Functional follicles created for the first time from stem cells in the mouse:

A major breakthrough in reproductive biology: artificial follicles from stem cells

Molecular biologists from Kyushu University (Japan), led by Professor Katsuhiko Hayashi, have made a significant scientific advancement in the field of in vitro gametogenesis (IVG). This innovative technology allows for the reprogramming of somatic cells, including skin cells, into induced pluripotent stem cells. From these, it is then possible to obtain fully functional reproductive cells. This technique opens new perspectives in the treatment of infertility, particularly for individuals who have lost their fertility due to illness or age-related changes.

Professor Hayashi's team began their work in 2016 when they successfully obtained mouse eggs from stem cells for the first time. However, at that stage, ovarian tissues were needed to complete the process, as they created a specific microenvironment necessary for the development of oocytes. Over the next five years, the scientists worked hard to eliminate this dependency, aiming to create a fully autonomous in vitro system that does not require biological tissues.

After extensive research, the Japanese scientists succeeded in culturing three-dimensional structures similar to natural ovarian follicles from stem cells. These structures function as biological "incubators," creating the conditions in which oocytes can mature and transform into viable reproductive cells. This revolutionary approach was made possible through the activation and suppression of four key genes: WNT, BMP4, SHH, and FGF. Each of these plays an important role in cellular differentiation and tissue development. The precise tuning of their expression allowed for the modeling of the natural processes of folliculogenesis.

The experimental results were impressive. The laboratory-obtained eggs were successfully fertilized and transplanted into female mice. A pregnancy was established, and healthy offspring were born. Their physiological development, genetic activity, and behavior were indistinguishable from those of naturally conceived mice. This confirmed the viability of the obtained cells and the effectiveness of the developed system.

This discovery has generated particular interest in the context of clinical reproductive medicine. The possibility of creating eggs from somatic cells could potentially save women suffering from premature ovarian failure, patients with cancer after chemotherapy, and couples undergoing long-term infertility treatments. However, scientists emphasize that there is still a long way to go before IVG can be used in humans: further research on safety, stability of the genome, and exclusion of mutation risks is needed. Additionally, the use of this technology raises serious bioethical and legal questions.

Despite the challenges ahead, Professor Hayashi's discovery is already recognized as one of the most important milestones in modern reproductive biology. It expands scientific understanding of the processes of egg maturation and could radically change the approach to infertility treatment in the future. The molecular creation of gametes, which recently seemed to belong to the realm of science fiction, is becoming a reality.

The publication of this data in the prestigious scientific journal Science highlights the importance of this research and attests to its high scientific level. It is a signal to the global scientific and medical community: IVG technologies are gradually moving out of laboratories and approaching practical application in the medicine of the future.

Kyushu University. (2021). Building the ovarian environment from stem cells. https://www.kyushu-u.ac.jp/en/researches/view/217/