Villous trophoblasts cultured on semi-permeable membranes form an effective barrier to the passage of high and low molecular weight particles

An effective in vitro model of the placental villous syncytium cultured on semi-permeable substrata is essential for studies of infectious pathogen tr ansmission from mother to fetus. Current models using amniotic membranes or thinner artificial membranes show significant leakage, suggesting disrupti on of tight junctions or the presence of gaps between syncytial units. Such disruption and discontinuity of trophoblast cultures are probably the resu lt of high stromal cell contamination, poor viability and lad; of prolifera tion in culture. We have successfully cultured confluent layers of tight-ju nctioned syncytium on semi-permeable insert membranes using highly viable p urified cytotrophoblasts and an alternating multiple seeding and differenti ation technique. Using criteria including transepithelial diffusion of high and low molecular weight substances, electrical resistance and directional secretion of the matrix metalloproteinase, MMP-9, we demonstrate that thes e cultures form effective and functional physical barriers that can be main tained for up to 1 month. (C) 2001 Harcourt Publishers Ltd.