Microcells development and endocytosis ability morphological and quantitative characterization in HeLa cancer cells

Determination of endocytotic ability of cancer cells could improve tumor treatment results. The aim of this study was to investigate morphological aspects of development in HeLa (Henrietta Lacks cervical cancer cells) microcells and to quantitatively estimate the endocytotic capability of these cells. The HeLa cell line was maintained at 37 °C in DMEM medium 3-4 days. Cell samples were supravitally stained with different markers (acridine orange, water soluble CdSe/ZnS nanoparticles, Indian ink, carmine red). Cell photographs were taken using a Leica DM6000B microscope connected to a DFC 490 digital camera. Microscope images were analyzed and measured with an IPP 5.0 image analysis program. Geometrical and photometrical measurements were obtained in order to distinguish particular cell classes in HeLa cell line subpopulations. We found that different markers accumulate more in specific morphological states of cancer cells. An increased mean cell fluorescence intensity suggested greater endocytosis capability in early microcell development stages. We observed water soluble CdSe/ZnS nanoparticle accumulation and cell surface binding in all cell classes, but significant enhancement of fluorescence intensity was observed in microcells. Although we used different sizes of nanoparticles with different fluorescence emission spectra in our experiments, we acquired fluorescent emission spectra very similar to supravital staining with red and green nanoparticles, suggesting that nanoparticle spectral properties are determined by mutual binding with cell structures. All supravital staining methods (Indian ink, carmine red, acridine orange (AO), red and green CdSe/ZnS nanoparticles) allowed determination of different endocytotic capabilities in various HeLa cancer cell classes. Measured fluorescence intensities and degrees of endocytosis are highly correlated, allowing characterization of endocytosis ability of different cancer cell classes.