Influence of well defined protein source on in vitro maturation of human oocyte: human follicular fluid versus human serum albumin

Objective: To compare developmental competency of immature human oocytes matured in vitro in G2 media supplemented by two different protein sources. Design: Retrospective comparative study. Setting: University Hospital IVF program. Patient(s): Sixty-five consecutive women from whom at least one immature oocyte was obtained during 76 cycles of ovarian hyperstimulation and IVF. Intervention(s): G2 media containing human follicular fluid (hFF) (from January to August 2005) or human serum albumin (HSA) (from Sep 2005 to Aug 2006) were used for in vitro maturation of immature oocytes. Main Outcome Measure(s): In vitro maturation rate of immature oocytes and their fertilization rate. Result(s): A total of 231 immature oocytes including 107 germinal vesicle (GV) stage and 124 metaphase I (MI) were cultured in vitro and then fertilized by intracytoplasmic sperm injection. The in vitro maturation rate of GV (40.6% vs. 52.0%) and MI oocytes (84.4% vs. 70.0%) and the fertilization rate in GV (76.9% vs. 48.7%) and MI oocytes (70.4% vs. 73.4%) were not different hFF- and HSA-supplemented G2 media. The cleavage rates of embryos generated from either GV or MI were similar between the two groups, but they were seldom used in embryo transfer. Conclusion(s): Developmental competency of immature oocytes was comparable when matured in vitro with G2 media supplemented by either hFF or HSA. Our results suggest that hFF as a protein supplement for human in vitro maturation can be replaced by highly defined HSA.