COCULTURED HUMAN EMBRYOS MAY BE SUBJECTED TO WIDELY DIFFERENT MICROENVIRONMENTS - PATTERN OF GROWTH-FACTOR CYTOKINE RELEASE BY VERO CELLS DURING THE COCULTURE INTERVAL

This study was designed to identify and quantify concentrations of gro wth factors/cytokines released by Vero cells during the co-culture int erval, The factors screened for in this preliminary investigation, nam ely platelet-derived growth factor (PDGF), transforming growth factor beta (TGF beta), interleukin-6 (IL-6), leukaemia inhibitory factor (LI F) and epidermal growth factor (EGF) have each been identified to impa ct on early embryo development or are secreted by embryos themselves, suggesting an autocrine regulatory role, Vero cell culture supernatant s were collected at 2, 3, 4, 5 and 6 days after seeding. Samples were assessed by enzyme-linked immunoassay for growth factor/cytokine secre tion at each designated time interval, Conditioned medium from all day s contained IL-6, PDGF and LIF. The concentration of IL-6 increased fr om 293 pg/well on day 2 to almost 1600 pg/well on day 6, PDGF also acc umulated rapidly in co-culture wells, rising from 19-40 pg/well early in the culture period to around 500 pg/well by day 6, In the second ha lf of this study, medium supernatants from patients enrolled in our co -culture programme were analysed. Retrospective evaluation of medium s upernatants collected at the time of transfer from co-cultures from 11 randomly selected patients showed considerable patient-to-patient var iation in concentrations of secreted growth factors and cytokines, The se findings indicate that during the co-culture interval embryos are e xposed to a dynamic environment, with increasing concentrations of gro wth factors and cytokines, The positive effects of co-culture on embry o quality and in-vitro blastulation need to be balanced against the va riation that this technique can potentially introduce into the embryo culture system.