ACCUMULATION OF BORON IN MALIGNANT AND NORMAL-CELLS INCUBATED IN-VITRO WITH BORONOPHENYLALANINE, MERCAPTOBORANE OR BORIC-ACID

The short (<10 mu m) ranges of alpha and Li-7 particles produced durin g boron neutron capture therapy (BNCT) make the partitioning of the bo ronated drug within and without the cell of critical importance. The e valuation of the potential usefulness of a boron-containing substance for BNCT requires information about its intracellular accumulation. In the present report, an in vitro method is described for direct measur ement of intracellular boron based on rapid centrifugation of cells th rough a layer of mineral oil and silicon oil to strip away extracellul ar growth medium. The intracellular concentrations of boronophenylalan ine (BPA), mercaptoborane (BSH) and boric acid in malignant cells and in normal cells have been compared. The accumulation ratio is defined as the ratio of the intracellular to the extracellular boron concentra tion. Boric acid showed an accumulation ratio of 1 while the ratios fo r BSH and BPA were dependent on cell type and tended to be greater for BPA than for BSH in malignant but not in normal cells. (C) 1996 by Ra diation Research Society