In vivo imaging of tumor growth after electrochemotherapy with cisplatin

Imaging methods can give both temporal and spatial dimensions to characterize the processes in progression of and/or treatment of specific disease Subcutaneous tumors can be cured after electrochemotherapy (ECT). Growth and reduction of tumors as a result of cytotoxic therapy can be followed by fluorescence video imaging directly on the same animal after treatment. Imaging of tumors should bring more information on the cellular effects of ECT. Green fluorescent protein (eGFP) expressing B16F10 and LPB tumors implanted in C57Bl/6 mice were treated with ECT with cisplatin. The growth or regression of the tumors was monitored either classically by using a caliper or by a manual definition of the region of interest where critical fluorescence levels were detected on the animals. A very good correlation between the two methods was observed. The eGFP mean fluorescence emission was only slightly affected by ECT with intravenously injected cisplatin. Ex vivo observations under a fluorescence microscope showed that eGFP was only detected on the outer layer of the tumor. No fluorescence was detected in the central part of the tumors, which were necrotic.