A method to quantify mechanobiologic forces during zebrafish cardiac development using 4-D light sheet imaging and computational modeling

Abstract

Blood flow and mechanical forces in the ventricle are implicated in cardiac development and trabeculation. However, the mechanisms of mechanotransduction remain elusive. This is due in part to the challenges associated with accurately quantifying mechanical forces in the developing heart. We present a novel computational framework to simulate cardiac hemodynamics in developing zebrafish embryos by coupling 4-D light sheet imaging with a stabilized finite element flow solver, and extract time-dependent mechanical stimuli data. We employ deformable image registration methods to segment the motion of the ventricle from high resolution 4-D light sheet image data. This results in a robust and efficient workflow, as segmentation need only be performed at one cardiac phase, while wall position in the other cardiac phases is found by image registration. Ventricular hemodynamics are then quantified by numerically solving the Navier-Stokes equations in the moving wall domain with our validated flow solver. We demonstrate the applicability of the workflow in wild type zebrafish and three treated fish types that disrupt trabeculation: (a) chemical treatment using AG1478, an ErbB2 signaling inhibitor that inhibits proliferation and differentiation of cardiac trabeculation; (b) injection of gata1a morpholino oligomer (gata1aMO) suppressing hematopoiesis and resulting in attenuated trabeculation; (c) weak-atriumm58 mutant (wea) with inhibited atrial contraction leading to a highly undeveloped ventricle and poor cardiac function. Our simulations reveal elevated wall shear stress (WSS) in wild type and AG1478 compared to gata1aMO and wea. High oscillatory shear index (OSI) in the grooves between trabeculae, compared to lower values on the ridges, in the wild type suggest oscillatory forces as a possible regulatory mechanism of cardiac trabeculation development. The framework has broad applicability for future cardiac developmental studies focused on quantitatively investigating the role of hemodynamic forces and mechanotransduction during morphogenesis.

Spatial and temporal variations in hemodynamic forces initiate cardiac trabeculation

“…By integrating light-sheet imaging with the synchronization algorithm for the cardiac cycles (7), followed by segmentation to extract the changes in 3D ventricular morphology, we recapitulated the time-dependent changes in geometrical fluid domains in response to ErbB2 inhibition, gata1a MO, and wea mutation (7,(33)(34)(35). Registration was performed on the 4D image data using B-spline-based deformable registration methods (36), and the computed deformation field was used to morph the segmented ventricular surface to extract the period of ventricular contraction (22). We quantified the dynamic changes in ventricular volume in response to (a) AG1478 treatment to inhibit ErbB2 (n = 3), (b) gata1a MO injection to reduce viscosity (n = 3) (7, 21), and (c) the wea mutants to arrest atria contraction (n = 3) ( Figure 10A) (5,7).…”

“…Genetic manipulations to reduce endocardial WSS attenuated trabeculation and Notch activity (5,7,21,22). Furthermore, our in silico simulation predicted that ventricular trabeculation promotes kinetic energy (KE) dissipation, whereas the nontrabeculated ventricle lacks KE dissipation, resulting in ventricular remodeling and contractile dysfunction.…”

“…The reconstructed 4D zebrafish images were processed to extract the wall motion of a beating zebrafish ventricle. A detailed account of the computational modeling framework from zebrafish images to blood flow simulation and WSS computation was presented by Vedula et al (22). Briefly, 3D images at mid diastole were segmented using 3D level set segmentation in SimVascular (http://www.simvascular.org) to create a triangulated surface of the ventricle.…”

Saak Transform-Based Machine Learning for Light-Sheet Imaging of Cardiac Trabeculation

“…The application of Saak transform to segment 3-D LSFM-acquired images creates an opportunity to investigate chemotherapyinduced cardiac structure and mechanics. Previously, we needed to perform manual or semi-automated segmentation to reconstruct LSFM architectures for computational fluid dynamics [15,16] and interactive virtual reality [17,18]. The addition of edge detection to Saak transform enables the calculation of surface area in relation to the volume of myocardium.…”

“…Light-sheet fluorescence microscopy (LSFM) is instrumental in advancing the field of developmental biology and tissue regeneration [1][2][3][4]. LSFM systems have the capacity to investigate cardiac ultra-structure and function [5][6][7][8][9][10][11][12][13][14], providing the moving Baek, Zhaoqiang Wang, Mehrdad Roustaei, Dengfeng Kuang, C.-C. Jay Kuo †, and Tzung K. Hsiai † boundary conditions for computational fluid dynamics [15,16] and the specific labeling of trabecular network for interactive virtual reality [17,18]. However, efficient and robust structural segmentation of cardiac trabeculation remains a post-imaging challenge [19][20][21][22][23].…”