Fibrin-alginate hydrogel supports steroidogenesis, in vitro maturation of oocytes and parthenotes production from caprine preantral follicles cultured in group

This study aimed to establish a culture system that improves the in vitro development of caprine preantral follicles. In a first experiment, follicles were encapsulated as a single unit per bead and cultured singly or in groups or with five follicles in the same alginate (ALG) bead for 18 days. In a subsequent experiment, the "five follicles per bead" design was chosen to culture in ALG, fibrin-alginate (FA) or hyaluronate (HA) for 18 days. In a third experiment, we chose the five follicles per bead in FA to culture for 30 days. The culture set-up of five follicles per ALG bead increased antrum formation and follicle diameter compared to the other culture designs (p<.05). Moreover, under this condition, 44.44% of the oocytes from in vitro cultured preantral follicles reached meiotic resumption. A significant increase of follicle diameter occurred in attachment system and FA (p<.05), but the ALG condition reached the highest among all groups on day 18 (p<.05). Follicles encapsulated in matrix produced more estradiol and progesterone than attachment system (p<.05). The expression of MMP-9 mRNA was higher in FA than in other groups (p<.05) and similar to antral follicles from in vivo control (p>.05). Only FA group resulted in oocytes matured. After 30 days, oocytes from preantral follicles in vitro grown in FA developed to eight-cell parthenotes. In conclusion, a culture system using FA supported the development of caprine preantral follicles cultured in group and included in the same bead of hydrogel, improving the oocyte maturation and producing parthenotes.