RESUMEN
OBJECTIVE: In the present study, the applicability of hyaluronic acid-alginate (HAA) hydrogel and ovarian cells (OCs) for the culture of mouse ovarian follicles were investigated and compared with those of alginate (ALG) and fibrin-alginate (FA) hydrogels. MATERIALS AND METHODS: In the first step of this experimental study, mechanically isolated preantral follicles from the ovaries of two-week-old mice were encapsulated in the absence or presence of OCs in ALG, HAA, and FA hydrogels and cultured for 14 days. The morphology, diameter, survival and antrum formation rates of the follicles and the maturation and quality of the oocytes were evaluated during culture. In the second step, preantral follicles were cultured similar to the first step, but for 13 days, and their gene expressions and hormonal secretion were assessed on the last day of culture. RESULTS: In the absence of OCs, higher numbers of ALG- and HAA-encapsulated follicles reached the antral stage compared to FA-encapsulated follicles (P<0.05). However, a higher percentage of HAA-developed oocytes resumed meiosis up to the germinal vesicle breakdown (GVBD)/metaphase II (MII) stages in comparison with ALG-developed oocytes (P<0.05). HAA-encapsulated follicles had significant overexpression of most of the growth and differentiation genes, and secreted higher levels of estradiol (E2) compared to ALG- and FA-encapsulated follicles (P<0.05). The co-culture condition increased the diameter of ALG-encapsulated follicles on day 13 of culture (P<0.05). It also increased the survival and maturation rates of ALG- and FA-encapsulated follicles, respectively (P<0.05). The co-culture condition improved cortical granule distribution in all groups, increased E2 and progesterone (P4) secretions in the ALG and FA groups, and androstenedione (A4) secretion in the FA group (P<0.05). CONCLUSION: The present study results show that HAA hydrogel is a promising hydrogel for follicle culture. OCs utilization could ameliorate the culture conditions regardless of the type of hydrogel.
RESUMEN
BACKGROUND: In the present study, the effects of alginate (ALG) concentration and ovarian cells (OCs) on the development and function of follicles were simultaneously evaluated. MATERIALS AND METHODS: In the first step of this experimental study, preantral follicles were isolated from the ovaries of 2-week-old mice, encapsulated in the absence or presence of OCs in 0.5, 0.75 and 1% ALG hydrogels, and cultured for 14 days. The morphology, diameter, survival and antrum formation rates of the follicles and the maturation of the oocytes were evaluated during culture. In the second step, preantral follicles were cultured in the best chosen ALG concentration, in both the absence and presence of OCs. Following these steps, the amount of DNA fragmentation, the expression levels of connexin 37 and connexin 43 proteins, the secretion levels of estradiol, progesterone and androstenedione by the follicles and the quality of mature (MII) oocytes were assessed. RESULTS: Our data revealed that in the absence of OCs, follicles of 0.5% group showed a higher survival rate than the 0.75 and 1% groups (71.87 vs. 52.52 and 40%, respectively, P<0.05). Nonetheless, the antrum formation rate of the 1% group was higher and its oocyte degeneration rate was lower than that in the other groups. Furthermore, it was observed that co-culture of follicles with OCs relatively increased the follicle diameter, survival, antrum formation, and germinal vesicle (GV) to GV break down (GVBD)/MII transition rates. At last, the comparison of 0.5%-OCs and 0.5%+OCs groups indicated that the co-culture condition resulted in more progesterone production (1.8 ± 0.2 vs. 3.2 ± 0.4 ng/ml, respectively, P<0.05) and also decreased oocytes' cortical granule abnormalities (100 vs. 40% for 0.5%- OCs and 0.5%+OCs groups, respectively). CONCLUSION: The present study revealed that 0.5% ALG hydrogel is relatively suitable for preantral follicle culture, and in the presence of OCs, it mimics the natural ovarian condition better than the higher concentrations of ALG hydrogel.
RESUMEN
Our aim was to evaluate the oocyte maturation rate and follicular genes expression pattern during in-vitro culture of vitrified mouse pre-antral follicles. Middle sized pre-antral follicles were isolated mechanically from the ovaries of pre-pubertal mice and distributed in vitrification and control groups. In the vitrification group, follicles were washed in equilibration and vitrification solutions and then were immersed in liquid nitrogen after loading on cryotop tips. After warming in descending concentrations of sucrose solutions, fresh and vitrified-warmed follicles were cultured for 13 days. Follicles survival rate and follicular genes expression were assessed during in vitro culture. Finally, at the end of the culture period oocytes maturation rate were compared in both groups. In the vitrification group, follicles survival rate was lower significantly comparing to the control group (P < 0.05), whereas oocytes maturation rate were similar. Although at the beginning of the culture period, expression of some genes such as Gdf9, Bmp15, Tgfß1 and BmprII were higher in the vitrification group (P < 0.05), during the rest of the culture period expression pattern of all follicular genes were similar in both groups. In conclusion, survival rate of cryotop vitrified pre-antral follicles reduced during culture period while oocytes maturation and follicular genes expression did not show any noticeable alteration.
