A Label-Free Cell Sorting Approach to Highlight the Impact of Intratumoral Cellular Heterogeneity and Cancer Stem Cells on Response to Therapies

Abstract

Cancer stem cells play a crucial role in tumor initiation, metastasis, and resistance to treatment. Cellular heterogeneity and plasticity complicate the isolation of cancer stem cells. The impact of intra-tumor cellular heterogeneity using a label-free approach remains understudied in the context of treatment resistance. Here, we use the sedimentation field–flow fractionation technique to separate, without labeling, cell subpopulations of colorectal cancer cell lines and primary cultures according to their biophysical properties. One of the three sorted cell subpopulations exhibits characteristics of cancer stem cells, including high tumorigenicity in vivo and a higher frequency of tumor-initiating cells compared to the other subpopulations. Due to its chemoresistance, two- and three-dimensional in vitro chemosensitivity assays highlight the therapeutic relevance of this cancer stem cell subpopulation. Thus, our results reveal the major implication of intra-tumor cellular heterogeneity, including cancer stem cells in treatment resistance, thanks to our label-free cell sorting approach. This approach enables—by breaking down the tumor—the study the individualized response of each sorted tumor cell subpopulation and to identify chemoresistance, thus offering new perspectives for personalized therapy.

Sedimentation Field-Flow Fractionation: A Diagnostic Tool for Rapid Antimicrobial Susceptibility Testing

“…In the “Hyperlayer” elution mode, the elution time depends on the equilibrium position of bacteria inside the channel, conditioned by the opposition between the external field and the hydrodynamic forces . Indeed, the larger and less dense bacteria generate more elevation forces and are less sensitive to the field, thus concentrating in faster streamlines and being eluted first . The elution time also depends on the shape and stiffness or deformability of the bacteria.…”

“…50 Indeed, the larger and less dense bacteria generate more elevation forces and are less sensitive to the field, thus concentrating in faster streamlines and being eluted first. 51 The elution time also depends on the shape and stiffness or deformability of the bacteria. Thus, in order to carry out a rapid and specific monitoring of induced BEs, the optimal elution conditions were experimentally extracted from the field and flow matrix displayed in Table S4 and defined to be a flow rate of 1.6 mL/min and a multigravitational field of 20 g. Fractograms obtained with these conditions for the E. coli ATCC 25922, E. coli ATCC 35218, K. pneumoniae ATCC 700603, and P. aeruginosa ATCC 27853 strains are shown in Figure 2.…”

Field-Flow Fractionation in Molecular Biology and Biotechnology

“…SdFFF coupling with an ultra-high-frequency range dielectrophoresis fluidic biosensor was demonstrated to be suitable for cancer stem cell isolation from glioblastoma brain tumors. Cancer stem cells were separated based on orthogonal properties (size, density, shape, rigidity for FFF, and dielectrophoretic properties) with interesting perspectives for the diagnosis of complex tumor populations from the patient (Figure 9) [242,243]. Although SdFFF and GrFFF have been dominant in cell sorting, new variants, such as HF5 [252,253] and Dielectrophoresis FFF [27], have been proposed.…”