Imaging of whole tumor cut sections using a novel scanning beam confocal fluorescence MACROscope

Hypoxia caused by inadequate structure and function of the tumor vasculature has been found to negatively determine the prognosis of cancer patients. Hence, understanding the biological basis of tumor hypoxia is of significant clinical interest. To study solid tumor microenvironments in sufficient detail, large areas (several mm in diameter) need to be imaged at mm resolutions. We have used a novel confocal scanning laser MACROscope® (CSLM) capable of acquiring images over fields of view up to 2 cm32 cm. To demonstrate its performance, frozen sections from a cervical carcinoma xenograft were triple labeled for tissue hypoxia, blood vessels and hypoxiainducible transcription factor 1 alpha (HIF-1?), imaged using the CSLM and compared to images obtained using a standard epifluorescence microscope imaging system. The results indicate that the CSLM is a useful instrument for imaging tissue-based fluorescence at resolutions comparable to standard low-power microscope objectives.