Aloe vera increases mRNA expression of antioxidant enzymes in cryopreserved bovine ovarian tissue and promotes follicular growth and survival after in vitro culture

Abstract

The aims of the present study were to evaluate the effects of Aloe vera extract on expression of mRNA for antioxidant enzymes in bovine ovarian tissue after vitrification, as well as on follicular morphology, viability, activation and extracellular matrix in cultured ovarian tissues that had been previously vitrified. Fragments from bovine ovarian cortical tissue were cryopreserved in a vitrification solution alone or supplemented with two concentrations of Aloe vera (10 or 50%). After thawing, the cryopreserved tissues were analyzed by histological techniques, as well as the levels of mRNA for SOD, CAT, PRDX6 and GPX1 were investigated. Furthermore, cryopreserved fragments were then culture in vitro in α-MEM for 6 days. Histological evaluation of cultured tissues was performed to determine the percentages of normal and developing follicles. The results showed that, after vitrification, the presence of Aloe vera in both concentrations was able to maintain percentages of collagen fibers similar to fresh tissues (P < 0.05). Aloe vera in both concentrations significantly increased mRNA levels for PRDX6 and GPX1 in cryopreserved tissues, while 10% Aloe vera increased mRNA levels for SOD (P < 0.05). In parallel, after in vitro culture, fragments vitrified in the presence of 10% Aloe vera had significantly higher levels of morphologically healthy follicles when compared to tissue that were vitrified without Aloe vera. In fragments vitrified with Aloe vera, the rate of developing follicles was significantly higher than in tissues vitrified without Aloe vera. Tissues vitrified with 10% Aloe vera and cultured in vitro maintained percentages of collagen fibers similar to fresh tissues. In conclusion, 10% Aloe vera increases the expression of mRNA for PRDX6, GPX1 and SOD in vitrified ovarian tissues, maintains follicular survival and promotes activation and development of follicles after in vitro culture of vitrified bovine ovarian tissue.