EVANSTON, Ill. --- Women at risk for infertility, such as those needing cancer treatment, can freeze mature, fertilized eggs, but the process can take up to six weeks and for some this delay of treatment is not an option.
Immature follicles (the female egg and surrounding somatic cells) can be preserved at any time but are difficult to mature when removed from their normal environment.
A team of scientists from Northwestern University has developed a three-dimensional culture system that encapsulates follicles and allows immature eggs to grow and mature in vitro. (A follicle is a small spherical group of specialized support cells surrounding each egg.) This novel technology has already led to the live birth of healthy mice from in vitro grown follicles.
The results are published online this month by the journal Tissue Engineering.
The study shows that follicles grown individually in a three-dimensional biomaterial called alginate maintain normal connections between follicle and egg, resulting in the development of eggs, which can be fertilized and ultimately lead to healthy embryos and the birth of live mice. Previously developed methods of growing follicles or eggs outside of the body do not provide the three-dimensional support to maintain the follicle structure in which the egg must grow.
“While the research is in its early stages, this work has implications for the preservation of fertility for women and girls with cancer,” said Teresa K. Woodruff, Professor of Neurobiology and Physiology who led the study together with Lonnie D. Shea, Associate Professor of Chemical and Biological Engineering. “This system establishes a core technology for human egg banks for preservation of fertility.”
The technology mimics the ovary and its environment. Follicles (each follicle has one egg) from mice were grown in vitro until fully matured by providing the follicles and eggs with the necessary hormones for development while maintaining their normal architecture. The eggs were then used for in vitro fertilization. The fertilized eggs were implanted into a foster mother that was of a different strain than the donor egg and sperm, resulting in babies with a different coat color, proving that the births were the result of the cultured embyros. Both male and female offspring were fertile.
In addition to Woodruff and Shea, other authors on the paper are Min Xu and Pamela K. Kreeger, both from Northwestern.
The research was supported by the National Institute of Child Health and Human Development through the Northwestern University Specialized Centers Program in Reproductive Research (SCCPRR, U54).