Rieger, D.; Schimmel, T.; Cohen, J.; Cecchi, M.
Introduction: Embryos are routinely cultured under oil in standard cell-culture dishes, in microdrops of medium that can flatten or run together. The embryos can be difficult to locate and examine at the edge of the microdrop. In the GPS dish, the medium is constrained in microwells. The bottoms of the wells are concave and parafocal to facilitate location and examination of the embryos. The objectives of this study were to the compare the time required for preparation and embryo evaluation, and to compare the development of mouse embryos, between microdrop culture and culture in the GPS wells.
Materials & Methods: On Day 0, ten standard 60 mm dishes (Nunc 150288, VWR Scientific) and ten GPS dishes (IVFonline, developed by authors TS, JC & MC) were loaded with 13 ml of oil. In each standard dish, eleven 50 µl microdrops of KSOM + 10 mg/ml BSA were under-laid on the surface of the dish. In each GPS dish, 50 µl of medium was under-laid into each of 11 wells. All dishes were held overnight at 37.3°C under 5% CO2 in air. On Day 1, 100 mouse zygotes were randomly assigned to be cultured in microdrops in the standard dishes, or in microwells of the GPS dishes. In each standard dish, 5 embryos were washed through 3 microdrops and placed in individual microdrops for culture. In GPS dishes, 5 embryos were washed through 3 wells and cultured in individual wells. Embryo development was evaluated on Days 2, 3, 4 and 5 and compared between the dish types by Chi-square analysis. The times to set-up, and to evaluate each dish on each day, were recorded and compared between the dish types by Kruskal-Wallis tests.
Results: A significantly greater proportion of embryos cultured in GPS dishes developed to the morula stage and compacted on Day 3, compared with embryos cultured in microdrops in standard dishes (Table 1). There were no differences in development on Days 2, 4 or 5. The mean times required to set-up the dishes on Day 1, and to evaluate the embryos on Day 2, 3, 4 and 5, were all significantly less for GPS dishes than for standard dishes (Table 2).
Conclusions: Development to blastocyst by Day 5 was not different between embryos cultured in wells of the GPS dish and those cultured in microdrops in standard dishes, indicating that the GPS dishes support embryo development as well as do the standard dishes. The times required to set up the dishes and to evaluate the embryos were all significantly less for the GPS dishes than for the standard dishes. It is not clear why development on Day 3 was better for embryos cultured in the GPS dishes than for those cultured in the standard dishes, but may be related to the reduced time outside the incubator. The results suggest that the use of GPS dishes for human embryo culture could reduce time and labor costs in ART laboratories, and perhaps improve embryo development.