Biology subjects

Gnanachandran, K.

Publications and source records attributed to Gnanachandran, K..

3 recordsLinked to original sources

bioRxiv2023

Multiscale Rheology of Aging Cancer Spheroids

Cancer spheroids offer a valuable experimental model that mimics the complexity and heterogeneity of solid tumors. Characterizing their mechanical response is crucial for understanding tumor development, progression, and drug response. Currently, whole live spheroids are analyzed primarily using image analysis, which is challenging, requires extended incubation times, and has limited imaging depth. Here, we present a new label-free approach for characterizing sub-superficial structures of bladder cancer spheroids and measuring their mechanical response at three distinct stages of cancer progression. We study the microrheological changes induced by aging at the cellular and cluster levels by conducting a multi-physics characterization and modeling approach. We find that spheroids exhibit viscoelastic behavior that can be described by fractional models. We show that spheroids are mechanically heterogeneous, with strong depth and time-dependent variations associated with evolving structural features. Our approach opens new possibilities to study 3D in vitro models, paving the way for the discovery of novel and more precise procedure in cancer diagnosis based on the use of mechanomarkers.

biophysics↗

bioRxiv2023

Reliable, standardized measurements for cell mechanical properties

Atomic force microscopy (AFM) has become indispensable for studying biological and medical samples. More than two decades of experiments have revealed that cancer cells are softer than healthy cells (for measured cells cultured on stiff substrates). The softness or, more precisely, the larger deformability of cancer cells, primarily independent of cancer types, could be used as a sensitive marker of pathological changes. The wide application of biomechanics in clinics would require designing instruments with specific calibration, data collection, and analysis procedures. For these reasons, such development is, at present, still very limited, hampering the clinical exploitation of mechanical measurements. Here, we propose a standardized operational protocol (SOP), developed within the EU ITN network Phys2BioMed, which allows the detection of the biomechanical properties of living cancer cells regardless of the nanoindentation instruments used (AFMs and other indenters) and the laboratory involved in the research. We standardized the cell cultures, AFM calibration, measurements, and data analysis. This effort resulted in a step-by-step SOP for cell cultures, instrument calibration, measurements, and data analysis, leading to the concordance of the results (Youngs modulus) measured among the six EU laboratories involved. Our results highlight the importance of the SOP in obtaining a reproducible mechanical characterization of cancer cells and paving the way toward exploiting biomechanics for diagnostic purposes in clinics.

biophysics↗

bioRxiv2022

Nanomechanical and microrheological properties of bladder cancer cells at cellular and spheroid levels

Cancer progression is associated with changes in cell mechanical and rheological properties that could be probed by atomic force microscopy (AFM). In this study, we applied AFM to measure elastic (by compressing the cells) and viscoelastic (by applying shear stress) properties of bladder cancers in relation to their culture morphology (in single cells, cell monolayers, and spheroids). Three different cell lines, HCV29 (non-malignant cell cancer of ureter), HT1376 (grade III bladder carcinoma), T24 (grade IV transitional cell carcinoma), were investigated. Nanoindentation measurements only differentiate between non-malignant and cancer cells, but it is difficult to distinguish between specific bladder cancers. By applying microrheological measurements, we confirm that non-malignant cells are more rigid than cancer cells but more importantly, it was possible to differentiate between two cancerous cell lines, regardless of the culture conditions. As each of them is characterized by a distinct actin filament network inside the cell, we showed that actin filaments are a key element in defining the rheological properties of spheroids originating from cells having thick actin bundles. Our results showed that HCV29 cells are more rigid than the studied cancer cells, indicating that normal cells are resistant to compressive and shear forces. Therefore, we conclude that cell mechanical and rheological properties may serve as a biophysical marker to distinguish normal and cancer cells of different malignancies.

biophysics↗