Application of a Flow-Induced Stress Wave and Investigation of Associated Injuries on Cell Monolayers Using a Parallel Plate Flow Chamber

Characterization of MXene as a Cancer Photothermal Agent Under Physiological Conditions

A growing interest has recently emerged in the use of nanomaterials in medical applications. Nanomaterials, such as MXene, have unique properties due to their 2D ultra-thin structure, which is potentially useful in cancer photothermal therapy. To be most effective, photothermal agents need to be internalized by the cancer cells. In this study, MXene was fabricated using chemical reactions and tested as a photothermal agent on MDA-231 breast cancer cells under static and physiological conditions. Fluid shear stress (∼0.1 Dyn/cm2) was applied using a perfusion system to mimic the physiological tumor microenvironment. The uptake of MXene was analyzed under fluid flow compared to static culture using confocal microscopy, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and transmission electron microscopy (TEM). Furthermore, a viability assay was used to assess cell’s survival after exposing the treated cells to photothermal laser at different power densities and durations. We showed that when incubated with cancer cells, 2D MXene nanoparticles were successfully internalized into the cells resulting in increased intracellular temperatures when exposed to NIR laser. Interestingly, dynamic culture alone did not result in a significant increase in uptake suggesting the need for surface modifications for enhanced cellular uptake under shear stress.

Dexamethasone and transdehydroandrosterone significantly reduce pulmonary epithelial cell injuries associated with mechanical ventilation

Many patients who suffer from pulmonary diseases cannot inflate their lungs normally, as they need mechanical ventilation (MV) to assist them. The stress associated with MV can damage the delicate epithelium in small airways and alveoli, which can cause complications resulting in ventilation-induced lung injuries (VILIs) in many cases, especially in patients with acute respiratory distress syndrome (ARDS). Therefore, efforts were directed to develop safe modes for MV. In our work, we propose a different approach to decrease injuries of epithelial cells (EpCs) upon MV. We alter EpCs' cytoskeletal structure to increase their survival rate during airway reopening conditions associated with MV. We tested two anti-inflammatory drugs dexamethasone (DEX) and transdehydroandrosterone (DHEA) to alter the cytoskeleton. Cultured rat L2 alveolar EpCs were exposed to airway reopening conditions using a parallel-plate perfusion chamber. Cells were exposed to a single bubble propagation to simulate stresses associated with mechanical ventilation in both control and study groups. Cellular injury and cytoskeleton reorganization were assessed via fluorescence microscopy, whereas cell topography was studied via atomic force microscopy (AFM). Our results indicate that culturing cells in media, DEX solution, or DHEA solution did not lead to cell death (static cultures). Bubble flows caused significant cell injury. Preexposure to DEX or DHEA decreased cell death significantly. The AFM verified alteration of cell mechanics due to actin fiber depolymerization. These results suggest potential beneficial effects of DEX and DHEA for ARDS treatment for patients with COVID-19. They are also critical for VILIs and applicable to future clinical studies.NEW & NOTEWORTHY Preexposure of cultured cells to either dexamethasone or transdehydroandrosterone significantly decreases cellular injuries associated with mechanical ventilation due to their ability to alter the cell mechanics. This is an alternative protective method against VILIs instead of common methods that rely on modification of mechanical ventilator modes.