Effect of Human Leukemia Inhibitory Factor on Bovine Embryos Obtained by in Vitro Fertilization

PREREZ BEASCOCHEA; SUELDO C,; SALAMONE D

USA

Congreso; American Society for Reproductive Medicine; 2005

American Society for Reproductive Medicine

Objective LIF is a cytokine with an important role in early embryo development (Stewart C, 1994), and it was shown that human LIF (hLIF) is critical in maintaining the totipotentiality of embryonic stem cells (Williams R, 1988). Also, it appears to improve the development of parthenogenic bovine embryos (Fukui Y,1994) as well as previously frozen bovine embryos (Han Y,1995). To evaluate the effect of hLIF on the early development of bovine embryos obtained by IVF and in their capability to reach the stage of blastocyst Design Experimental animal study Materials and methods Small 4-6 mm follicles were aspirated from the bovine ovaries and the obtained oocytes cultured in groups of 20-25 in TCM-199 for 24 hs. Cryopreserved bovine semen was used for in vitro fertilization. Embryos were then cultured in CR2 at 37 C in 5% CO2 in air. The cultures were supplemented with hLIF(100 ng/ml) at 72 hs from aspiration (102 embryos) or not (66 embryos, served as controls). A new set of embryos obtained in the same manner were supplemented with hLIF(100 ng/ml) at 144 hs (70 embryos) or not (58 embryos, served as controls). All the embryos with hLIF had exposure again to hLIF at 196 hs (100 ng/ml). After 8 days in culture the rate of blastocyst formation was determined in both groups, experimental and controls.Statistical analysis was done by ÷2, a p<0.05 was considered significant. Results The culture supplementation with hLIF at 100 ng/ml 72 hs post-insemination showed a blastocyst rate of 7.84% (n=102 embryos), which was not statistically different from the 7.57 % obtained with control embryos free of hLIF (n=66 embryos). The same was true when hLIF was added at 144 hs post-insemination (also 100 ng/ml), the blastocyst rate was 5.7 % (n=70 embryos) which was not different from the 5.1 % (n=58 embryos) seen with control embryos free of hLIF. Conclusion Under the experimental conditions used in this research project, the addition of hLIF to bovine embryos in culture did not increase the percentage of blastocysts obtained. Although LIF has been postulated to be a positive factor in the implantation process, clearly does not increment the embryo growth to blastocysts.