Molecular imaging of the embryonic heart: Fables and facts on 3D imaging of gene expression patterns

Abstract

Molecular imaging, which is the three-dimensional (3D) visualization of gene expression patterns, is indispensable for the study of the function of genes in cardiac development. The instrumentation, as well as the development of specific contrast agents for molecular imaging, has shown spectacular advances in the last decade. In this review, the spatial resolutions, contrast agents, and applications of these imaging methods in the field of cardiac embryology are discussed. Apart from 3D reconstructions from histological sections, not many of these methods have been applied in embryological research. This review shows that, for most methods, neither the spatial resolutions nor the specificity and applicability of the contrast agents are adequate for the reliable imaging of specific gene expression at the microscopic resolution required for embryological studies of small organs like the developing heart. Although a 3D reconstruction from sections will always suffer from imperfections, the resulting reconstructions meet the aim of most biological studies, especially since the original microscopic images are linked. With respect to imaging of gene expression, only histological sections and laser scanning microscopy provide the required resolution and specificity at the tissue and cellular level. Episcopic fluorescence image capturing and optical projection tomography are being used for microscopic phenotyping and lineage analysis, and both show potential for detailed molecular imaging. Other methods can be used very efficiently in rapid evaluation of biological experiments and high-throughput screens of large-scale gene expression profiling efforts when high spatial resolution is not required.

Characterisation of the human embryonic and foetal epicardium during heart development

“…1A-H) to observe the gross anatomy and patterning of the heart (Norris et al, 2013;Ruijter et al, 2004). At late stage CS15 (5 weeks post-conception; equivalent to E11.0 in the mouse embryo; n=2; Fig.…”

Cardiovascular Imaging in Mice

“…From an emitted, focused light source and rotated sample, OPT utilizes projection tomography and in situ immunostains to generate a three-dimensional image of a whole embryo’s gene expression patterns. OPT has been utilized for imaging the developing cardiovascular system and particularly the developing vasculature ex vivo (Ruijter et al, 2004; Walls et al, 2008; Anderson et al, 2013). Most OPT has been performed on fixed and optically cleared specimens, but more recently, live OPT imaging has been achieved (Colas and Sharpe, 2009).…”

Visualizing Plant Development and Gene Expression in Three Dimensions Using Optical Projection Tomography

“…Magnetic resonance imaging (MRI) offers live imaging without depth restriction and can resolve down to 20 mm 3 20 mm 3 1.5 mm (Holbrook et al, 2001). Although it is possible to view gene expression patterns by MRI using contrast agents that can indicate reporter expression in living animals (Louie et al, 2000), this process is not well suited for general applications (Ruijter et al, 2004). The x-ray high-resolution computed tomography (HRCT) allows live imaging to a resolution of 13 mm (http://www.…”