3D Volumetric Mechanosensation of MCF7 Breast Cancer Spheroids in a Linear Stiffness Gradient GelAGE

Evaluation of allylated gelatin as a bioink supporting spontaneous spheroid formation of HepG2 cells

The spheroid culture system has gained significant attention as an effective in vitro model to mimic the in vivo microenvironment. Even though numerous studies were focused on developing spheroids, the structural organization of encapsulated cells within hydrogels remains a challenge. Allylated gelatin or GelAGE is used as a bioink due to its excellent physicochemical properties. In this study, GelAGE was evaluated for its capacity to induce spontaneous spheroid formation in encapsulated HepG2 cells. GelAGE was synthesized and characterized using 1HNMR spectroscopy and ninhydrin assay. Then the physicochemical and biological attributes of GelAGE hydrogel was examined. The results demonstrate that GelAGE has remarkable ability to induce the encapsulated cells to self-organize into spheroids.

Cellular elasticity in cancer: a review of altered biomechanical features

A large number of studies have shown that changes in biomechanical characteristics are an important indicator of tumor transformation in normal cells. Elastic deformation is one of the more studied biomechanical features of tumor cells, which plays an important role in tumourigenesis and development. Altered cell elasticity often brings many indications. This manuscript reviews the effects of altered cellular elasticity on cell characteristics, including adhesion viscosity, migration, proliferation, and differentiation elasticity and stiffness. Also, the physical factors that may affect cell elasticity, such as temperature, cell height, cell-viscosity, and aging, are summarized. Then, the effects of cell-matrix, cytoskeleton, in vitro culture medium, and cell-substrate with different three-dimensional structures on cell elasticity during cell tumorigenesis are outlined. Importantly, we summarize the current signaling pathways that may affect cellular elasticity, as well as tests for cellular elastic deformation. Finally, we summarize current hybrid materials: polymer-polymer, protein-protein, and protein-polymer hybrids, also, nano-delivery strategies that target cellular resilience and cases that are at least in clinical phase 1 trials. Overall, the behavior of cancer cell elasticity is modulated by biological, chemical, and physical changes, which in turn have the potential to alter cellular elasticity, and this may be an encouraging prediction for the future discovery of cancer therapies.

Label-free visualization and quantification of the drug-type-dependent response of tumor spheroids by dynamic optical coherence tomography

We demonstrate label-free dynamic optical coherence tomography (D-OCT)-based visualization and quantitative assessment of patterns of tumor spheroid response to three anti-cancer drugs. The study involved treating human breast adenocarcinoma (MCF-7 cell-line) with paclitaxel (PTX), tamoxifen citrate (TAM), and doxorubicin (DOX) at concentrations of 0 (control), 0.1, 1, and 10 µM for 1, 3, and 6 days. In addition, fluorescence microscopy imaging was performed for reference. The D-OCT imaging was performed using a custom-built OCT device. Two algorithms, namely logarithmic intensity variance (LIV) and late OCT correlation decay speed (OCDS[Formula: see text]) were used to visualize the tissue dynamics. The spheroids treated with 0.1 and 1 µM TAM appeared similar to the control spheroid, whereas those treated with 10 µM TAM had significant structural corruption and decreasing LIV and OCDS[Formula: see text] over treatment time. The spheroids treated with PTX had decreasing volumes and decrease of LIV and OCDS[Formula: see text] signals over time at most PTX concentrations. The spheroids treated with DOX had decreasing and increasing volumes over time at DOX concentrations of 1 and 10 µM, respectively. Meanwhile, the LIV and OCDS[Formula: see text] signals decreased over treatment time at all DOX concentrations. The D-OCT, particularly OCDS[Formula: see text], patterns were consistent with the fluorescence microscopic patterns. The diversity in the structural and D-OCT results among the drug types and among the concentrations are explained by the mechanisms of the drugs. The presented results suggest that D-OCT is useful for evaluating the difference in the tumor spheroid response to different drugs and it can be a useful tool for anti-cancer drug testing.