Growth of human head and neck squamous cell carcinoma stem cells in agarose.

An in vitro human tumor cell assay was used in an attempt to culture head and neck tumors from patients with squamous cell carcinomas. Initially, specimens from nine head and neck tumors were disaggregated by mechanical methods and assayed in soft agar. Five of nine tumors grew in the soft-agar system yielding a cloning success rate of 56%. Plating of 5 X 10(5) cells resulted in 12 to 255 colonies per plate after 21 days in culture, with a cloning efficiency between 0.002% and 0.08%. Recently, the authors replaced the agar with an agarose culture matrix. Of 10 specimens with positive pathology, 9 have shown colony growth (greater than 20 cells). Cloning efficiency in agarose improved approximately 2-fold. Morphologic assessment of tumor colonies in culture showed the same characteristics as those of the original tumor. Overall success rate of growing head and neck tumors in agar and agarose has been 14 of 19 patients (74%). The development of a soft agarose assay for head and neck tumor cells should provide an in vitro technique for predicting in vivo response to anticancer drugs and other therapeutic modalities such as radiotherapy and hyperthermia.