For years, scientists have sought to create a human artificial ovary, restoring fertility in patients without other options. The first cellular map of a human ovary, recently developed at the University of Michigan, Ann Arbor, represents a big leap forward in that quest.
“You cannot build something if you don’t have the blueprint,” said biomedical engineer Ariella Shikanov, PhD, associate professor at University of Michigan, who helped create what she and colleagues call an atlas of the ovary. “By creating a map or an atlas, we can now follow what nature created and engineer the building blocks of an ovary — and build a nature-like structure.”
So far, the concept of an artificial ovary has been successful only in mice, with the development of a 3D-printed prosthetic ovary that enabled sterilized mice to have pups. Researchers hope that artificial human ovary technology could someday help women left infertile after cancer treatment, as well as patients who don›t respond to fertility treatments and those with premature ovarian failure.
But Dr. Shikanov believes this research will go even further, providing a valuable resource to scientists studying diseases and other conditions related to the ovary.
“Whenever people think about the ovary, if they think about it at all, they usually think about fertility,” said Dr. Shikanov. The ovary is so much more.
Besides producing and carrying a woman’s unfertilized eggs during her lifetime, the ovary is also responsible for endocrine function — the production of estrogen and progesterone, which in addition to supporting reproductive health, help maintain a woman’s cardiovascular, bone, and mental health.
“We don’t really understand everything that is happening in the ovary yet,” Dr. Shikanov said. “But we know it is an important organ.”
Mapping the Ovary
Because people don’t typically donate their ovaries, there are not many available for research, especially from younger reproductive age women, said Dr. Shikanov. So, the scientists set out to build a resource. They described their work in Science Advances.
To create their atlas, the researchers studied two premenopausal donor ovaries, profiling 18,000 genes in 257 regions. From three additional donor ovaries, they also generated single-cell RNA sequencing data for 21,198 cells.
“We identified four major cell types and four immune cell subtypes in the ovary,” said Dr. Shikanov. Taking samples from different areas of the ovary revealed distinct gene activities for oocytes, theca cells, and granulosa cells — expanding scientists’ understanding of the molecular programs driving ovarian follicle development.
What’s unique about their work is the focus on both single cell and spatial analysis, said study coauthor Jun Z. Li, PhD, associate chair of the University of Michigan’s department of computational medicine and bioinformatics. Specifically, they used a relatively new method called spatial transcriptomics, which allows them to see which genes are being activated and where.
“We are constructing the spatial arrangement of the cells in the ovary,” said Dr. Li. “This spatial analysis is like saying, ‘Let me look at where you are and who your neighbor is.’ ”
Their findings are built on other genetic and cellular research in the field, Dr. Li noted. Biomedical engineers in other areas of medicine are applying similar technologies to other organs including the heart, the breast, and bone — part of a larger project called the Human Cell Atlas.