Multiscale three-dimensional surface reconstruction and surface roughness of porcine left anterior descending coronary arteries

Abstract

The aim of this study was to investigate the multiscale surface roughness characteristics of coronary arteries, to aid in the development of novel biomaterials and bioinspired medical devices. Porcine left anterior descending coronary arteries were dissected ex vivo, and specimens were chemically fixed and dehydrated for testing. Surface roughness was calculated from three-dimensional reconstructed surface images obtained by optical, scanning electron and atomic force microscopy, ranging in magnification from 10× to 5500×. Circumferential surface roughness decreased with magnification, and microscopy type was found to influence surface roughness values. Longitudinal surface roughness was not affected by magnification or microscopy types within the parameters of this study. This study found that coronary arteries exhibit multiscale characteristics. It also highlights the importance of ensuring consistent microscopy parameters to provide comparable surface roughness values.

Keywords: atomic force microscopy; coronary arteries; endothelium; multiscale; scanning electron microscopy; surface roughness.

Figure 1.

(a) Defrosted heart pre-dissection, with apex, base and left coronary artery identified. (b) LAD specimens prepared as 20 mm sections, with longitudinal and circumferential axes labelled.

Figure 2.

2D optical images using Alicona Infinite Focus microscope at (a) 10×, (b) 20×, (c) 50× and (d) 100× magnification.

Figure 3.

3D reconstruction of optical images at (a) 10×, (b) 20×, (c) 50×, and (d) 100× magnification. Specimen dimensions along the x and y axes are (a) 1623 × 1623 µm; (b) 811 × 811 µm, (c) 323 × 323 µm, (d) 162 × 162 µm. Minor residue—white arrow.

Figure 4.

3D reconstruction of SEM images at (a) 100× and (b) 1000× magnification. Specimen dimensions in x and y axis are (a) 1700 × 1230 µm and (b) 170 × 123 µm. Minor residue—white arrow.

Figure 5.

2D SEM images at (a) 100×, (b) 1000× and (c) 2000× magnification. Black arrows—charging of specimen.

Figure 6.

2D AFM image. Black arrows—minor residue. White arrow—longitudinal direction.

Figure 7.

3D reconstruction of AFM image.

Figure 8.

Multiscale analysis of circumferential mean surface roughness for optical (solid marker) and SEM (no-fill marker) at various magnifications (10×, 20×, 50×, 100×, 1000× and 2000×). Error bars are standard deviation. Logarithmic relationship shown.

Figure 9.

Logarithm of magnification levels to base 10 for mean data of (a) Ra_C, and (b) Ra_Cβ, where error bars are standard deviation (solid marker = optical, no-fill marker = SEM, grey square = AFM). Logarithmic relationship shown for optical microscopy.

Figure 10.

Logarithm of magnifications levels to base 10 for mean data of Ra_L, where error bars are standard deviation (solid marker = optical, no-fill marker = SEM, grey square = AFM). No trend noted.