Characteristic growth of human choriocarcinoma xenografts in nude mice

In order to investigate the mechanisms and regulation of trophoblast vessel invasion, we established a model using malignant trophoblast cells grown i n nude mice. The human choriocarcinoma cell line Jeg-3 established fast-gro wing tumours within 2 weeks after subcutaneous injection into nude mice. In terestingly, instead of neoangiogenesis the tumours were characterized by l arge blood-filled lacunae. Staining for hCG-beta and for mouse panendotheli al antigen revealed that the majority of the lacunae were lined by trophobl ast cells. The blood supply of the lacunae resulted from invasion of the ch oriocarcinoma cells into the host vessels at the junctional zone between tu mour and mouse tissue. These large blood-filled lacunae led to a much faste r expansion of tumours with less necrotic areas compared to tumours of non- trophoblastic origin (Hec-1A and HeLa), which revealed neovascularization. Jeg-3 choriocarcinoma cells eroded host vessels and replaced the endothelia l lining in a similar way to trophoblast cells during the establishment of a haemochorial placenta. This model can be useful in investigating the cell biological mechanisms of trophoblast vessel invasion and replacement of th e endothelium by trophoblast cells. (C) 1999 Harcourt Publishers Ltd.