A. Blaschitz et al., Antibody reaction patterns in first trimester placenta: Implications for trophoblast isolation and purity screening, PLACENTA, 21(7), 2000, pp. 733-741
The aim of this immunohistochemical and cytochemical study was to select sp
ecific antibodies to establish an efficient purification protocol for first
trimester trophoblast and for subsequent purity screening of isolated trop
hoblast cells. The reactivity of antibodies to various cytokeratin filament
s, glycoprotein CD9, fibroblast specific antigen (FSA), common leukocyte an
tigen CD45RB and macrophage antigens CD163, CD68 and CD14 were studied on c
ryosections of placental tissue. Among the cytokeratins tested, cytokeratin
7 was the only keratin filament type, which was not expressed in placental
mesenchymal cells, but in all trophoblast subpopulations. Since anti-CD9,
in addition to mesenchymal cells, also strongly labels extravillous cytotro
phoblast cells, whereas the antibody to FSA only reacts with mesenchymal ce
lls, anti-FSA is suitable as a depletion antibody for mesenchymal cells. Am
ong the macrophage markers anti-CD163 was the most specific for Hofbauer ce
lls. CD45RB was expressed on maternal and fetal leukocytes as well as on Ho
fbauer cells. Isolated first trimester placental cell preparations that hav
e been collected from a density gradient contained up to 45 per cent non-tr
ophoblast cells. Immunocytochemistry using antibodies to CK7, FSA, vimentin
, CD45RB and CD163 demonstrated that subsequent immunodepletion with antibo
dies to CD45RB and FSA increased the purity of the trophoblast preparation
to greater than 98 per cent.
According to this study trophoblasts from first trimester placentae should
be identified by cytokeratin antibodies specific for the isoform 7. Purific
ation of isolated trophoblasts by density gradient alone does not result in
a sufficient degree of purity. (C) 2000 Harcourt Publishers Ltd.