OBJECTIVE: To assess the effect of human recombinant leukemia inhibitory factor in different doses on human blastocyst formation. SETTING: A university-based tertiary referral center (The Toronto Hospital). INTERVENTIONS: Nontransferable human embryos (n = 473) at the two- to six-cell stage were obtained from patients undergoing IVF and were split randomly into five groups. Embryos in group A (n = 164) were cultured as the control group in Ham's F-10 (GIBCO-BRL, Grand Island, NY) + 10% human sera. Embryos in groups B, C, D, and E (n = 54, 78, 87, and 80, respectively) were cultured in the same medium supplemented with human recombinant leukemia inhibitory factor in four different concentrations (5, 7.5, 10, and 20 ng/mL, respectively). Morphological assessment of embryo development was recorded daily. MAIN OUTCOME MEASURE: Human blastocyst formation. RESULTS: No significant difference was detected in the rate of blastocyst formation of embryos in the study groups when compared with embryos in group A. CONCLUSIONS: This study shows that 5 to 20 ng/mL of recombinant leukemia inhibitory factor in standard medium does not enhance in vitro human blastocyst formation. It is possible that recombinant leukemia inhibitory factor may play a role at later stages of human embryogenesis and during implantation.
OBJECTIVE: To assess the effect of human recombinant leukemia inhibitory factor in different doses on humanblastocyst formation. SETTING: A university-based tertiary referral center (The Toronto Hospital). INTERVENTIONS: Nontransferable human embryos (n = 473) at the two- to six-cell stage were obtained from patients undergoing IVF and were split randomly into five groups. Embryos in group A (n = 164) were cultured as the control group in Ham's F-10 (GIBCO-BRL, Grand Island, NY) + 10% human sera. Embryos in groups B, C, D, and E (n = 54, 78, 87, and 80, respectively) were cultured in the same medium supplemented with human recombinant leukemia inhibitory factor in four different concentrations (5, 7.5, 10, and 20 ng/mL, respectively). Morphological assessment of embryo development was recorded daily. MAIN OUTCOME MEASURE: Humanblastocyst formation. RESULTS: No significant difference was detected in the rate of blastocyst formation of embryos in the study groups when compared with embryos in group A. CONCLUSIONS: This study shows that 5 to 20 ng/mL of recombinant leukemia inhibitory factor in standard medium does not enhance in vitro humanblastocyst formation. It is possible that recombinant leukemia inhibitory factor may play a role at later stages of human embryogenesis and during implantation.