3D-printed scaffolds with controlled-releasing compounds for ectopic activation of dormant ovarian follicles

Throughout a woman’s reproductive life, hundreds of functioning follicles are activated for development, while thousands of dormant follicles remain in the ovaries. Dormant follicle activation in vitro is an effective clinical strategy for women with fertility needs who suffer from ovarian dysfunction. However, activating dormant follicles in vivo is still a challenge due to difficulties such as delivering stimulators to local sites. Here, we developed a compound-preloaded microporous scaffold by combining three-dimensional (3D) printing techniques with pharmacological activators to support and stimulate the activation and development of primordial follicles. The gelatin/alginate composite scaffolds exhibited exceptional mechanical properties and biological compatibility, effectively supporting the survival of ovarian granulosa cells for more than 7 days, which is essential for oocyte development. Furthermore, the ovarian tissue-scaffold complex successfully survived after transplantation under the mouse kidney capsule, demonstrating its excellent biocompatibility. After pre-mixing widely used clinical activators into the bio-ink, the scaffold had the ability to gradually release the mixture of compounds, effectively activating primordial follicles. By transplanting the ovary-scaffold complex containing activators into the mouse abdominal subcutaneous pocket, dormant follicles could be activated subcutaneously and developed into growing follicles. The number of growing follicles is approximately three times higher compared to the group without activators. In conclusion, by integrating biomaterials, activators, and 3D printing technology, we have developed 3D-printed biological scaffolds that can ectopically support primordial follicle activation and development in vivo. This novel approach could provide a promising strategy for treating ovarian insufficiency and endocrine disorders in the clinic, without the need for in situ ovarian tissue grafting.