Establishment of murine endothelial cell lines that develop angiosarcomas in vivo: brief demonstration of a proposed animal model for Kaposi's sarcoma.

We have reported previously that 100% of the incidence of malignant endotheliomas and angiosarcomas was developed in specific-pathogen-free BALB/c mice given s.c. injections of 1,2-dimethylhydrazine dihydrochloride. These tumors appeared selectively in the liver. In the present study, we have successfully established two cell lines in vitro (D10 and D14) from some of these tumors and have characterized the biological features of these lines. D10 and D14 have a 24- to 26-h doubling time and show a spindle formation in confluent monolayer cultures. The D10 line has a low capability of anchorage-independent growth in soft agar as well as less tumorigenicity in syngeneic mice. When as many as 10(7) D10 cells were injected s.c. into syngeneic mice, only one-half of the mice developed tumors composed of neoplastic endothelial cells with ample vascular lumina of various sizes. The histological appearance of this tumor resembled that of Kaposi's sarcoma as a human counterpart. The D14 line, in contrast, has a relatively high capability to grow in the soft agar culture. However, the tumor growth in vivo was less tumorigenic. None of the mice given injections of less than 10(6) D14 cells developed tumors. Although all of mice given injections of 10(7) D14 cells developed tumors, these tumors regressed completely until the 6th week after inoculation, suggesting that these cells were immunogenic in the transplantation assays using syngeneic mice. These lines may provide useful information for the study of cytological features of vascular tumors.