Effects of supplementation with heat shock cognate 17 KDA protein (HSC70) on in vitro bovine embryo viability

Abstract

Endogenous heat shock cognate 71 kDa protein (HSC70) has a vital role in early embryonic development. This study assessed the effects of exogenous HSC70 on bovine embryo development and expression of genes associated with apoptosis. Expression analyses of HSPA1A, HSPA8, Bcl-2, and Bax genes were performed in bovine embryos in vivo on day 7 of development. Subsequently, expression of HSPA1A and HSPA8 were associated with apoptotic genes (Bcl-2 and Bax) in cultured bovine embryos in vitro that were supplemented with various concentrations (0 or control group, 50, and 100 ng) of HSC70. The results indicated that the control group (0 ng) in vitro embryos had higher expression of HSPA8, Bax, and Bcl-2 genes, compared with the vivo embryos (P < 0.01). In vitro-produced embryos supplemented with 50 ng or 100 ng HSC70 had higher expression of HSPA1A, HSC70, Bcl-2, and Bax genes, compared with the control group (P < 0.01). Embryos supplemented with 100 ng had greater expression of the HSPA8 gene compared with the control group and the group supplemented with 50 ng. However, embryos supplemented with 50 ng had better characteristics (i.e., stage of development and quality) than the control and 100-ng groups. In conclusion, supplementation of in vitro culture medium with HSC70 promoted development to the blastocyst stage and improved blastocyst quality.