Label-free drug response evaluation of human derived tumor spheroids using three-dimensional dynamic optical coherence tomography

This study aims at demonstrating label -free drug -response -patterns assessment of different tumor spheroids and drug types by dynamic optical coherence tomography (D-OCT). The study involved human breast cancer (MCF-7) and colon cancer (HT -29) spheroids. The MCF-7 and HT -29 spheroids were treated with paclitaxel (Taxol; PTX) and the active metabolite of irinotecan SN-38, respectively. The drugs were applied with 0 (control), 0.1, 1, and 10 mu M concentrations and the treatment durations were 1, 3, and 6 days. A swept -source OCT microscope equipped with a repeated raster scanning protocol was used to scan the spheroids. Logarithmic intensity variance (LIV) and late OCT correlation decay speed (OCDSl) algorithms were used to visualize the tumor spheroid dynamics. LIV and OCDSl images visualized different response patterns of the two types of spheroids. In addition, spheroid morphology, LIV, and OCDSl quantification showed different time -courses among the spheroid and drug types. These results may indicate different action mechanisms of the drugs. The results showed the feasibility of D-OCT for the evaluation of drug response patterns of different cell spheroids and drug types and suggest that D-OCT can perform anti -cancer drug testing.