O-198: Leukemia inhibitory factor (LIF) induce cumulus expansion in immature human and mouse oocytes and improves mouse fertilization and delivery rates when it is present during mouse in vitro oocyte maturation (IVM)

Abstract

Studies have demonstrated that LIF concentrations are higher in preovulatory follicles than in developing follicles and a positive correlation exists between follicular fluid LIF concentration and embryo quality. Therefore we decided to examine the role of LIF during human and mouse IVM on cumulus expansion and oocyte competence. Mouse and human oocyte cumulus expansion was evaluated during IVM. Mouse oocyte competence was determined by IVF, IVC and embryo transfer (ET). Adult B6CBAF1/J females were primed with 5 IU of PMSG. Oocytes were collected 48 hs later. Immature human oocytes (4 donors, 25 oocytes) were collected after COH with rhFSH at the time of anticipated hCG administration. IVM medium was Alfa-MEM (Gibco 32571-036) supplemented with 10 % HSS (human oocytes) or FCS (mouse oocytes) and 1.5 IU rhCG. Oocyte treatments during IVM were ± rFSH and ± LIF (mouse 18 h and human 48 h) and cumulus expansion was evaluated. Mouse IVM oocytes, but not human oocytes continued to IVF and IVC for 4 days. Experimental groups: IVM oocytes ± 0.2 IU rFSH; IVM oocytes ± rFSH + LIF (0.1, 1, 1000 ng/ml); and in vivo matured (ovulated) oocytes. Mouse embryo development in vitro was recorded to Day 4, and blastocysts from all groups (395 blastocysts), were transferred to the uterine horn of 2.5-Day pseudopregnant females. Delivery rates were recorded. Logarithmic transformed data were analyzed by ANOVA and Tukey’s test. Results are expressed as Mean ± SE. LIF alone in the IVM medium induced cumulus expansion in human and mouse oocytes. There were no significantly differences between the standard IVM medium supplemented with rFSH vs. supplemented with LIF (P>0.05). But, when 1000 ng/ml LIF was added in combination with rFSH, a significant increase in cleavage rate, embryo development rate (Blastocyst/Total oocytes) and birth rate was observed when compared to oocytes matured with FSH alone (P<0.05). The birth rate of the IVM + rFSH + 1000 ng/ml LIF group was comparable to the in vivo matured control (endogenously ovulated oocytes) (P>0.05). In summary, LIF induced cumulus expansion similarly in human and mouse cumulus-oocyte complexes, and IVM with rFSH + LIF during mouse IVM significantly improved oocyte competence as measured by cleavage rate, blastocyst development and birth rate Our results demonstrate that LIF induces cumulus expansion in human and mouse oocytes and has a profound effect on mouse IVM oocyte competence improving live birth rates. These results strongly suggest that addition of LIF and FSH to IVM media may improves the efficiency of human IVM in ART.