Human ampullary co-cultures for blastocyst transfer in assisted reproduction

Although the assisted reproductive techniques (ART) have contributed significantly over the last decade in alleviating subfertility in the childless couple, the implantation and take-home baby rates have been stubbornly low. A major cause for such low success rates has been the reduced viability of replaced embryos perhaps induced by the suboptimal in vitro conditions used in ART laboratories. One approach to improving embryo viability is to provide the growing embryo with a simulated in vivo environment by replicating the conditions existing in the human fallopian tube in vitro. This requires either the maintenance of an intact fallopian tube in vitro or establishment and maintenance of tubal epithelial cell-lines which could be used as feeder layers for early embryonic growth. The concomitant growth of cells with embryos in vitro has been referred to as co-culture. This paper discusses the in vitro behaviour of human tubal epithelial cells, the fertilisation and growth of embryos in ampullary co-culture, the specificity of co-cultures, the mechanism of action of co-cultures and the methods of screening the human ampullary co-culture system for microbes. The pregnancy and implantation results on 50 patients enrolled for a co-culture clinical trial are presented and the future use of this system discussed.