Expression of apoptosis-related proteins in human fragmented embryos

Abstract

Objective: It has recently been hypothesized that fragmentation in embryos is a consequence of apoptosis and that highly fragmented embryos have a poor prognosis for survival. The main objects of this study are to determine whether apoptosis occurs in fragmented embryos and to characterize the expression of apoptosis-related molecules in human embryos. Design: A total of 33 embryos (16 fragmented and 17 non-fragmented embryos) was obtained from the IVF-ET program. We detected apoptosis in embryos, and compared the expression of apoptosis-related proteins in embryos between fragmented embryos and non-fragmented embryos. Materials/Methods: Human fragmented and non-fragmented embryos were used to detect apoptosis by annexin staining. The expression of bcl-2, bax, fas, and fas ligand (fasL) was determined by immunofluorescent staining and western blotting. Results: Phosphotidylserine translocation, the marker for apoptosis, was detected frequently in fragmented embryos. The frequencies of expression of apoptosis-related molecules in fragmented embryos and non-fragmented embryos were: 3/4 (75%), 5/5 (100%) for bcl-2; 3/3 (100%), 3/4 (75%) for bax; 5/5 (100%), 2/4 (50%) for fas; 0/4 (0%), 0/4 (0%) for fasL, respectively. The western blotting results showed that bcl-2, bax, fas were expressed in both fragmented and non-fragment embryos, while fasL was not expressed. Conclusions: Our data showed that fragmentation in human embryos is associated with apoptosis. In this study, fas was expressed in both fragmented and non-fragmented embryos, whereas fasL was not expressed. Although bcl-2 and bax were expressed in both fragmented and non-fragmented embryos, the degree and localization of expression were different according to fragmentation. These results suggest that the ratio of Bcl-2/bax may be related to regulation of the apoptosis in human embryos. Supported by: Not supported.