The separation of a mixture of bone marrow stem cells from tumor cells: an essential step for autologous bone marrow transplantation

KHT tumor cells were mixed with mouse bone marrow to simulate a sample of bone marrow containing metastatic tumor cells. This mixture was separated into a bone marrow fraction and a tumor cell fraction by centrifugal elutriation. Elutriation did not change the transplantability of the bone marrow stem cells as measured by a spleen colony assay and an in vitro erythroid burst forming unit assay. The tumorogenicity of the KHT cells was similarly unaffected by elutriation. The data showed that bone marrow cells could be purified to less than 1 tumor cell in more than 106 bone marrow cells. Therefore, purification of bone marrow removed prior to lethal radiation-drug combined therapy for subsequent autologous transplantation appears to be feasible using modifications of this method if similar physical differences between human metastatic tumor cells and human bone marrow cells exist. This possibility is presently being explored