Safe and high-quality fertility preservation is of growing significance for women in clinical trials. Current primary methods for cryopreserving human oocytes are slow freezing and vitrification, but existing techniques poses risks of biochemical toxicity and are restricted in large-scale clinical practice.

To solve the issue, research teams led by Professor Zhao Gang from University of Science and Technology of China (USTC), together with Professor Cao Yunxia from the First Affiliated Hospital of Anhui Medical University (AHMU) and Professor Liu Huanzhong from the Chaohu Hospital Affiliated to Anhui Medical University (AHMU), developed a multi-scale ice inhibition platform that enables full-cycle cryogenic protection for mouse oocyte. The result was published in Advanced Functional Materials.

Overview of the cryopreservation procedure of oocytes and the schematic diagram of the multi-scale ice inhibition platform  (Image by USTC)

The multi-scale ice inhibition platform is based on a nanomaterial, polyvinyl alcohol/Fe3O4/graphene oxide nanoparticles (PFG NPs), offering comprehensive cryogenic protection throughout the entire cycle of oocyte cryopreservation. Subsequently, by using lower concentrations of cryoprotectants (without DMSO and with extremely low toxicity), researchers achieved high-efficiency and batch cryopreservation of mouse MII oocyte.

The PFG NPs synthesized by researchers have the potential to reduce the degree of supercooling and eliminate the formation of sharp ice crystal morphologies. Additionally, PFG NPs remarkably reduce the IR injury, temperature gradient and devitrification that can do harm to cell condition during rewarming process. The oocyte preserved by this platform displayed fewer gene variations compared to those using traditional methods, while maintaining their ability for successful offspring birth, demonstrating significant potential in establishing cryobanks dedicated to fertility preservation.

(Written by ZHANG Yuhuan, edited by JIANG Zhimo, USTC News Center)