Failure of human myeloma cells to heterotransplant into the brain of athymic rats.

Sixty-four separate intracranial inoculations of bone marrow cells obtained from 26 patients with human myeloma were performed and the animals were kept under observation for 9-10 months. Samples were obtained from a heterogenous group of patients with diverse types of paraprotein production, clinical status, and response to treatment. Inocula size ranged from 3.5 x 10(5) nucleated cells to about 2 x 10(7), while the percentage of plasma cells varied from nondetectable to 90%. Only one animal (of 2) injected with an aliquot of the bone marrow aspirate from a patient developed a small, clinically undetectable tumor, noticed at the end of the observation period. No other animal developed tumors. Thus, our studies indicate that the intracerebral inoculation of human myeloma cells may not be a profitable means of establishing additional human myeloma cell lines.