Maternal serum supplementation in culture medium benefits maturation of immature human oocytes.

This study compared the rates of maturation, fertilization, cleavage and pregnancy among oocytes matured in medium containing either human serum albumin (HSA) or maternal serum. Immature oocytes were obtained from 51 consecutive regularly cycling women <38 years of age. Immature oocytes were aspirated transvaginally on cycle day 8-9 after priming with FSH (Gonal-F 150 IU/day for 3 days, initiated on day 3). Oocytes were matured in Dyrkningsmedie til IVM supplemented with recombinant FSH (rFSH) 0.075 IU/ml and HCG 0.5 IU/ml for 28-30 h. In group I (n = 63 oocytes obtained from the first 23 cycles) the culture medium was supplemented with 2% (w/v) HSA. In group II (n = 74 oocytes obtained from the following 28 cycles) the medium was supplemented with 10% (v/v) heat-inactivated maternal serum. Intracytoplasmic sperm injection (ICSI) was performed on all methaphase II oocytes. Significantly increased rates of maturation 47/74 (63%) vs. 26/63 (41%) (P < 0.05), pregnancy 6/28 (21%) vs. 0/23 (0%) (P < 0.05) and implantation 6/20 (30%) vs. 0/15 (0%) (P < 0.05) were obtained from oocytes matured in culture medium with maternal serum supplementation compared with oocytes matured in medium supplemented with HSA. These results indicate that factors other than albumin in maternal serum play an important role in maturation and subsequent developmental capacity of human oocytes.