Beneficial effects of coculture with cumulus cells on blastocyst formation in a prospective trial with supernumerary human embryos

Abstract

Purpose: We reported previously on the use of coculture with cumulus cells in insemination medium for the development of human embryos in vitro. Here we describe a prospective trial to determine if this procedure has a significant beneficial effect. Methods: On the day after insemination, zygotes were randomized for culture in either a fresh drop of medium without (− cum) or were left in their insemination drop with (+ cum) cumulus cells. Embryos with the best morphological quality were replaced on the third day of development at the eight-cell stage. The remaining embryos were cultured for a further 3 days and cryopreserved if they reached the fully expanded blastocyst (FEB) stage. Three different culture media were used over the period of this study. Results: In 11 patients, supernumerary embryos were available only for continued culture in + cum and three patients had embryos cultured in only − cum. Thirty-nine other patients had embryos assigned to both + cum and − cum treatments. In the + cum group, 98 blastocysts developed from 216 embryos cultured for 6 days (45%), and this was significantly greater (PConclusions: The culture of human embryos with their cumulus cells in insemination drops of medium produces a significantly greater proportion of FEBs than when the zygotes are transferred to fresh culture drops devoid of cumulus cells. This is the first report of a significantly higher blastocyst rate with coculture in which a real comparison has been made between two culture treatments which differ only in the presence or absence of homologous cumulus cells in insemination drops.