An oocyte-derived biomaterial provides a “sperm safe” to preserve mammalian spermatozoa
Cancer treatments such as radiation, chemotherapy, and surgery, while life preserving, can threaten fertility. Fertility preservation in males with conditions of extremely low numbers of germ cells is difficult (e.g. cryptozoopsermia or testicular/epididymal biopsy samples). Fortunately, with intracytoplasmic sperm injection (ICSI), fertility can be restored with technically only a single sperm. Despite the success of ICSI, a significant challenge is the lack of robust and reliable methods to store and recover small numbers of sperm. Through the generous support of the Pediatric Oncofertility Research Foundation and the Daniel J. Manella Research Grant, Dr. Francesca Duncan, PhD in collaboration with Dr. Hoi Chang Lee, PhD (Northwestern University) engineered an oocyte-derived biomaterial – the zona pellucida (ZP) – to function as a “sperm safe” for storing sperm, and we validated the efficiency and efficacy of this method for cryopreservation, storage, and recovery. The ZP is a coating that surrounds the mammalian oocyte. Dr. Duncan and Dr. Lee used a decellularization process to remove cellular material from the ZP, leaving behind a purified scaffold. Decellularization is an established method in biomedical engineering for generation of artificial organs and tissue regeneration purposes. The application of decellularization of the zona pellucida has not been described and represents a major advance in the ability to apply this technology clinically to store small numbers of sperm. This discovery could have significant impact on Assisted Reproduction Technologies in the fertility preservation setting and beyond.
Image of three mouse sperm heads stored in a purified ZP