Researchers in the US have bioengineered an artificial ovary that makes sex hormones in the same proportions as a healthy one. They report that in the lab setting at least, the bioengineered ovary shows sustained released of sex hormones estrogen and progesterone, and suggest it may provide a more natural option for women than hormone replacement therapy.

Ovaries produce eggs and also secrete sex hormones that are important for women’s bone and heart health.

Women who are post-menopausal or whose ovaries are damaged or have been removed, don’t produce sex hormones, which can lead to undesirable effects ranging from hot flashes and vaginal dryness to infertility. There is also an increased risk of osteoporosis and heart disease.

But while drug-based hormone replacement therapy (HRT) can help, it is often not recommended for long-term use due to the increased risk of heart disease and breast cancer.

Reporting in the March issue of Biomaterials, Emmanuel Opara at Wake Forest University, North Carolina, and colleagues, describe how using tissue from rats, they made a bioartificial ovary by placing two hormone-producing ovary cells in an algal capsule to simulate the natural follicular environment, and then stimulated it using pituitary gland hormones.

The capsule has a membrane that is thin enough to allow oxygen and nutrients to enter.