Measuring Drug Effects on Cardiomyocyte Contractile Function using a Novel High Throughput Device

Kim, Gyu-Tae 1, 2 ; Shafieyan, Yousef 1 ;  Shen, Trong 3 ;  Hinz, Boris 1, 2, 3

1. Laboratory of Tissue Repair and Regeneration, Matrix Dynamics Group, Faculty of Dentistry, University of Toronto; 2. Cardiovascular Science Collaborative Program, University of Toronto; 3. Institute of Biomaterials and Biomedical Engineering, University of Toronto

Background: Cardiovascular side-effects of drugs put patients at risk and are major reasons for drug retraction from the market. Preclinical high throughput screening (HTS) of compounds for their effects on human cardiomyocytes is in desperate need. However, currently available tests are not able to directly assess the ultimate cardiomyocyte function – contraction. We have developed an HTS-capable device to detect visible deformations exerted by contracting cells to rubber culture surfaces (wrinkles). In pilot studies we demonstrated the suitability of the device for cardiomyocyte culture and quantification of contractile function. We now set out to perform benchmark tests with established benchmark drugs and stem cell-derived cardiomyocytes.

Objectives: To evaluate our novel HTS-capable cell contraction test device for its ability to measure changes in cardiomyocyte contractility in response to a panel of benchmark drugs.

Materials & Methods: A unique silicone rubber polymer that wrinkles under cell force exertion was cast onto the bottom of 96-well plates and covalently functionalized with matrix proteins for cardiomyocyte attachment. Commercially available human induced pluripotent stem cell-derived cardiomyocytes were cultured on the substrate for 10d. Cell contraction was then optically analyzed by quantifying visible wrinkling of the substrate surface for up to 4h. Changes of cardiomyocyte contractile parameters: frequency, amplitude, regularity was tested before and after addition of benchmark drugs epinephrine, isoproterenol, lidocaine, and blebbistatin. 

Results: Epinephrine and isoproterenol treatment increased cardiomyocyte contraction frequencies by 2-fold compared to untreated controls. Lidocaine and blebbistatin elicited decrease in beating frequencies to ~80% of control group. Epinephrine increased the force of contraction by 1.15-fold, whereas blebbistatin treatment decreased cardiomyocyte contraction force to ~35% of control. Lidocaine and isoproterenol showed no significant effect on force of contraction in cardiomyocytes. 

Conclusions: All drugs elicited effects on cardiomyocyte contraction that were in accordance with published clinical and animal experimental data. The HTS-capable cell contraction test device is thus suitable to screen for drug effects on cardiomyocyte contractile function.

Significance/Impact: Our device can predict cardiovascular effects in human and thus eliminate unfit drug compounds that would otherwise go through expensive clinical trials and fail.