Enrichment of cancer stem-like cells by controlling oxygen, glucose and fluid shear stress in a microfluidic spheroid culture device

Abstract

Current chemotherapies can often kill fast-growing cancer cells but are ineffective in destroying cancer stem cells (CSCs). This study aimed to investigate the effect of in vitro cell culture conditions on the features of lung adenocarcinoma cells (represented by A549, non-small cell type (NSCLC), cell lines) and the induction of cancer stem-like cells. For this purpose, a microfluidic system containing U-shaped arrays was designed and numerically optimized. This system was used for the three-dimensional culture of cells under a continuous laminar flow of culture medium. Numerical simulations were also performed to estimate the quiescent and necrotic zones inside the spheroids and the fluid shear stress on the cultured spheroids. Moreover, the effects of culture medium flow rate, oxygen and glucose concentrations and anoikis phenomenon on the number of CD90+ cells and expression of stemness, epithelial-mesenchymal transition (EMT) and ATP-binding cassette (ABC)-transporters genes were investigated. The results showed that all these parameters substantially affected the enrichment of A549 cancer stem-like cells. We also investigated the effect of the CSC enrichment method, i.e., shear stress and oxygen and glucose concentrations, on resistance to cisplatin treatment. Increasing shear stress and glucose concentration and decreasing oxygen concentration led to a sharp increase in chemoresistance of cells. Interestingly, changing oxygen concentration was more significant than changing the other factors. The results of this paper can be helpful for the effective enrichment of CSCs by adjusting in vitro culture conditions.