Capturing structure and function in an embryonic heart with biophotonic tools

Abstract

Disturbed cardiac function at an early stage of development has been shown to correlate with cellular/molecular, structural as well as functional cardiac anomalies at later stages culminating in the congenital heart defects (CHDs) that present at birth. While our knowledge of cellular and molecular steps in cardiac development is growing rapidly, our understanding of the role of cardiovascular function in the embryo is still in an early phase. One reason for the scanty information in this area is that the tools to study early cardiac function are limited. Recently developed and adapted biophotonic tools may overcome some of the challenges of studying the tiny fragile beating heart. In this chapter, we describe and discuss our experience in developing and implementing biophotonic tools to study the role of function in heart development with emphasis on optical coherence tomography (OCT). OCT can be used for detailed structural and functional studies of the tubular and looping embryo heart under physiological conditions. The same heart can be rapidly and quantitatively phenotyped at early and again at later stages using OCT. When combined with other tools such as optical mapping (OM) and optical pacing (OP), OCT has the potential to reveal in spatial and temporal detail the biophysical changes that can impact mechanotransduction pathways. This information may provide better explanations for the etiology of the CHDs when interwoven with our understanding of morphogenesis and the molecular pathways that have been described to be involved. Future directions for advances in the creation and use of biophotonic tools are discussed.

Optical Coherence Tomography for Brain Imaging and Developmental Biology

“…Cardiac defects in avian embryos caused by ethanol exposure at the gastrulation stage were studied with OCT. These defects included muscular ventricular septal defects, missing or misaligned great vessels, double outlet right ventricle, to hypoplastic or abnormally rotated ventricles [143, 144]. …”

Dynamic imaging and quantitative analysis of cranial neural tube closure in the mouse embryo using optical coherence tomography

“…Utilizing low-coherence light in the near-infrared region, OCT features a microscale spatial resolution with an imaging depth at millimeter level in scattering tissues [24], bridging the gap of imaging scales between the confocal and acoustic imaging techniques. This unique spatial imaging scale of OCT has enabled applications ranging from biomedical research [25][26][27] to clinical diagnosis and monitoring [28][29][30]. Embryology is a major research area where OCT shows great promise as a high-resolution unlabeled imaging tool [31][32][33].…”

Four‐dimensional live imaging of hemodynamics in mammalian embryonic heart with Doppler optical coherence tomography

“…Optical coherence tomography (OCT) is an emerging 3D embryonic imaging method with micro‐scale spatial resolution and several millimetres penetration depth . Doppler OCT, based on the optical phase from OCT complex signals, provides the capability of quantitatively mapping the velocities of moving scatters (such as blood cells) inside tissue .…”