Background. Angiogenesis studies are limited by the clinical relevance of laboratory model systems. We developed a new method for measuring dead microvascular (MV) cells in clinical tissue, fluid and blood specimens, and applied this system to make several potentially novel observations relating to cancer pharmacology.
Methods. Dead MV cells tend to have a hyperchromatic, refractile quality, further enhanced during the process of staining with Fast Green and counterstaining with either haematoxylin–eosin or Wright–Giemsa. We used this system to quantify the relative degree of direct antitumour versus anti-MV effects of cisplatin, erlotinib, imatinib, sorafenib, sunitinib, gefitinib and bevacizumab.
Results. Bevacizumab had striking anti-MV effects and minimal antitumour effects; cisplatin had striking antitumour effects and minimal anti-MV effects. The `nib' drugs had mixed antitumour and anti-MV effects. Anti-MV effects of erlotinib and gefitinib were equal to those of sunitinib and sorafenib. There was no detectable VEGF in culture medium without cells; tumour cells secreted copious VEGF, reduced to undetectable levels by bevacizumab, greatly reduced by cytotoxic levels of cisplatin + anguidine, and variably reduced by DMSO and/or ethanol. We observed anti-MV additivity between bevacizumab and other drugs on an individual patient basis. Peripheral blood specimens had numerous MV cells which were strikingly visualized for quantification with public domain image analysis software using bevacizumab essentially as an imaging reagent.
Conclusions. This system could be adapted for simple, inexpensive and sensitive/specific detection of tissue and circulating MV cells in a variety of neoplastic and non-neoplastic conditions, and for drug development and individualized cancer treatment.