[Experimental studies on ascites tumor of human osteosarcoma in nude mice (author's transl)]

Six human osteosarcomas were transplanted subcutaneously in the back of nude mice and three of the six were found to be serially transplantable. Two of three transplantable solid tumors were called DOS tumor and KOS tumor. The 4th generation of DOS tumor and the 1st generation of KOS tumor grew to invade the peritoneum and tumor cells were spilt spontaneously into the abdominal cavity. These two cases were transformed to ascites tumor, called DOS-NM ascites tumor and KOS-NM ascites tumor. They were found to be serially transplantable by an intraperitoneal injection of free tumor cells (10-20 x 10(5) cells). DOS-NM and KOS-NM ascites tumor cells were analysed to have human karyotype and alkaline phosphatase activity. Ascites tumor cells were studied under light and electron microscopes. A large number of elongated and ballooned mitochondria were characteristically seen in the cytoplasm of two ascites tumor cells by electron microscope. Development of rough surfaced endoplasmic reticulum and Golgi's apparatus was poor, and no production of collagen fiber was seen in these materials. There is no report referring to ascites tumor of human osteosarcoma, therefore ascites tumor of osteosarcoma was made deliberately and the following results were obtained. 1) Several blocks of DOS tumor were implanted intraperitoneally into 5 nude mice, and only solid tumors grew in the abdominal cavity without ascites. 2) Minced DOS tumor was implanted subcutaneously close to the peritoneum and 2 out of 6 nude mice developed ascites tumor. 3) Cell suspension of DOS tumor was injected intraperitoneally and 3 out of 4 nude mice developed ascites tumors. As mentioned above, human osteosarcoma was successfully induced to ascites tumor (DOS-NM), which was established earlier compared with solid tumor (DOS). Characteristics of human osteosarcoma are easily examined with ascites tumor and in vivo screening test of anticancer drugs can be quantitatively done. Therefore ascites tumor is considered to be a valuable experimental model.