Can Matrigel substitute for Vero cells in promoting the in-vitro development of mouse embryos?
The influences of Vero cells and the basement membrane substratum for these cells (Matrigel) on the rate of hatched blastocyst formation from mouse zygotes in vitro were compared. Zygotes obtained from C57BL/6 x BALB/c F1 females pretreated with pregnant mare's serum gonadotrophin/human chorionic gonadotrophin mated with BDF1 males were cultured (120 h) in human tubal fluid medium supplemented 0.5% with bovine serum albumin. The rates of early hatching and hatched blastocyst formation at 96 and 120 h of culture were expressed as the percentage of 2-cell embryos visualized after the initial 24 h. The rate of total blastocyst formation did not differ between treatment groups. However, < 10% of embryos cultured for 96 h in medium alone advanced to the hatching stage compared with 35-40% of blastocysts cultured with Vero cells or with Matrigel alone. Similarly, by 120 h of culture, only 20% of embryos cultured in medium alone developed to hatching or hatched blastocysts compared with > 70% for those embryos co-cultured with Vero cells or with Matrigel. In conclusion, Vero cells improved the rate of development of mouse embryos to hatched blastocysts during serum-free culture. Similar improvements were seen in the presence of Matrigel alone; Matrigel is the basement membrane substratum used for the Vero cells. Further studies on the means whereby Matrigel promotes early embryonic development (e.g. appropriate combination of basement membrane-associated growth factors) may lead to a safe, defined medium preparation for the stimulation of in-vitro development of human embryos.