A Novel Three Dimensional Platform For Drug Screening:Chamber-Specific Engineered Cardiac Tissue

The advent of human induced pluripotent stem cell(hiPSC)technology and protocols to efficiently differentiate into cardiomyocytes(CM)can provide limitless cells for disease modeling,drug screening and cell therapy.However,the differentiated cells can not be well applied to myocardial repair due to the heterogeneity of their components.Contractile force is the most important and best understood function of CM.The mechanical properties of CM can be analyzed by building the cells into engineered heart tissue(ECT).As a three dimensional platform,ECT also facilitates assessing various drug response.At present,there are a variety of protocols regarding ECT manufacturing,and they are becoming more mature and steady during the last decade.Nevertheless,the problems of high cost and structural and functional immature still exist.Herein,we generated typical atrial and ventricular cardiomyocytes via regulating retinoid acid signaling during hiPSC cardiac differentiation.Based on distinct metabolic characteristics of CM and non-CM,we specifically defined the components of culture medium and obtained highly purified CMs.Through defining cell composition and content,we cost-effectively developed spontaneous beating ECTs with excellent formation and remodeling within only several hours after manufacturing.We also performed structural analyses and evaluated mechanical characteristics of ECTs at baseline.ECTs showed homogeneity in spatial cell distribution,and immunostaining assays reflected the input cell type and proportion.At baseline,the differences between ACM-ECT and VCM-ECT are comparable to atrial and ventricular cardiac tissue form native adult heart.Additionally,we tested the effect of two kinds of chronotropic and inotropic modulators(isoprenaline and nifedipine)and found that ACM-ECT and VCM-ECT exhibited typical responses to them in a concentrationdependent manner.The ECT platform directly recapitulates mechanical properties of native cardiac tissue.Overall,these results demonstrate a high degree of similarity between hiPSC-CM in ECT format and native human heart tissue,indicating that human ECTs are useful for preclinical drug testing and disease modeling.