Marmoset monkey trophoblastic tissue growth and matrix metalloproteinase secretion in culture

Marmoset monkey blastocysts maintained in culture produced trophoblastic ve sicles up to 4 mm in diameter that were subdivided into fragments and subcu ltured to produce new vesicles. These tissues are composed of an outer laye r of trophoblast-like cells and an inner layer of endoderm-like cells, and resemble a blastocyst wall. When such vesicles were cultured in serum-free medium for 14 days, they increased in size but there was no significant dif ference in their protein content at the end of culture. The proliferation i ndex, measured by BrdU incorporation, varied considerably within and betwee n vesicles. The purpose of this investigation was to determine which matrix metalloproteinases are secreted by marmoset monkey trophoblastic tissue in vitro, and the effect Of extracellular laminin on this secretion. It was d etermined by zymography that the vesicles secreted matrix metalloproteinase 2, but not matrix metalloproteinase 9, and that matrix metalloproteinase 2 was secreted as the proenzyme (72 kDa). Matrix metalloproteinases 1, 3 and 7 were not detectable in the culture medium. The addition of laminin (5-20 mu g ml(-1)), either as a substrate or in solution in the medium, did not have a consistent effect on matrix metalloproteinase 2 secretion during the culture period. The vesicles were found to express both matrix metalloprot einases 2 and 9 in both types of cell when examined by immunohistochemistry . The expression of matrix metalloproteinase 9 in the vesicles, but the abs ence of its secretion, indicates that specific factors, possibly of endomet rial origin, may be required for inducing secretion.