A carbon nanotubes based in situ multifunctional power assist system for restoring failed heart function

Figures

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  Fig. 1. Schematic illustration demonstrating the CNTs based multifunctional power assist system (MPS). a Schematic illustration of a normal heart and application of the MPS for a dilated and failed heart. b Microstructure of electric driven multifunctional power assist device. c Schematic indicating SA-CNTs guide the migration of epicardial cells. d Representative images showing MPS in diastolic (left) and systolic state (right). Scale bars, 1 cm. RD-CNT, randomly dispersed carbon-nanotube film; SA-CNTs, superaligned carbon-nanotube sheets. Electrolyte, polyvinyl alcohol (PVA) gel filled with sulfuric acid; Sealing, poly (dimethylsiloxane) (PDMS).

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  Fig. 2. SA-CNTs facilitate epicardial cells outgrowth from embryonic mouse hearts and guide the migration direction of outgrowing epicardial cells. a-f Representative phase contrast light microscopy images of epicardial outgrowth at Day3 indicating peripheral cells on Coverglass resulted in a formation of “Dam” (indicated with white arrow) which hinders the central cells from moving forward until the cells break through the dam (a-c), whereas this phenomenon rarely observed in outgrowing cells on SA-CNTs (d-f). b, c The enlarged image of a selected zone in (a); (e, f) The enlarged image of a selected zone in (d). g Typical image (stitched from two fields of one heart explant) after 4 day of culture showing that epicardial cells on SA-CNTs tend to migrate along the CNT-aligned direction. The maximum transverse and longitudinal migration distance of cells were measured as La and Lb using ImageJ and shown as La/Lb ratio in (h). h Migration pattern indicated using La/Lb ratio (divide La by Lb) showing that epicardial cells on SA-CNTs have its own unique migration manner due to the superaligned structure of SA-CNTs. n = 7 for control sample and n = 13 for SA-CNTs from 5 independent…

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  Fig. 3. SA-CNTs promote EMT in outgrowing epicardial cells. a Representative confocal images indicating that SA-CNTs (mid) and SA-CNTs plus external electrical stimulation (E-SA-CNTs, right) increased the expression of EMT marker α-SMA (red) compared with control (left) after 6 day of culture by immunofluorescent staining of the central cells of the epicardial outgrowth. b mRNA expression of EMT marker α-SMA, Vimentin, sm-MHC and EMT inducer TGF-β1 after 6 day of culture in SA-CNTs and E-SA-CNTs groups. n = 6 for each group from 4 independent experiments. Tests for trends (p for trend) was calculated with Logistic regression. c Representative confocal images indicating that epicardial cells grown out from heart explant placed on SA-CNTs at 6 day of culture exhibited an enhanced migration indicated by greater separation of nuclei and increased presence of lamellipodia. d Quantitation of cell separation (indicated by nuclei distance) of epicardial cells grown out from heart explant on control and SA-CNTs after 6 day of culture. n = 5 for control sample and n = 5 for SA-CNTs from 5 independent experiments. *p < 0.05

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  Fig. 4. Mechanism and performance of the power assist unit. a Electrochemical actuation mechanism of the power assist unit. b Typical CV curves of one actuator petal at different scan rates. c, d Representative cyclic performance of an actuator petal with voltage window of (c) ± 2.5 V and (d) ± 2.0 V at the scan rate of 5 V s− 1, respectively. e Illustration of the systole and diastole of a failed heart post-infarction. Dotted line represents the systolic state and demonstrates the infarcted area with dyskinesis and bulging. The arrow indicates the direction of myocardial movement during contraction. f Stress contribution map of the power assist unit conducted by computer simulation. g Contraction performance of the power assist unit under increased voltage change frequency: 5, 10, 15, 20 and 25 V s− 1, corresponding to a heart systolic-diastolic behavior of 30, 60, 90, 120 and 150 bpm

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  Fig. 5. Clinical applications of the MPS. a Image showing an MPS device attached on the surface of a Tyrode’s solution perfused rabbit heart, covering the apical portion of the heart. Scale bar, 1 cm. b Images indicating that the MPS device dilate (diastole) and contract (systole) along with the beating heart. Scale bars, 1 cm. c ECG tracing demonstrating that the MPS device offers a pacing function owe to excellent attachment. d MPS appearance shown before implantation (left), and macroscopic view of explanted MPS after 4 weeks of subcutaneous implantation (right). e Hematoxylin/eosin staining of tissue section and space (*) left by MPS implant (MPS implant was washed way during staining), after 4 weeks of subcutaneous implantation. Scale bar: 500 μm (left), 50 μm (right). f Schematic illustration demonstrating the potential clinical applications of the electrical driven MPS in dynamic organs with failed function, such as heart, stomach and urinary bladder. Scale bars, 1 cm