High-throughput optical screening of cellular mechanotransduction

Authors:  J. L. Compton, J. C. Luo, H. Ma, E. Botvinick and V. Venugopalan
Journal:  Nature Photonics (published online August 3, 2014)

SUMMARY
Many pathological conditions including hypertension, osteoarthritis, and tumor metastasis have been linked to the dysregulation of biochemical pathways that modulate cell behavior based on its local mechanical microenvironment. Unfortunately, no methods exist that can rapidly identify molecules that can interfere with these cellular mechanotransduction pathways. The authors introduce an optical platform that combines pulsed laser irradiation and dynamic fluorescence imaging for rapid, high-throughput screening of exogenous molecules that affect cellular mechanotransduction.  The method initiates mechanotransduction in adherent cells using single laser-microbeam generated microcavitation bubbles without requiring flow chambers or microfluidics.  These microcavitation bubbles expose adherent cells to a microtsunami, a transient microscale burst of hydrodynamic shear stress, which can stimulate primary human endothelial cells over areas approaching 1mm2

microTsunamis (µTs) for rapid, high-throughput screening of exogenous molecules that affect cellular mechanotransduction. A single pulsed laser-microbeam generates a microcavitation bubble. The rapidly expanding bubble displaces surrounding fluid to expose adherent cells to a µT, a transient microscale burst of hydrodynamic shear stress, which mechanically stimulates cells over areas approaching 1 mm2. The µT is integrated into an automated fluorescence microscope and fluorescent markers of cell signaling (illustrated with red shading) can be quantified in response to the transient shear stresses.

IMPACT
Current assays used for screening of small molecule libraries do not assess the ability of these molecules to modulate cellular responses to mechanical cues.  We postulate the existence of classes of ‘mechano-active’ drugs that can target these pathways—drugs that remain undiscovered because there is no practical method to implement high-throughput screening (HTS). The results of numerous studies support the important role of mechanotransduction in many vital processes, including tissue morphogenesis, stem cell differentiation, vascular regulation and tumor metastasis.  Moreover, there is mounting evidence that disruptive mechanical cues and/or dysregulation of mechanotransduction pathways play important roles in the initiation and/or progression of numerous diseases, including atrial fibrillation, hypertension, osteoporosis, digestive diseases and cancer.