The Effect of Acetylsalicylic Acid (ASA) on the Mechanical Properties of Breast Cancer Epithelial Cells

BACKGROUND

In most communities, the risk of developing breast cancer is increasing. By affecting the cyclooxygenase 1 and 2 (COX-1 and COX-2) enzymes and actin filaments, acetylsalicylic acid (Aspirin) has been shown to reduce the risk of breast cancer and prevent cell migration in both laboratory and clinical studies.

METHODS

The purpose of this study is to determine the mechanical properties of normal and cancerous breast tissue cells, as well as the short-term effect of aspirin on cancer cells. To this end, the mechanical properties and deformation of three cell types were investigated: healthy MCF-10 breast cells, MCF-7 breast cancer cells, and MCF-7 breast cancer cells treated with a 5 µM aspirin solution. Atomic Force Microscopy (AFM) was used to determine the mechanical properties of the cells. Cell deformation was analyzed in all groups, and Young's modulus was calculated using the Hertz model.

RESULT

According to the obtained data, cancer cells deformed at a rate half that of healthy cells. Nonetheless, when aspirin was used, cancer cells deformed similarly to healthy cells. Additionally, healthy cells' Young's modulus was calculated to be approximately three times that of cancer cells, which was placed closer to that of healthy cells by adding aspirin to Young's modulus.

CONCLUSION

Cell strength appears to have increased due to aspirin's intervention on actin filaments and cytoskeletons, and the mechanical properties of breast cancer cells have become more similar to those of normal cells. The likelihood of cell migration and metastasis decreases as cell strength increases.

A low-cost uniaxial cell stretcher for six parallel wells

Cells in the lungs, the heart, and numerous other organs, are constantly exposed to dynamic forces and deformations. To mimic these dynamic mechanical loading conditions and to study the resulting cellular responses such as morphological changes or the activation of biochemical signaling pathways, cells are typically seeded on flexible 2D substrates that are uniaxially or biaxially stretched. Here, we present an open-source cell stretcher built from parts of an Anet A8 3D printer. The cell stretcher is controlled by a fully programmable open-source software using GCode and Python. Up to six flexible optically clear substrates can be stretched simultaneously, allowing for comparative multi-batch biological studies including microscopic image analysis. The cell yield from the cell culture area of 4 cm² per substrate is sufficient for Western-blot protein analysis. As a proof-of-concept, we study the activation of the Yes-associated protein (YAP) mechanotransduction pathway in response to increased cytoskeletal tension induced by uniaxial stretching of epithelial cells. Our data support the previously observed activation of the YAP transcription pathway by stretch-induced increase in cytoskeletal tension and demonstrate the suitability of the cell stretcher to study complex mechano-biological processes.

Optomechanical measurement of the role of lamins in whole cell deformability

There is mounting evidence that the nuclear envelope, and particularly the lamina, plays a critical role in the mechanical and regulation properties of the cell and changes to the lamina can have implications for the physical properties of the whole cell. In this study we demonstrate that the optical stretcher can measure changes in the time-dependent mechanical properties of living cells with different levels of A-type lamin expression. Results from the optical stretcher shows a decrease in the deformability of cells as the levels of lamin A increases, for cells which grow both adherently and in suspension. Further detail can be probed by combining the optical stretcher with fluorescence microscopy to investigate the nuclear mechanical properties which show a larger decrease in deformability than for the whole cell.

Dynamic deformability of sickle red blood cells in microphysiological flow

In sickle cell disease (SCD), hemoglobin molecules polymerize intracellularly and lead to a cascade of events resulting in decreased deformability and increased adhesion of red blood cells (RBCs). Decreased deformability and increased adhesion of sickle RBCs lead to blood vessel occlusion (vaso-occlusion) in SCD patients. Here, we present a microfluidic approach integrated with a cell dimensioning algorithm to analyze dynamic deformability of adhered RBC at the single-cell level in controlled microphysiological flow. We measured and compared dynamic deformability and adhesion of healthy hemoglobin A (HbA) and homozygous sickle hemoglobin (HbS) containing RBCs in blood samples obtained from 24 subjects. We introduce a new parameter to assess deformability of RBCs: the dynamic deformability index (DDI), which is defined as the time-dependent change of the cell's aspect ratio in response to fluid flow shear stress. Our results show that DDI of HbS-containing RBCs were significantly lower compared to that of HbA-containing RBCs. Moreover, we observed subpopulations of HbS containing RBCs in terms of their dynamic deformability characteristics: deformable and non-deformable RBCs. Then, we tested blood samples from SCD patients and analyzed RBC adhesion and deformability at physiological and above physiological flow shear stresses. We observed significantly greater number of adhered non-deformable sickle RBCs than deformable sickle RBCs at flow shear stresses well above the physiological range, suggesting an interplay between dynamic deformability and increased adhesion of RBCs in vaso-occlusive events.

Experimental models for investigating intra-stromal migration of corneal keratocytes, fibroblasts and myofibroblasts

Following laser vision correction, corneal keratocytes must repopulate areas of cell loss by migrating through the intact corneal stroma, and this can impact corneal shape and transparency. In this study, we evaluate 3D culture models for simulating this process in vitro. Buttons (8 mm diameter) were first punched out of keratocyte populated compressed collagen matrices, exposed to a 3 mm diameter freeze injury, and cultured in serum-free media (basal media) or media supplemented with 10% FBS, TGFβ1 or PDGF BB. Following freeze injury, a region of cell death was observed in the center of the constructs. Although cells readily migrated on top of the matrices to cover the wound area, a limited amount of cell migration was observed within the constructs. We next developed a novel “sandwich” model, which better mimics the native lamellar architecture of the cornea. Using this model, significant migration was observed under all conditions studied. In both models, cells in TGFβ and 10% FBS developed stress fibers; whereas cells in PDGF were more dendritic. PDGF stimulated the most inter-lamellar migration in the sandwich construct. Overall, these models provide insights into the complex interplay between growth factors, cell mechanical phenotypes and the structural properties of the ECM.