Source of protein supplementation during in vitro culture does not affect the quality of resulting blastocysts in the domestic cat.

The objective of this study was to assess and compare the quality of cat blastocysts produced in vitro using commercial blastocyst growth media supplemented with different sources of proteins (serum protein substitute from in vitro maturation through embryo development vs 4 mg/ml of bovine serum albumin for maturation and 5% foetal calf serum for fertilization and embryo development). Impact was specifically examined on the proportion of blastocyst formation, total number of blastomeres, proportion of inner cell mass and expression of pluripotency marker proteins NANOG and OCT-4. Blastocyst formation per total cleaved embryos was similar (p > 0.05) regardless of the protein supplementation. There were no differences (p > 0.05) between culture conditions regarding average number of blastomeres and proportion of inner cell mass in each embryo. Presence of OCT-4 protein was detected in nuclei of both trophectoderm and inner cell mass region, with a stronger signal in the latter regardless of the culture medium. NANOG protein also was present in the inner cell mass regardless of the in vitro culture condition. We therefore demonstrated that serum protein substitute was as good as semi-defined protein sources for the production of good-quality blastocysts and embryonic stem cells. In addition, a single defined medium could be successfully used for cat oocyte maturation, in vitro fertilization and embryo development.