High‐Throughput Contractile Force Screening for Discovery of Novel Bronchodilators

In pathologies of the heart, blood vessels, and airways, and in cancer as well, the ultimate therapeutic target is often modulation of cellular contractile force. For discovering new therapies, drug screening technologies typically use biochemical or structural surrogates for contractile force rather than contractile force itself. Because such approaches are indirect, some hits are false while other potential hits could be missed. To fill this gap, we developed a new high‐throughput method that utilizes cellular contractile force directly as the reporter ‐‐called contractile force screening (CFS)‐‐ and established feasibility of CFS in the context of drug discovery in asthma. During an acute asthma attack, contractile forces generated by airway smooth muscle cells act to constrict the airway and thus obstruct airflow. To dilate constricted airways, asthma patients use bronchodilators to reduce these contractile forces and thus allow the airway to open more fully, but currently available bronchodilator medications often fail to relax that muscle sufficiently, especially in severe asthma. To address this unmet need for more effective bronchodilator medications, we implemented CFS to evaluate 10,000 small molecule compounds selected randomly from the Chembridge DIVERset® library. Acrylamide gels were made in 96‐well plates and fluorescent markers and collagen were coated onto gel surfaces. Upon each gel we cultured primary human airway smooth muscle (HASM) cells to near confluence. Drug effects were quantified as the ‘force response ratio’, namely, the ratio of the contractile forces before and after drug addition. By screening mixtures of 8 compounds simultaneously, we were able to evaluate 2000 compounds per week in quadruplicate. After retesting individual compounds from initially positives, we identified 2 individual compounds that relaxed HASM cells in a dose‐dependent and a non‐toxic manner. The mechanism of action is still under investigation but we found that these compounds work independent of cAMP. CFS provides a convenient, rapid, and inexpensive platform for drug discovery based upon a physiological endpoint, namely, cell contractile force. Furthermore, CFS technology has the potential to become a new high‐content assay for drug discovery in any disease process in which cellular contractile force plays a central role. Support or Funding Information NIH P50HL107171 (CADET phase I), R01EY019696 (Eye BRP), NRF GRN (NRF‐2013S1A2A2035518)