Potential of Mouse and Human Embryonic Fibroblasts to Support Mouse Embryo Development Following Exposure to Laboratory Temperature

Purpose: Present study was designed to evaluate the potential of co-culture systems to overcome deleterious effect of exposure of mouse 2-cell embryos to low temperature. Materials and Methods: 2-cell embryos were flushed from oviduct of super ovulated NMRI mice into HTF medium with 15% BSA. After washing 3 times with HBSS and with 15% BSA, embryos were exposed to laboratory temperature (LT) (22-24 ° C) for 1, 3 and 5 hours. Embryos in each group were simultaneously transferred into drops of HTF, MEM-a as control as well as Mouse Embryonic Fibroblast (MEF) and Human Embryonic Fibroblast (HEF) as treatment. All the embryos were incubated in humidified 37° C incubator with 5% CO2 in air for 120 hours.Experiments were replicated 6 times and development of embryos was recorded every 24 hours for 5 days. Data were analyzed with c2 test and any statistic difference with p<0.05 was considered significant. Results: Development of the embryos following 5 hour exposure to LT decreased significantly (p<0.05) after 4 and 5 days cultivation in HTF and MEM-a when compared to control. Co-culture of the embryos with either MEF or HEF increased the rate of blastocyst formation in all the groups that had been exposed to LT. No significant difference was noted between the embryos in co-cultured control group and experimental groups. A sharp increase in development of the embryos, which were exposed to LT for 5 hours and co-cultured with the feeder cells after 4 and 5 days, was observed when compared with MEM- a group (p-<0.05). Conclusions: We conclude that mouse 2-cell embryos can withstand deleterious effect of LT for less than 3 hours. However, keeping embryos for 5 hours at LT decreases the rate of development. Either cell employed in present study enhanced development of embryos especially when the embryos were exposed to LT.