Abstract Body (Do not enter title and authors here): BACKGROUND: Electrical and dynamic stimulation are commonly used to enhance the maturation of engineered cardiac tissue (ECT) derived from induced pluripotent stem cells (iPSCs), reflecting the physiological environment of the heart. Electrical stimulation mimics natural bioelectrical signals, while dynamic stimulation replicates mechanical forces. However, the potential synergistic effects of combining electrical and dynamic stimulation simultaneously on ECT maturation have not been thoroughly investigated.
HYPOTHESIS: We hypothesized that simultaneous electro-dynamic stimulation would enhance the maturation and function of the ECT more effectively than either stimulus alone.
METHODS: ECTs were created by co-culturing human iPSC-derived cardiovascular cells with Collagen I and Matrigel for 2 weeks. This was followed by a comparative analysis of four groups: no stimulation, dynamic stimulation, electrical stimulation (3 volts), and simultaneous electro-dynamic stimulation. For simultaneous stimulation, a specially designed sensor generated electrical pulses timed with dynamic mechanical stimulation. The physical training regimen lasted 2 weeks for all groups. The functionality of the ECTs was assessed using a video-based system to measure contractile capacity, and a flux analyzer to evaluate calcium indicators. Histological assessments examined structural maturation.
RESULTS: During protocol optimization, the 30rpm dynamic culture significantly enhanced the cardiomyocyte (CM) component of the ECTs compared to the 60rpm group, highlighting the importance of dynamic stimulation frequency on tissue development. Simultaneous electro-dynamic stimulation significantly increased the CM component of ECT (control vs simultaneous stimulation: 16.1 ± 5.2 % vs 43.5 ± 12.1 %, P= 0.0009), elevated TNNT2 mRNA expression levels, and enhanced calcium transient capacity. Additionally, ECTs subjected to simultaneous stimulation exhibited a positive force-frequency relationship in contractility and an elevation in peak calcium flux, indicative of advanced tissue maturation. Moreover, simultaneous stimulation promoted vascular network formation within the ECTs, suggesting improved structural organization.
CONCLUSION: Simultaneous electro-dynamic stimulation creates ECTs with superior functional and structural properties compared to electrical or dynamic stimulation alone. Simultaneous stimulation protocols are crucial for developing effective cardiac tissue engineering strategies.