Autologous bone marrow transplants for solid
tumor treatment are severely limited by the potential presence of
residual cancer cells in the reinfused bone marrow and can lead to future
tumor recurrence. This article presents a novel method of removing
carcinoma cells from bone marrow with contaminating
cancer cells. This method is based on our previous studies demonstrating that
carcinoma cells have a higher uptake of lipophilic
cations such as
rhodamine 123 than their normal epithelial counterparts. When the relative differences in
rhodamine 123 uptake are quantified,
carcinoma cell lines demonstrated a 7.4-21 times greater uptake of
rhodamine 123 than normal mouse bone marrow cells. More important, when normal bone marrow cells and
carcinoma cell lines are mixed to simulate
carcinoma-contaminated bone marrow, individual cell populations continue to exhibit characteristic and identifiable relative differences (10-20 times) in
rhodamine 123 uptake. Differential sorting of bone marrow/
carcinoma cell mixtures with respect to
rhodamine 123 fluorescence intensity resulted in the removal of 95-99% of the "contaminating
carcinoma cells." The recovered bone marrow cells were fully viable as ascertained by their ability to form splenic colonies. In our preliminary experiments, sorted bone marrow cells transplanted into lethally irradiated C57BL6 mice allowed the mice to survive for more than 8 months. In light of these promising results, we propose that lipophilic
cations may play a role in the purification of autologous bone marrow used in transplants for patients with advanced solid
tumors.