Impact of Ovarian Aging in Reproduction: From Telomeres and Mice Models to Ovarian Rejuvenation

The trend in our society to delay procreation increases the difficulty to conceive spontaneously. Thus, there is a growing need to use assisted reproduction technologies (ART) to form a family. With advanced maternal age, ovaries not only produce a lower number of oocytes after ovarian stimulation but also a lower quality—mainly aneuploidies—requiring further complex analysis to avoid complications during implantation and pregnancy. Although there are different options to have a child at advanced maternal age (like donor eggs), this is not the preferred choice for most patients. Unless women had cryopreserved their eggs at a younger age, reproductive medicine should try to optimize their opportunities to become pregnant with their own oocytes, when chances of success are reasonable. Aging has many causes, but telomere attrition is ultimately one of the main pathways involved in this process. Several reports link telomere biology and reproduction, but the molecular reasons for the rapid loss of ovarian function at middle age are still elusive. This review will focus on the knowledge acquired during the last years about ovarian aging and disease, both in mouse models of reproductive senescence and in humans with ovarian failure, and the implication of telomeres in this process. In addition, the review will discuss recent results on ovarian rejuvenation, achieved with stem cell therapies that are currently under study, or ovarian reactivation by tissue fragmentation and the attempts to generate oocytes in vitro.