68
Another method implements the TransWell®, a customized two-compartment
system for growing cells. Two vials are inserted one inside the other. A semi
permeable membrane closes the flat bottom of the inner vial. In transplacental
studies, the inner vial represents the fetal vessel, the outer the maternal venous
sinus. Two types of throphoblast-derived cells could develop as a confluent
monolayer on the flat bottom of a TransWell®: the stabilized cell lines are
representative of the labyrinthine trophoblast cells of rat, and those representative of
third-trimester trophoblasts, derived from a human choriocarcinoma. When grown
as a monolayer, the trophoblast cells do not form syncytium, only the tight junctions
are well developed. It is also possible to grow them in multilayer (TransWell®
system B). In this case, the bilayer develops after 5 days, and 10% of cells are
multilayered at day 7 of culture, with initial syncytium. The system was optimized
to study the transport of nanomaterials across the placenta (Bode et al. 2006;
Cartwright et al. 2012; Sood et al. 2011). The presence of a monostratified cell layer
with tight junctions has been confirmed by protein staining and by the measurement
of transepithelial electric resistance, higher than 30 Watt per square centimeter
(Cartwright et al. 2012). The monolayer can be permeable to nanomaterials,
allowing a mono- or bi-directional crossing, or can accumulate several compounds,
unable to cross the barrier. The absence of nanomaterials in the outer compartment
(the “fetal” one) does not exclude the presence of dissolution products. On the
bottom of the outer chamber, layers of other types of cells, such as stem cells,
precursor, and fibroblasts, simulate the fetal tissues (Fig. 3.6).
Fig. 3.5 Schema of the perfused placenta ex vivo. The placenta, expelled at the end of the pregnancy, is perfused through catheters, inserted in the chorionic artery and vein, that represent the
fetal district, and in the villous space, at the maternal surface. The flux, from the maternal district
to the fetal and vice-versa, is constant, as are the pressure, temperature, humidity, pH, and dissolved gases
Abbreviations: CO 2 : carbon dioxide; N 2 : gasous nitrogen, °C: centigrades
A. G. Cattaneo
Another method implements the TransWell®, a customized two-compartment
system for growing cells. Two vials are inserted one inside the other. A semi
permeable membrane closes the flat bottom of the inner vial. In transplacental
studies, the inner vial represents the fetal vessel, the outer the maternal venous
sinus. Two types of throphoblast-derived cells could develop as a confluent
monolayer on the flat bottom of a TransWell®: the stabilized cell lines are
representative of the labyrinthine trophoblast cells of rat, and those representative of
third-trimester trophoblasts, derived from a human choriocarcinoma. When grown
as a monolayer, the trophoblast cells do not form syncytium, only the tight junctions
are well developed. It is also possible to grow them in multilayer (TransWell®
system B). In this case, the bilayer develops after 5 days, and 10% of cells are
multilayered at day 7 of culture, with initial syncytium. The system was optimized
to study the transport of nanomaterials across the placenta (Bode et al. 2006;
Cartwright et al. 2012; Sood et al. 2011). The presence of a monostratified cell layer
with tight junctions has been confirmed by protein staining and by the measurement
of transepithelial electric resistance, higher than 30 Watt per square centimeter
(Cartwright et al. 2012). The monolayer can be permeable to nanomaterials,
allowing a mono- or bi-directional crossing, or can accumulate several compounds,
unable to cross the barrier. The absence of nanomaterials in the outer compartment
(the “fetal” one) does not exclude the presence of dissolution products. On the
bottom of the outer chamber, layers of other types of cells, such as stem cells,
precursor, and fibroblasts, simulate the fetal tissues (Fig. 3.6).
Fig. 3.5 Schema of the perfused placenta ex vivo. The placenta, expelled at the end of the pregnancy, is perfused through catheters, inserted in the chorionic artery and vein, that represent the
fetal district, and in the villous space, at the maternal surface. The flux, from the maternal district
to the fetal and vice-versa, is constant, as are the pressure, temperature, humidity, pH, and dissolved gases
Abbreviations: CO 2 : carbon dioxide; N 2 : gasous nitrogen, °C: centigrades
A. G. Cattaneo