Pleuro-pulmonary tumours detected by clinical and chest X-ray analyses in rats transplanted with mesothelioma cells.

New strategies for cancer therapy must be developed, especially in severe neoplasms such as malignant pleural mesothelioma. Animal models of cancer, as close as possible to the human situation, are needed to investigate novel therapeutical approaches. Orthotopic transplantation of cancer cells is then relevant and efforts should be made to follow up tumour evolution in animals. In the present study, we developed a method for the orthotopic growth of mesothelioma cells in the pleural cavity of Fischer 344 and nude rats, along with a procedure for clinical survey. Two mesothelioma cell lines, of rat and human origin, were inoculated by transthoracic puncture. Body weight determination and chest X-ray analyses permitted the follow-up of tumour evolution by identifying different stages. Autopsies showed that tumours localized on the whole pleural cavity (diaphragm, parietal pleura), mediastinum and pericardium. Tumour morphology and antigenic characteristics were consistent with those of the inoculated cells and were similar in both types of rats inoculated with the same cell type. These results demonstrate that mesothelioma formation in rats can be followed up by clinical and radiographic survey after gentle intrathoracic inoculation of mesothelioma cells, thus allowing the definition of stages of interest for further experimental trials.