A team of Danish reproductive biologists has developed a new technique for building a tissue scaffold that mimics a human ovary yet contains no cells. Though a good deal more tests are needed, a series of initial experiments suggest that the structure is capable of supporting ovarian follicles as they mature into oocytes, aka egg cells.
The breakthrough, summarized in a presentation by lead researcher Dr Susanne Pors at the European Society of Human Reproduction and Embryology in Barcelona, could pave the way for an approach that restores fertility in female cancer survivors without risk of cancer recurrence.
Because our current anti-cancer standbys – chemotherapy and radiotherapy – often damage the stash of follicles present in each woman’s ovaries since birth, those who want to conceive after treatment have two options: have a handful of these cell clusters harvested beforehand then turn to IVF when they reach remission, or have the entire ovary harvested then re-implanted. However, due to the possibility that cancerous cells have infiltrated the ovarian tissue, many doctors are leery about signing off on the latter. And, as many couples have experienced, IVF is expensive, exhausting, and not always successful.
Hoping to provide a better option, Dr Pors and her colleagues started tinkering with ways to bioengineer a type of ovarian tissue that is guaranteed to be free of cancerous cells but still maintains the organ’s functionality. Their resulting process begins by harvesting ovarian tissue (the follicles are also taken and frozen) and treating it with a chemical bath until all that remains is the supportive matrix of proteins and collagen. Next, early stage follicles are thawed and reintroduced into the scaffold in the lab.
In their as-of-yet unpublished study, the team demonstrated that follicles removed from cancer patient women integrated well into the artificial ovaries in vitro; showing signs of maturation and cell signaling. Furthermore, when the artificial ovaries were transplanted into mice, one-quarter of the follicles within survived for at least three weeks.
“This is the first time that isolated human follicles have survived in a decellularised human scaffold,” said Dr Pors. She emphasized that the "artificial ovary" poses no risk to the host because cancer cells cannot enter the protective membrane around follicles.
Of course, this proof-of-concept investigation could not answer whether or not the engineered ovaries can thrive after re-implantation in a human woman’s body, and even if it does, the team has no idea how the tissue and follicles will interact with the complex cascade of circulating hormones that guide development of a mature ovum each menstrual cycle.
Daniel Brison, scientific director of the Department of Reproductive Medicine at the University of Manchester, told CNN that although the group’s work appears promising, there is a significant chance that the approach will fail to reestablish fertility because it removes the other types of cells present in an ovary – cells that are likely there for a reason.
However, he concludes that "it is not possible to tell until the data from this research group have been peer-reviewed by the scientific community and published in a scientific journal."