Effect of biomaterial stiffness on cardiac mechanics in a biventricular infarcted rat heart model with microstructural representation of in situ intramyocardial injectate

• Published in: International journal for numerical methods in biomedical engineering Vol. 39; no. 5; pp. e3693 - n/a
• Main Authors: Motchon, Y. D., Sack, Kevin L., Sirry, M. S., Kruger, M., Pauwels, E., Van Loo, D., De Muynck, A., Van Hoorebeke, L., Davies, Neil H., Franz, Thomas
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.05.2023; Wiley Subscription Services, Inc
• Subjects: Animal models; Animals; Applied Research; Biocompatible Materials; biomaterial injection therapy; Biomaterials; Biomedical materials; cardiac mechanics; Computed tomography; Diastole; Dispersion; Finite element method; Heart; Heart Ventricles; Mathematical models; Mechanical properties; Mechanics (physics); Mechanotransduction; Mechanotransduction, Cellular; Modulus of elasticity; Myocardial Infarction; Myocardium; Myocytes, Cardiac; Rats; Representations; Stiffness; Systole; Ventricle; X-Ray Microtomography; biomaterial injection therapy; finite element method; cardiac mechanics; myocardial infarction
• ISSN: 2040-7939; 2040-7947; 2040-7947
• DOI: 10.1002/cnm.3693

Intramyocardial delivery of biomaterials is a promising concept for treating myocardial infarction. The delivered biomaterial provides mechanical support and attenuates wall thinning and elevated wall stress in the infarct region. This study aimed at developing a biventricular finite element model of an infarcted rat heart with a microstructural representation of an in situ biomaterial injectate, and a parametric investigation of the effect of the injectate stiffness on the cardiac mechanics. A three‐dimensional subject‐specific biventricular finite element model of a rat heart with left ventricular infarct and microstructurally dispersed biomaterial delivered 1 week after infarct induction was developed from ex vivo microcomputed tomography data. The volumetric mesh density varied between 303 mm−3 in the myocardium and 3852 mm−3 in the injectate region due to the microstructural intramyocardial dispersion. Parametric simulations were conducted with the injectate's elastic modulus varying from 4.1 to 405,900 kPa, and myocardial and injectate strains were recorded. With increasing injectate stiffness, the end‐diastolic median myocardial fibre and cross‐fibre strain decreased in magnitude from 3.6% to 1.1% and from −6.0% to −2.9%, respectively. At end‐systole, the myocardial fibre and cross‐fibre strain decreased in magnitude from −20.4% to −11.8% and from 6.5% to 4.6%, respectively. In the injectate, the maximum and minimum principal strains decreased in magnitude from 5.4% to 0.001% and from −5.4% to −0.001%, respectively, at end‐diastole and from 38.5% to 0.06% and from −39.0% to −0.06%, respectively, at end‐systole. With the microstructural injectate geometry, the developed subject‐specific cardiac finite element model offers potential for extension to cellular injectates and in silico studies of mechanotransduction and therapeutic signalling in the infarcted heart with an infarct animal model extensively used in preclinical research. A high‐resolution subject‐specific biventricular finite element model was developed from ex vivo micro‐computed tomography data of a rat heart with antero‐apical infarct and an in situ intramyocardial biomaterial injectate delivered 1 week after coronary occlusion. The microstructural in situ details of the biomaterial injectate in an animal model used extensively in infarct research make the finite element model suitable for multi‐scale predictive simulations of mechanotransduction and cardioprotective signalling of cells transplanted into the infarcted heart with the biomaterial.