Three-Dimensional Ovary Model to Improve and Study Murine Follicle Growth.

To increase chances for women with impaired gonadal function to conceive biological offspring in vitro platforms for cultivating small follicles are developed. These rely mainly on the manual supplementation of required hormones and growth factors. We hypothesize that within a 3D ovary model, direct interactions between stroma cells and follicles would improve follicle viability and growth, thereby resulting in a larger pool of mature follicles. In this study, a transglutaminase crosslinked poly(ethylene glycol) (TG-PEG) is adapted in its stiffness and functionalized with the cell adhesion peptide RGD to allow growth of follicles and to render it bioactive. During seven days of culture, the follicles grow, retain important morphological characteristics, and oocytes acquire meiotic competence. Following this, a co-culture system that utilizes either paracrine signaling between follicles and supporting cells or a co-culture that relies on direct contact is employed, confirming improved follicle growth when cultured with support cells. Confocal imaging reveals formed cell-cell interactions between support cells and follicles in detail. This newly developed ovary model consisting of a highly tunable TG-PEG hydrogel, follicles, and support cells facilitates functional follicle growth in vitro and allows to study follicle-stroma cell interactions to help improve fertility preservation techniques.