Reconstruction of the ovary microenvironment utilizing macroporous scaffold with affinity-bound growth factors.

Implementing ovarian tissue engineering for the maturation of primordial follicles, the most abundant follicle population in the ovary, holds great potential for women fertility preservation. Here, we evaluated whether macroporous alginate scaffolds with affinity-bound bone morphogenetic protein-4 (BMP-4) could mimic the ovary microenvironment and support the culture and growth of primordial follicles seeded with supporting ovarian cells. Porcine primordial follicles developed in the alginate scaffolds up to the pre-antral stage within 21 days. Affinity-bound BMP-4 significantly contributed to follicular maturation, as evident by the 5-fold increase in the number of developing follicles and enhanced estradiol secretion in these cultures compared to when BMP-4 was added to cultures with no affinity binding. After 21 days in culture, an increase in GDF-9/AMH gene expression, which is correlated with follicular development, was statistically significant when BMP-4 was affinity bound, compared to all other scaffold groups. When developed in-vivo, after xeno-transplantation of the follicle devices supplemented with additional angiogenic factors, the follicles reached antral size and secreted hormones at levels leading to restoration of ovarian function in ovariectomized severe combined immunodeficiency (SCID) mice. Altogether, our results provide first affirmation for the applicability of macroporous alginate scaffolds as a suitable platform for promoting follicle maturation in-vitro and in-vivo, and lay the foundations for the advantageous use of affinity binding presentation of growth factors to cultured follicles.