On the 8th of September Spyridon Panagiotis Deligiannis will defend their thesis “Multi-omics insights into ovarian health preservation”.
Supervisors:
Professor of Reproductive Medicine Andres Salumets, University of Tartu
Docent Timo Tuuri, University of Helsinki (Finland)
Tenure Track Associate Professor Agne Velthut-Meikas, Tallinn University of Technology
Opponent:
Associate Professor Paul Wieringa, Maastricht University (Netherlands)
Summary
Advances in cancer treatment mean that more patients are surviving than ever before. However, treatments such as radiotherapy can severely damage the ovaries, threatening future fertility. While most research has focused on how radiation destroys eggs (follicles), much less is known about how it affects the ovarian support cells that are essential for healthy ovarian function. Protecting fertility is therefore a growing priority, and ovarian tissue cryopreservation (OTC), the freezing and storage of ovarian tissue, is an increasingly used option. Yet, there is no standard method for doing this, and its long-term effectiveness still needs improvement.
This doctoral research explored how common fertility-preservation strategies affect ovarian tissue at the cellular and molecular level. First, it examined how radiation exposure alters ovarian support cells. The results showed that radiation causes lasting damage to these cells, disrupting their ability to divide, repair DNA, and organise tissue, effects that occur even without direct damage to eggs. This suggests that ovarian failure after cancer treatment may involve more than follicle loss alone.
Second, the thesis investigated vitrification, a rapid freezing method used in OTC. While vitrified ovarian tissue appeared normal immediately after thawing, longer-term culture revealed reduced follicle survival and changes in key developmental pathways, including those involved in hormonal regulation. These findings point to specific molecular targets that could help refine cryopreservation protocols.
Finally, the study tested whether the ovary contains its own unique microbiome, a community of bacteria that might influence ovarian health or cryopreservation success. After rigorous testing and contamination controls, no evidence of a resident ovarian microbiome was found.
Together, this work provides new insight into how cancer treatments and fertility-preservation techniques affect ovarian tissue, helping to guide future improvements in fertility care for patients undergoing gonadotoxic therapies.
