The use of recombinant growth factors to promote human embryo development in serum-free medium

Research into human implantation requires embryo culture systems that yield high numbers of good quality blastocysts. One approach is to use coculture but the presence of feeder cells and serum may confound analysis of paracr ine or autocrine factors involving blastocyst implantation. An alternative approach is to produce a defined serum-free culture medium supplemented wit h growth factors. We have shown that the addition of Leukaemia Inhibitory F actor increased blastocyst formation from 18.4-43.6% but none of these embr yos developed beyond day 7 or hatched, suggesting that additional factors a re required. Development to the blastocyst stage was significantly increase d to 71.0% in the presence of 100 nM heparin-binding epidermal growth facto r (HB-EGF) and 81.0% of these embryos went on to hatch, No difference in bl astocyst quality between the control and HB-EGF-treated embryos was found. These experiments clearly demonstrate the potential of this system to gener ate blastocysts in vitro. Further investigation of the normality of these b lastocysts must be carried out before they are used clinically, since it ha s been demonstrated in other species that apparent improvements in culture conditions may be detrimental to pregnancy outcome.