Silicon Nanowire-Induced Maturation of Cardiomyocytes Derived from Human Induced Pluripotent Stem Cells

Abstract

The current inability to derive mature cardiomyocytes from human pluripotent stem cells has been the limiting step for transitioning this powerful technology into clinical therapies. To address this, scaffold-based tissue engineering approaches have been utilized to mimic heart development in vitro and promote maturation of cardiomyocytes derived from human pluripotent stem cells. While scaffolds can provide 3D microenvironments, current scaffolds lack the matched physical/chemical/biological properties of native extracellular environments. On the other hand, scaffold-free, 3D cardiac spheroids (i.e., spherical-shaped microtissues) prepared by seeding cardiomyocytes into agarose microwells were shown to improve cardiac functions. However, cardiomyocytes within the spheroids could not assemble in a controlled manner and led to compromised, unsynchronized contractions. Here we show, for the first time, that incorporation of a trace amount (i.e., ~0.004% w/v) of electrically conductive silicon nanowires (e-SiNWs) in otherwise scaffold-free cardiac spheroids can form an electrically conductive network, leading to synchronized and significantly enhanced contraction (i.e., >55% increase in average contraction amplitude), resulting in significantly more advanced cellular structural and contractile maturation.

Carbon nanotube-based substrates promote cardiogenesis in brown adipose-derived stem cells via β1-integrin-dependent TGF-β1 signaling pathway

“…Recently, nanocomposite scaffolds composed of conductive nanowires were confirmed to enhance the maturation of CMs derived from stem cells with a significantly improved sarcomere length and Z-line width. 21 Besides the 26,27,35,36 Our data here also convincingly demonstrate that CNTs enhance the maturation of CMs with higher sarcomere length and greater assembly of gap junctions between adjacent CMs derived from BASCs.…”

“…20 Different striation regions of ten cells were calculated using ImageJ software. Z-line width was also assessed using ImageJ software according to a previous study, 21 and ten α-SA+ cells were measured with ten measurements for each cell. TgF-β1 bioassay TGF-β1 levels in BASCs grown on the scaffolds were quantified using a commercially available ELISA kit (TGF-β1 Emax ® ImmunoAssay System; Promega, Madison, WI, USA) according to the protocol provided by the manufacturer.…”

Inspiration from heart development: Biomimetic development of functional human cardiac organoids

“…Previous work using hiPSC-CM spheroids has indicated conditioning approaches and extended culture are required to enhance the contractile properties toward physiological relevance (14, 79). We next explored the effect of cellular and matrix microenvironment as a biomimetic stimulus in the organoids to promote the contractile properties of hiPSC-CM.…”

“…As described in our previous publication (79), the agarose hydrogel molds were prepared using 2% agarose (Sigma Aldrich, St. Louis, MO) and master micro-molds from Microtissues, Inc (Providence, RI) as negative replicates to create non-adhesive agarose hydrogels molds containing 35 microwells with hemispheric bottoms (800 μm diameter, 800 μm deep) to facilitate the formation of spherical microtissues. Molds were soaked in cell/organoid specific media prior to microtissue fabrication.…”

Nanowires and Electrical Stimulation Synergistically Improve Functions of hiPSC Cardiac Spheroids

“…25 Likewise, electrical nanomaterials have provided an endogenous means of improving electrical conductivities of cardiac microtissues. 29–31 We have previously shown that the addition of electrically conductive silicon nanowires (e-SiNWs), a class of biodegradable nanomaterials, 32 into scaffold-free 3D cardiac spheroids creates an electrically conductive microenvironment and leads to advancement in the function and structural development of hiPSC-CMs. 31 …”