Development of Novel Human Engineered Heart Tissue Models by the Use of Human iPSCs-Derived Cardiomyocytes and Cardiac-specific Extracellular Matrix

Background and Aims: Cardiac tissue engineering using human Induced pluripotent stem cells derived cardiomyocytes (hiPSCs-CMs) offers unique opportunities for cardiac disease modeling, drug testing, and regenerative medicine. We aimed to combine the hiPSCs technology, directed cardiomyocyte differentiation schemes, cardiac-specific extracellular matrix (ECM), and genetically-encoded calcium and voltage fluorescent reporters to establish clinically-relevant engineered human heart tissue models.

Methods and Results: The hiPSCs were coaxed to differentiate into cardiomyocytes using a monolayer-based directed differentiation system. The hiPSCs-CMs were then combined with a unique ECM gel derived from decellularized pig hearts for the creation of engineered heat tissues (EHTs). The EHT was shaped as a ring, and demonstrated spontaneous continuous contractions. Immunostainings and TEM analysis revealed the presence of cardiomyocytes in a more mature stage of development within the ECM-EHT. Calcium properties were examined by the use of GCaMP5, a genetically-encoded fluorescent calcium indicator. Lentiviral transduction was used to express the GCaMP5 transgene in the hiPSCs-CMs prior to creation of the EHTs. To monitor voltage change in the EHT a stable hiPSCs line expressing the genetically-encoded fluorescent voltage indicator ArcLight-A242 was used. This allowed monitoring changes in action-potential and calcium-handling properties in response to several pharmaceutical agents. In EHTs composed of hiPSC-CMs derived from a long QT syndrome patient, the phenotype of the disease was observed by the use of ArcLight. Finally, the contractile properties of the tissue and the effect of various pharmacological interventions were measured by a sensitive force transducers.

Conclusions: By combining hiPSCs-CMs, cardiac-specific ECM, and genetically-encoded fluorescent indicators we were able to establish a clinically-relevant engineered cardiac-tissue model that can undergo high-resolution, large-scale, long-term, serial functional (electrophysiological, E-C coupling, and mechanical) phenotyping. This approach may bring a unique value to the study of inherited disorders, developmental biology, drug development and testing and regenerative medicine.