Human-induced pluripotent stem cell-atrial-specific cardiomyocytes and atrial fibrillation

Figure 1 Progression in atrial fibrillation mechanisms over time. A: Local ectopic focus; B: Single circuit re-entry; C: Multiple circuit re-entry. Paroxysmal atrial fibrillation (AF) is mostly underpinned by local triggers, particularly from pulmonary veins. Re-entry substrates (first functional, then structural) prevail as AF becomes more persistent and, finally, permanent.

Figure 2 Reprogramming of human somatic cells, such as fibroblasts, into human induced pluripotent stem cells is compared with the inner cell mass of embryonic stem cells.

Figure 3 Concept of human induced pluripotent stem cells banks, where blood samples are taken from a “super donor”. Cells from the blood samples are reprogrammed into clinical-grade human induced pluripotent stem cells, which can be distributed to recipients for regenerative medicine.

Figure 4 Action potential of cardiac muscle. Red arrow up represents outward current, green arrow down represents inward currents. Action potential has 5 states: 4, resting; 0, upstroke; 1, early repolarization; 2, plateau; 3, final repolarization. APD: Action potential duration; I_CaL: L-type Ca²⁺ current; I_f: Pacemaker current; I_K: Delayed rectification currents; I_K1: Inward rectifier current; I_KACh: Acetylcholine-activated inward-rectifying potassium current; I_Kr: Rapid; I_Ks: Slow; I_Kur: Ultra-rapid; I_Na: Sodium current; I_to: Transient outward current; NCX, Na +/Ca²⁺ exchanger.