Towards non-invasive characterisation of coronary stent re-endothelialisation – An in-vitro, electrical impedance study

Abstract

The permanent implantation of a stent has become the most common method for ameliorating coronary artery narrowing arising from atherosclerosis. Following the procedure, optimal arterial wall healing is characterised by the complete regrowth of an Endothelial Cell monolayer over the exposed stent surface and surrounding tissue, thereby reducing the risk of thrombosis. However, excessive proliferation of Smooth Muscle Cells, within the artery wall can lead to unwanted renarrowing of the vessel lumen. Current imaging techniques are unable to adequately identify re-endothelialisation, and it has previously been reported that the stent itself could be used as an electrode in combination with electrical impedance spectroscopic techniques to monitor the post-stenting recovery phase. The utility of such a device will be determined by its ability to characterise between vascular cell types. Here we present in-vitro impedance spectroscopy measurements of pulmonary artery porcine Endothelial Cells, Human Umbilical Vein Endothelial Cells and coronary artery porcine Smooth Muscle Cells grown to confluence over platinum black electrodes in clinically relevant populations. These measurements were obtained, using a bespoke impedance spectroscopy system that autonomously performed impedance sweeps in the 1kHz to 100kHz frequency range. Analysis of the reactance component of impedance revealed distinct frequency dependent profiles for each cell type with post confluence reactance declines in Endothelial Cell populations that have not been previously reported. Such profiles provide a means of non-invasively characterising between the cell types and give an indication that impedance spectroscopic techniques may enable the non-invasive characterisation of the arterial response to stent placement.

Impedance testing of porous Si3N4 scaffolds for skeletal implant applications

“…Previous work reported in the literature with other cell types (e.g. smooth muscle cells) has shown similar changes in impedance which can be monitored to infer cell behaviour under culture conditions [17] and supports our findings. Table 1 shows the p values from a 2-sample t test performed on the normalized impedance magnitude data taken after 36 h. As expected from observation of the graphs, the p value at high frequencies is high.…”

Predicting Cardiovascular Stent Complications Using Self‐Reporting Biosensors for Noninvasive Detection of Disease

“…Holland et al also investigated EIS for ISR, they used large working electrodes with an oversized counter electrode to evaluate SMCs and ECs in vitro that however these were not suitable for in vivo applications nor had an implant or data telemetry device been developed. [31] Like our work they identified that the impedance of the two cell types differed, hypothesizing that like other researchers the formation of cells tight junctions, cells morphology, and strength of adhesion played key roles in the detection. [21,32] In our work the changes in impedance are hypothesized to be due to the morphological changes of the cells and how those cells spread across the sensor surface.…”

Evaluation of Implanted Stent Occlusion Status Based on Neointimal Tissue Bioimpedance Simulations

“…There exist methods to monitor cell cultures in vivo based on their BI [17][18][19][20]. In [17], a cell-culture was transformed into a "biological oscillator" whose characteristic parameters (i.e., frequency, amplitude, phase, etc.)…”

“…Relevant parameters are extracted from the frequency and amplitude of the oscillations. In [20], primary cells were also cultured and characterized while conforming to the endothelium tissue.…”