Chemosensitivity testing with highly purified fresh human tumour cells with the MTT colorimetric assay

A major problem associated with the succinate dehydrogenase inhibition (SDI) test using tetrazolium dye (MTT) as a cancer chemosensitivity testing is the contamination of non-malignant cells in the tumour tissues. Highly purified fresh human tumour cells from 44 solid tumours and 24 malignant ascites were used for the MTT assay. The purity of tumour cells was greater than 90% after separation on Ficoll-Hypaque and Percoll discontinuous gradients. The OD570 obtained from tumour cells alone was higher than that from non-malignant cells. The chemosensitivity of tumour cells was distinct from that of non-malignant cells. Moreover, the chemosensitivity of highly purified tumour cells was also distinct from that of non-purified cells just separated from tumour tissues. 31 of the 68 patients had evaluable lesions, and received cancer chemotherapy according to the results of MTT assay using highly purified tumour cells. A clinical response was obtained in 10 of the 31 patients (response rate = 32.3%, 5 complete responses, 5 partial responses).