Abstract 4366162: Electrical Stimulation Enhances Contractile Performance of Tissue-Engineered Pulsatile Conduits with hiPSC-Derived Cardiomyocytes

Abstract

Single ventricle congenital heart defects (SVCHDs) are characterized by the presence of only one functional ventricular chamber. The Fontan procedure, a common palliative intervention, reroutes venous blood from the inferior vena cava directly to the pulmonary arteries using a static conduit. However, the absence of contractility results in passive flow, causing venous congestion and poor pulmonary perfusion. We hypothesize that introducing a conduit with pulsatile function could actively pump venous blood into the lungs and reduce stasis. To test this, we first generated engineered heart tissues (EHTs) by seeding human iPSC-derived cardiomyocytes (hiPSC-CMs) onto decellularized porcine heart matrix (Fig. 1A). These cells expressed cardiac troponin T (cTnT), with initially sparse Connexin 43 (Fig. 1B). Subsequently, two layers of EHTs were wrapped around decellularized human umbilical arteries to fabricate the tissue-engineered pulsatile conduit (TEPC), which were then cultured in a bioreactor under continuous electrical stimulation (Fig. 1C-E). Luminal pressure generated by the TEPCs was measured under spontaneous beating and at pacing frequencies of 1, 1.33, 1.66, and 2 Hz. Under spontaneous conditions, the TEPCs generated a luminal pressure of 0.96 mmHg. With electrical pacing, the luminal pressure increased progressively, reaching 1.07 ± 0.07 mmHg at 1 Hz, 1.45 ± 0.32 mmHg at 1.33 Hz, and 1.61 ± 0.25 mmHg at 1.66 Hz. At 2 Hz, the luminal pressure peaked at 1.87 ± 0.33 mmHg, indicating enhanced contractile performance with electrical stimulation (Fig. 1F). In addition, the molecular characteristics of the TEPCs with/without electrical pacing were evaluated. Immunofluorescence analysis demonstrated that paced TEPCs exhibited higher expression levels of cTnT, compared to non-paced controls. Moreover, the expression of Connexin 43 was notably upregulated in electrically stimulated TEPCs, with Connexin 43 predominantly localized at intercellular junctions, indicating enhanced gap junction formation and cellular connectivity. In contrast, TEPCs cultured without electrical pacing showed reduced Connexin 43 expression (Fig. 2). These results demonstrate that electrical stimulation significantly enhances the contractile performance of TEPCs. Our work presents a proof-of-concept strategy for developing a pulsatile conduit as a potential curative therapy for SVCHDs, establishing a critical foundation for future clinical translation.