Dependence of fibroblast autofluorescence properties on normal and transformed conditions, role of the metabolic activity

The dependence of autofluorescence properties on the metabolic and function al engagement and on the transformation condition was studied on single cel ls. Normal Galliera rat fibroblasts at low subculture passage (cell strain) , at high subculture passage (stabilized cell line), and transformed cell l ine derived from a rat sarcoma were used as a cell model. The study was per formed by microspectrofluorometric and fluorescence imaging technique, The autofluorescence properties of cells were studied by excitation at two wave lengths, namely 366 nm and 436 nm, that are known to favor the emission of different fluorophores, Spectral shape analysis indicated that under excita tion at 366 nn autofluorescence is ascribable mainly to coenzyme molecules, particularly to reduced pyridine nucleotides, while under excitation at 43 6 nm, flavin and lipopigment emission is favored. The energetic metabolic e ngagement of the different cell lines was analyzed in terms both of paramet ers related to anaerobic-aerobic pathways (biochemical assay) and of mitoch ondrial features (supravital cytometry), The results showed that the cell s train and the stabilized and transformed cell lines can be distinguished fr om one another on the basis of both overall fluorescence intensity and the relative contributions of spectral components. These findings indicated a r elationship between autofluorescence properties and energetic metabolism en gagement of the cells that, in turn, is dependent on the proliferative acti vity and the transformed condition of the cells. In that it is a direct exp ression of the energetic metabolic engagement, autofluorescence can be assu med as an intrinsic parameter of the cell biological condition, suitable fo r diagnostic purposes.