Metabolic imaging in tumours by means of bioluminescence

A bioluminescence technique involving single photon imaging was used to quantify the spatial distribution of the metabolites ATP, glucose and lactate in cryosections of various solid tumours and normal tissue. Each section was covered with an enzyme cocktail linking the metabolite in question to luciferase with light emission proportional to the metabolite concentration. The photons emitted are imaged directly through a microscope and an imaging photon counting system. In some cases, good agreement was observed between the distribution of relatively high concentrations of ATP and glucose in viable cell regions of the periphery, while the reverse was seen in more necrotic tumour centres with comparatively high lactate levels. In general, lactate was distributed more diffusely over the sections while ATP was more highly localised and glucose assumed an intermediate pattern. In contrast to the large degree of heterogeneity seen in tumours, distribution patterns of metabolites were much more homogeneous in normal tissue, such as heart muscle. Mean values for metabolite levels in cryosections using bioluminescence are in good agreement with those obtained from the same tumour by conventional methods.