Probing Hexaminolevulinate Mediated PpIX Fluorescence in Cancer Cell Suspensions in the Presence of Chemical Adjuvants

Exogenous administration of hexaminolevulinate (HAL) induces fluorescent protoporphyrin IX (PpIX) accumulation preferentially in cancer cells. However, the PpIX fluorescence intensities between noncancer and cancer cells are highly variable. The contrast between cancer and noncancer cells may be insufficient to reliably discriminate, especially at the single cell level in cancer diagnostics. This study examines the use of the chemical adjuvants dimethylsulphoxide (DMSO) or deferoxamine (DFO) to enhance the HAL induced PpIX accumulation in cancer cells. Our results showed that in some of the incubation conditions tested, the addition of DFO with HAL significantly increased PpIX 21 fluorescence of adherent monolayer cancer cells, but this was never the case for cells in suspension. Permeabilisation with DMSO did not increase PpIX fluorescence. Cell-to-cell interaction may well play an important role in the PpIX accumulation when suspended cells are treated in HAL and adjuvant chemicals.