Human Cardiac Fibroblast Number and Activation State Modulate Electromechanical Function of hiPSC-Cardiomyocytes in Engineered Myocardium

Figure 5

Alternans appear in engineered cardiac tissues dependent on pacing frequency and hCF percentage. (a) Raw force trace acquired during field stimulation at 2.5 Hz. Dashed lines indicate the difference in force amplitude between alternating contractions in systolic alternans (top) and diastolic alternans (bottom). (b) Percentage of tissues exhibiting alternans. (c) The onset of alternans was measured as the pacing frequency at which alternans amplitude reached ≥5% of the total force amplitude. (d) Amplitude of alternans was measured during field stimulation of increasing frequency, and the fraction of full-force contractions was calculated. (e) Normalized alternans amplitude was plotted as a function of the normalized full-force contractile amplitude. The linear regression for control tissues is shown (). independent experiments; the number of tissues per measurement is indicated on each bar. C: control; 5%: +5% hCFs; 10%: +10% hCFs; 15: +15% hCFs. and ; data are represented as .