Comparison of the Biomechanical Properties between Healthy and Whole Human and Porcine Stomachs

Abstract

Gastric cancer poses a societal and economic burden, prompting an exploration into the development of materials suitable for gastric reconstruction. However, there is a dearth of studies on the mechanical properties of porcine and human stomachs. Therefore, this study was conducted to elucidate their mechanical properties, focusing on interspecies correlations. Stress relaxation and tensile tests assessed the hyperelastic and viscoelastic characteristics of porcine and human stomachs. The thickness, stress-strain curve, elastic modulus, and stress relaxation were assessed. Porcine stomachs were significantly thicker than human stomachs. The stiffness contrast between porcine and human stomachs was evident. Porcine stomachs demonstrated varying elastic modulus values, with the highest in the longitudinal mucosa layer of the corpus and the lowest in the longitudinal intact layer of the fundus. In human stomachs, the elastic modulus of the longitudinal muscular layer of the antrum was the highest, whereas that of the circumferential muscularis layer of the corpus was the lowest. The degree of stress relaxation was higher in human stomachs than in porcine stomachs. This study comprehensively elucidated the differences between porcine and human stomachs attributable to variations across different regions and tissue layers, providing essential biomechanical support for subsequent studies in this field.

Keywords: biomechanical properties; hyperelastic; stomach tissue; uniaxial tension; viscoelastic.

Figure 1

Anatomy and tissue sample dissection of porcine and human stomachs. (a) An external view of a deflated porcine stomach used to estimate its gross dimensions: longitudinal (L_long) and circumferential (L_circ) lengths. (b) An inside view of a porcine stomach that has been opened along its larger curvature, showing original colors for the optical identification of the different regions. (c) An external view of a deflated human stomach used to estimate its gross dimensions: L_long and L_circ. (d) An inside view of a human stomach that has been opened along its larger curvature.

Figure 2

(a) Diagram of the layers of the porcine stomach wall (antrum) stained with hematoxylin and eosin. (b) Rectangular porcine stomach tissue specimens marked with nine tracking points. (c) View of the specimen mounted in the uniaxial testing machine. (d) General configuration of the setup for the uniaxial test.

Figure 3

Schematic diagram of image strain data analysis. (a) At the beginning of the test. (b) At the end of the test. (c) The analysis diagram of the elastic modulus (E).

Figure 4

Thickness comparison of porcine and human stomach samples across each layer and region. All data are presented and mean ± standard deviation. Statistical differences were observed between pigs and humans across different regions and layers (p < 0.001).

Figure 5

The stomach wall exhibits region-, layer-, and orientation-dependent stress–stretch behavior. Longitudinal and circumferential values are shown by solid curves and dotted lines, respectively. Standard deviations are shown as shaded regions. P, pig; H, human; L, longitudinal; C, circumferential.

Figure 6

Elastic moduli for porcine and human stomachs.

Figure 7

The stomach wall exhibits region-, layer-, and orientation-dependent stress relaxation behavior. The Cauchy stress is normalized. Longitudinal and circumferential values are shown by solid curves and dotted lines, respectively. Standard deviations are shown as shaded regions. P, pig; H, human; L, longitudinal; C, circumferential.