for future use ( 82 , 83 ). The ovarian tissue is cryopreserved by either slow freezing ( 84 – 86 ) or vitrification ( 87 ). When a patient intends to restore ovarian function and/or fertility, the cryopreserved tissue can be thawed and replaced ( Figure 1B ).…”

Female Oncofertility: Current Understandings, Therapeutic Approaches, Controversies, and Future Perspectives

“…For OTC, recent advances allow examination of tissue vitality; structural, functional, and DNA integrity; malignant cell contamination; and detection of molecular tumor markers [ 231 ]. One study reported that the implementation of a new miRNA array test in the slow-freezing protocol could yield a rate of human ovarian tissue with no structural damage as high as 80% [ 232 ].…”