This study investigated the effects of BaCl2 adsorbed to polyethylene glycol (PEG) microspheres on human blood mononuclear cells (MN) co-cultured with breast cancer cell lines (MCF-7). The MCF-7 cells were obtained from the American Type Culture Collection and the blood mononuclear (MN) cells from volunteer donors. MN cells, MCF-7 cells and their co-culture (MN and MCF-7 cells) were pre-incubated for 24 h with or without 25 and 1000 pg L-1 BaCl2 (Ba25 and Ba1000), PEG microspheres or 25 and 1000 pg L-1 BaCl2 adsorbed to PEG microspheres (PEG-Ba25 and PEG-Ba1000). Rheological parameters and apoptosis were determined. Fluorescence microscopy and flow cytometry analyses revealed that BaCl2 was able to adsorb the PEG microspheres. The blood flow and viscosity curves were similar among the treatments. In general, apoptosis rates increased in co-cultured cells, co-cultured cells incubated with Ba25 and with PEG-Ba25, but the highest rates were observed in co-cultured cells incubated with PEG-Ba1000. In conclusion, BaCl2 adsorbed to PEG microspheres exhibited dose-dependent antitumor effects against human MCF-7 breast cancer cells co-cultured with MN cells, thereby offering a possible therapeutic alternative for treating this disease provided they are administered at very low concentrations.
Keywords: MCF-7 cells; PEG microsphere; apoptosis; barium chloride; mononuclear cells.