Embryotropic role of hemoglobin and ethylenediaminetetraacetic acid in preimplantation development of ICR mouse 1-cell embryos

Abstract

Objective: To evaluate embryotropic action of hemoglobin (Hb) and ethylenediaminetetraacetic acid (EDTA) on preimplantation embryo development. Design: In vitro model study using mouse embryos. Setting: University affiliated hospital, Pochon CHA University. Animals: Four-week-old block strain ICR mice naturally mated after superovulation. Intervention(s): One-cell embryos were cultured in serum-free, modified preimplantation-1 medium, to which 1 μg/ml Hb and/or 0.1 mM EDTA were added. Main Outcome Measure(s): Preimplantation development and blastomere number. Result(s): More ( P<.05) 1-cell embryos developed to the 4-cell (52% vs. 67%–84%), 8-cell (48% vs. 65%–81%), and blastocyst (40% vs. 61%–79%) stages after the addition of hemoglobin (Hb) and/or EDTA than after no addition. Highest proportion of embryos developed to each stage after the combined addition of Hb+EDTA. EDTA specifically stimulated the development before the 8-cell stage, which was as similar as Hb+EDTA. On the contrary, higher ratio of morula to blastocyst transformation was obtained after the addition of Hb or Hb+EDTA than after no addition (0.76 vs. 0.96–0.98). Significant increases in the cell number of blastocysts (46.5–47.2 vs. 53.2 cells), inner cell mass (ICM) cells (16.7–17.5 vs. 21 cells), and the ratio of ICM cells to trophoblasts (0.3–0.37 to 0.39) were found after the combined addition of Hb+EDTA, compared with no addition or with the addition of EDTA or Hb alone. Conclusions: Hb and EDTA have stage-specific effects on supporting preimplantation embryo development; Hb promotes both the development before the 8-cell stage and the morula to blastocyst transformation, whereas EDTA mainly promotes the development to the 8-cell stage. The combined exposure of embryos to Hb and EDTA improves not only preimplantation development but also the growth and quality of blastocysts.