Assessment of myocardial viscoelasticity with Brillouin spectroscopy in myocardial infarction and aortic stenosis models

Abstract

Heart diseases are associated with changes in the biomechanical properties of the myocardial wall. However, there is no modality available to assess myocardial stiffness directly. Brillouin microspectroscopy (mBS) is a consolidated mechanical characterization technique, applied to the study of the viscoelastic and elastic behavior of biological samples and may be a valuable tool for assessing the viscoelastic properties of the cardiac tissue. In this work, viscosity and elasticity were assessed using mBS in heart samples obtained from healthy and unhealthy mice (n = 6 per group). Speckle-tracking echocardiography (STE) was performed to evaluate heart deformation. We found that mBS was able to detect changes in stiffness in the ventricles in healthy myocardium. The right ventricle showed reduced stiffness, in agreement with its increased compliance. mBS measurements correlated strongly with STE data, highlighting the association between displacement and stiffness in myocardial regions. This correlation was lost in pathological conditions studied. The scar region in the infarcted heart presented changes in stiffness when compared to the rest of the heart, and the hypertrophied left ventricle showed increased stiffness following aortic stenosis, compared to the right ventricle. We demonstrate that mBS can be applied to determine myocardial stiffness, that measurements correlate with functional parameters and that they change with disease.

New Mechanical Markers for Tracking the Progression of Myocardial Infarction

“…9,10 It is noteworthy that simple tissue stiffness cannot detect the initial MI-related mechanical changes in infarcted cardiac tissues. 10,11 Due to the viscoelastic nature of soft tissues, a few attempts have been tried to investigate the dynamical behavior of infarcted cardiac tissue, 12,13 revealing the changes at the midand late-stages of MI (2 or more weeks after MI). For example, atomic force microscopy (AFM) has been used to characterize the altered viscoelastic properties of cardiac tissue ECM after 4 weeks of MI 14 and track mechanical changes in cardiovascular diseases.…”

Modeling cardiomyocyte mechanics and autoregulation of contractility by mechano-chemo-transduction feedback

“…The mechanical stress increases when the cell is contracting under higher resistance or after overload induced damage/remodeling, which would be associated with pathological conditions such as hypertension ( Tello et al., 2019 ), pressure-overload ( Jashari et al., 2015 ), and heart failure with reduced ejection fraction (HFrEF) ( Chandar et al., 2010 ). The stress also increases when the cell is in a stiffer environment, which would be associated with fibrosis ( Naser et al., 2021 ; Neff and Bradshaw, 2021 ; Frangogiannis, 2021 ), infarction ( Villalba-Orero et al., 2021 ), and heart failure with preserved ejection fraction (HFpEF) ( Zile et al., 2015 ). Interestingly, the stress increases with the cell’s aspect ratio (length to width ratio).…”

Silk fibroin increases the elasticity of alginate-gelatin hydrogels and regulates cardiac cell contractile function in cardiac bioinks

“…As previously done in 4%Alg-8%Gel hydrogels, the mechanical properties of SF-based hybrid hydrogels were assessed using two complementary technologies: Brillouin spectroscopy and compression/rheology testing using a standard rheometer [24][25][26].…”

“…First, we evaluated the impact of 1% and 2% SF-containing hydrogels on hybrid hydrogel microstructure using scanning electron microscopy (SEM), and then on mechanical properties via classic compression and rheology testing, as well as advanced and non-destructive Brillouin spectroscopy. Brillouin spectroscopy is highly sensitive to changes in microscopic elasticity and viscosity [24][25][26]. Then, we analyzed the printability and durability of bioprinted SFcontaining hydrogels in cell culture medium at 37 • C. Finally, SF-Alg-Gel hydrogels were tested for their use as bioinks to encapsulate CSs (figure 1).…”