In Vitro Models to Study Trophoblast Function and Dysfunction— A Workshop Report

Thiede first used trypsin to dissociate and culture term trophoblast. Most current methods use variations of a trypsin-DNAse procedure devised by Hall (Hall et al., 1977; Bloxam, Bax and Bax, 1997a b). All methods appear to yield cells that display a cytotrophoblast phenotype (see caviat below), do not proliferate, have some invasive ability (but significantly less than first trimester cytotrophoblast), and spontaneously differentiate in varying degrees into syncytium with strong expression of a wide range of specific syncytial biochemical products even if morphological fusion does not occur. The cells can effectively be used to study cytokine actions on the placenta, metabolism, transport, and syncytial formation, eg as induced by EGF. All evidence to date indicates that syncytia formed in vitro behave the same as in vivo syncytium and may thus be considered a useful model of this cell type (Morrish et al., 1997). Term cytotrophoblasts have been used in one and two-sided culture (Bloxam et al., 1997b) and can be made to form a confluent barrier for viral penetration studies (Hemmings et al., 2001). Because of the abundance of tissue available, molecular