Nuclear accumulation of anthracyclines in the endothelium studied by bimodal imaging : fluorescence and Raman microscopy

Anthracycline antibiotics display genotoxic activity towards cancer cells but their clinical utility is limited by their cardiac and vascular toxicity. The aim of this study was to develop a Raman-based methodology to study the nuclear accumulation of anthracyclines in the endothelium. For this purpose bimodal confocal Raman and fluorescence imaging was used to monitor cellular composition changes as a result of anthracycline exposure on endothelial cells (EA.hy926), and nuclear drug accumulation, respectively. Simultaneously effects of anthracyclines on endothelium viability were investigated by caspases-3 and -7 and MTT assays. We demonstrated that nuclear accumulation of DOX and EDOX was similar; however, EDNR accumulated in endothelial nuclei at concentrations 10 times higher than DNR. In turn, epimers of DOX or DNR were both consistently less toxic on the endothelium as compared to their congeners as evidenced by MTT and caspase assays. In summary, bimodal Raman and fluorescence-based nucleus profiling proves to be a valuable tool to study structure-activity relationship of nuclear accumulation and toxicity of anthracyclines in endothelium

Spectroscopic studies of anthracyclines : structural characterization and in vitro tracking

A broad spectroscopic characterization, using ultraviolet–visible (UV–vis) and Fourier transform infrared absorption as well as Raman scattering, of two commonly used anthracyclines antibiotics (DOX) daunorubicin (DNR), their epimers (EDOX, EDNR) and ten selected analogs is presented. The paper serves as a comprehensive spectral library of UV–vis, IR and Raman spectra of anthracyclines in the solid state and in solution. The particular advantage of Raman spectroscopy for the measurement and analysis of individual antibiotics is demonstrated. Raman spectroscopy can be used to monitor the in vitro uptake and distribution of the drug in cells, using both 488 nm and 785 nm as source wavelengths, with submicrometer spatial resolution, although the cellular accumulation of the drug is different in each case. The high information content of Raman spectra allows studies of the drug-cell interactions, and so the method seems very suitable for monitoring drug uptake and mechanisms of interaction with cellular compartments at the subcellular level