Culture of bovine embryos in buffalo rat liver cell-conditioned media or with leukemia inhibitory factor.

Experiments were designed to study development of bovine embryos in TCM-199 medium conditioned by preculture with buffalo rat liver (BRL) cells. Conditioned media were harvested after BRL cells were cultured until confluency (CON), or for an additional 2 d with the same cells but new medium (CON-N) or the same medium (CON-S). Glucose in TCM-199 was depleted by BRL cells to different concentrations depending on coculture procedures: CON = 3.94 mM, CON-N = 1.67 mM, and CON-S = 1.11 mM glucose. In Exp. 1, development of bovine zygotes in CON-S resulted in fewer blastocysts than development in CON (10 vs 28%, P < .05); CON-N was not different from CON (26% blastocysts). Experiment 2 examined effects of moving embryos to a fresh drop of different or identical conditioned medium after culture for 3 d. Initial culture in CON-N and final culture in CON resulted in a greater (P < .01) number of blastocysts compared with the control of CON followed by CON (32 vs 19% blastocysts). This was not entirely due to changing from low to high glucose because adding glucose to CON-N after 3 d yielded only 18% blastocysts. To test the hypothesis that beneficial effects of BRL cell-conditioned media may be due to secretion of leukemia inhibiting factor (LIF), LIF was added to B2, a more appropriate medium than Medium-199 for culturing bovine embryos without conditioning or coculture with BRL cells. In the absence of serum, the percentage of blastocysts per cleaved embryo (17 to 28%) was not improved with LIF; however, the mean number of cells per blastocyst was higher (P < .05) in treatments with LIF (65 to 74 cells) than without LIF (47 cells). In B2 medium + 10% fetal calf serum, LIF was of no benefit; development to blastocysts was good with or without LIF (43% of cleaved).