Nanowires and Electrical Stimulation Synergistically Improve Functions of hiPSC Cardiac Spheroids

Abstract

The advancement of human induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) technology has shown promising potential to provide a patient-specific, regenerative cell therapy strategy to treat cardiovascular disease. Despite the progress, the unspecific, underdeveloped phenotype of hiPSC-CMs has shown arrhythmogenic risk and limited functional improvements after transplantation. To address this, tissue engineering strategies have utilized both exogenous and endogenous stimuli to accelerate the development of hiPSC-CMs. Exogenous electrical stimulation provides a biomimetic pacemaker-like stimuli that has been shown to advance the electrical properties of tissue engineered cardiac constructs. Recently, we demonstrated that the incorporation of electrically conductive silicon nanowires to hiPSC cardiac spheroids led to advanced structural and functional development of hiPSC-CMs by improving the endogenous electrical microenvironment. Here, we reasoned that the enhanced endogenous electrical microenvironment of nanowired hiPSC cardiac spheroids would synergize with exogenous electrical stimulation to further advance the functional development of nanowired hiPSC cardiac spheroids. For the first time, we report that the combination of nanowires and electrical stimulation enhanced cell-cell junction formation, improved development of contractile machinery, and led to a significant decrease in the spontaneous beat rate of hiPSC cardiac spheroids. The advancements made here address critical challenges for the use of hiPSC-CMs in cardiac developmental and translational research and provide an advanced cell delivery vehicle for the next generation of cardiac repair.

Hydrogel Microchambers Integrated with Organic Electrodes for Efficient Electrical Stimulation of Human iPSC‐Derived Cardiomyocytes

“…Furthermore, the biocompatibility makes it possible to arrange multiple electrodes in a densely‐packed manner for cost‐effective mass production of matured hiPSC‐CMs (Figure S2, Supporting Information). In this study, we focused on hiPSC‐CM spheroids since they are well‐characterized 3D cultures as opposed to the conventional 2D cell culture, however, other techniques for enhancement of maturation such as line patterning and mechanical loading can also be utilized in the hydrogel microchambers by altering the design and dimension of the microchambers and electrodes.…”

“…Immaturity of hiPSC‐CMs leads to a significant risk of arrhythmogenicity in transplantation therapy, and improper disease modeling that does not resemble native adult heart in drug screening . Thus, techniques for promoting maturation of cardiomyocytes are necessary such as long term culture, engineered substrate, cell patterning, application of biochemical cues, mechanical loading, and electrical stimulation . Since one of the fundamental properties of hiPSC‐CMs is their electro‐mechanical communication, electrical stimulation would be a promising approach for mimicking native environment and maturing hiPSC‐CMs to the adult level .…”

“…To overcome the above‐mentioned problems, a hydrogel‐based microchamber that is integrated with highly‐capacitive organic electrodes on the top and the bottom is developed ( Figure 1 a). In this study, we used spheroids of hiPSC‐CMs since such three‐dimensional (3D) cell culture resembled biological environments compared to conventional two‐dimensional (2D) cell culture . The hydrogel microchamber that we developed is permeable to gas and molecules.…”

Advanced Bottom‐Up Engineering of Living Architectures

“…By impregnating gold nanowires in alginate scaffolds researchers were able to enhance the electrical interconnectivity of engineered cardiac 3D microtissues and improve cardiomyocytes phenotype, expression of contractile function markers and ability to generate synchronous contractions . More recently, incorporation of silicon nanowires in human induced pluripotent stem‐cell‐derived cardiomyocytes enabled the assembly of electrically conductive cardiac 3D spheroids with enhanced cell–cell junctions, contractile machinery maturation, and decreased spontaneous beat rate, which could be beneficial for reducing arrhythmia post‐transplantation . Also, nanoparticles comprising conducting polymers (e.g., polypyrrole) were employed to trigger biomolecules delivery upon stimulation with weak external electrical fields, that are known to impact cell processes in angiogenesis, cardiomyogenesis, neurogenesis, and osteogenesis and could thus enable on‐demand microtissue maturation along time …”

State-of-Art Functional Biomaterials for Tissue Engineering

“…Nanomaterials such as carbon nanotubes (CNTs) (Martinelli et al, 2012;Patel et al, 2016), gold (Au) nanorods (Fleischer et al, 2014;Navaei et al, 2016Navaei et al, , 2017Shin et al, 2016), graphene oxide (GO) nanoflakes (Shevach et al, 2013;Park et al, 2015a), silicon nanowires (Park et al, 2015b;Tan et al, 2017), and iron oxide (Han et al, 2015;Richards et al, 2016) in conjugation with the extracellular and intercellular microenvironments of transplanted cells are believed to enable regeneration of injured CMs Amezcua et al, 2016;Mehrali et al, 2017). Regenerative properties of CMs can be measured by obtaining electrical conductivity, protein adsorption affinity, intracellular signaling pathways, and magnetic properties.…”