Christopher Mark Waters, PhD, ATSF

The Waters lab focuses on mechanobiology and acute lung injury. Patients with acute respiratory distress syndrome (ARDS) are placed on mechanical ventilators to improve oxygenation, but the ventilator may cause additional injury to the lungs due to either overdistention or airway collapse and reopening. Clinical trials have demonstrated a substantial reduction in mortality in ARDS patients when ventilation strategies are used that reduce overdistention (lower tidal volumes) and minimize airway collapse and reopening (positive end expiratory pressure). The lung is a mechanically dynamic organ, and cells in the lung are subjected to shear stress due to fluid flow, tensile and compressive forces due to respiratory motion, and normal forces due to vascular or airway pressure. High tidal volume mechanical ventilation in injured lungs induces mechanical stresses that increase injury to the lung epithelium, stimulate inflammatory responses, and decrease repair mechanisms. We are focusing on the mechanisms by which mechanical forces contribute to lung injury, inhibit wound healing of lung epithelial cells, and stimulate inflammation. We are examining signaling pathways related to injury and repair (CXCL12/CXCR4, ASK1, FAK, Rho GTPases), cell migration and wound healing, inflammasome activation, cytoskeletal remodeling, stimulation of reactive oxygen species, cytokine secretion, and regional variations in cellular tension. In addition we are examining lung injury in vivo and the effects of exposure to high levels of oxygen (hyperoxia). My research seeks to identify the levels of mechanical forces and the types of lung injury that cells experience in vivo, to develop in vitro models to evaluate cellular responses, to identify mechanisms by which mechanical forces are transduced into biological signals, and to develop approaches to reduce lung injury.

Current techniques:

• Lung injury models in mice and rats.

• Targeted gene deletion models.

• Mechanically ventilated mice and rats; measurement of lung mechanics (resistance and compliance).

• Hyperoxia exposure (mice, cells).

• Isolation and culture of airway and alveolar epithelial cells, lung vascular endothelial cells, and brain microvascular endothelial cells.

• Application of cyclic mechanical strain to cells.

• Atomic force microscopy to determine distribution of mechanical properties in migrating cells.

• Wound healing assays.

• Spectrophotometry and fluorescence microscopy to measure reactive oxygen species production.

• Application of fluid shear stress to cells - flow chambers, cell columns.

• Evaluation of barrier function/permeability of cell monolayers - cell column (on line), transwell culture.

• Transepithelial electrical resistance measurements (including the ECIS system).

• Western analysis to evaluate signaling pathways and cytoskeletal and focal adhesion levels.

• Confocal fluorescence microscopy to visualize cell cytoskeleton (f-actin, microtubules), focal adhesions, integrins, junctional assembly.