Keratinocytes, mastocytoma cells, wild-type osteosarcoma 143B and mutant DNA-deficient osteosarcoma 1436rho cells were studied by fluorescence imaging at 360nm and 450nm excitation. With the vital probe Mitotracker green, real-time visualization was possible in the wild-type osteosarcoma, while in the DNA-deficient cells the accumulation of 30 or more scans was required. In the rho-type cells, broad tentacle-like processes appeared which contained mitochondria-shaped granules loaded with Mitotracker green. Generally two mitochondrial morphologies were seen: filamentous or globoid. NADH response was triggered by a glucose challenge. Within seconds, the mitochondria responded by increased NADH fluorescence which appeared first in a few scattered clusters, and very soon spread to the rest of the mitochondria with increased intensity. Thus despite the low quantum yield of the NADH fluorescence and the rapidity of the response, it appears possible to image the fluorescence increase and its spread within and throughout clusters at the limit of sensitivity. It identifies the osteosarcoma cell as particularly suitable for the study of mitochondrial metabolic activation. The method's further development by application of Fourier interferometry for fluorescence excitation imaging will be discussed. These osteosarcoma cells are a good model for the extension of the method in diagnostics of malignant cells, prognostics and potentially for therapy.
