Realization of a poro-elastic ultrasound replica of pulmonary tissue

Abstract

In this work we describe the fabrication of a biocompatible hydrophilic scaffold composed of cross-linked gelatin that mimics the porous three-dimensional structure of pulmonary tissue as well as its water content and mechanical properties. The lung replica also reproduces the characteristic sonographic signs of pulmonary interstitial syndrome, the B-lines or ultrasound lung comets.

Keywords: B-lines; echographic signals; gelatin; hydrogels; lung replica; mechanical properties; porosity.

Figure 1. Micrographs of gelatin 5% cross-linked with glutaraldehyde: (A) 10 mM, (B) 1 mM, (C) 0.1 mM and (D) lung histology. The scale bar reported is the same for all pictures.

Figure 2. SEM images of (A) lung replica (5% w/v gelatin cross-linked with 1 mM glutaraldehyde and then freeze-dried) and (B) natural tissue: pore dimension and distribution are similar. Scale bar, 20 μm.

Figure 3. Swelling ratio (black lines) vs. porosity (gray lines) behavior in time.

Figure 4. Compressive stress-strain plots of porous structures (GTA 10 mM, 1 mM and 0.1 mM) and adult bovine pulmonary tissue.

Figure 5. Influence of cross-linking degree on elastic modulus (squares) and water absorption (diamonds) properties of cross-linked gelatin. For the sake of comparison, pulmonary tissue has an elastic modulus of 1.4 kPa (experimental data).

Figure 6. B-line reproduction by hydration of gelatin samples using different controlled water volumes. One 10 μL drop (A) and two drops (B) spaced about 1 cm apart.

Figure 7. A controlled volume of dH₂O on the surface of a freeze-dried sample generates a characteristic B-line: deposition of a drop of water (A), ultrasound probe placed over the drop (B) and detection of the B-line (C).