Beneficial Effect of Polysaccharide Gel Made of Xanthan Gum and Locust Bean Gum on Bovine Oocytes.

The present study examined the effect of polysaccharides gels made of xanthan gum and locust bean gum (gel culture system) on oocyte maturation and explored the molecules causing the beneficial effect of the gel culture system. Oocytes and cumulus cells complexes were collected from slaughterhouse-derived ovaries and cultured on a plastic plate or gel. The gel culture system improved the rate of development to the blastocyst stage. The oocytes that matured on the gel contained high lipid contents and F-actin formation, and the resultant 8-cell stage embryos had low DNA methylation levels compared to their plate counterparts. RNA sequencing of the oocytes and embryos revealed the differentially expressed genes between the gel and plate culture systems, and upstream regulator analysis revealed estradiol and TGFB1 as top activated upstream molecules. The medium of the gel culture system contained higher concentrations of estradiol and TGFB1 than that of the plate cultures system. Supplementation of the maturation medium with either estradiol or TGFB1 resulted in high lipid content in oocytes. In addition, TGFB1 improved the developmental ability of the oocytes and increased F-actin content while reducing DNA methylation levels in the 8-cell stage embryos. In conclusion, the gel culture system is useful for embryo production, potentially through the upregulation of TGFB1.