Construction and establishment of a new environmental chamber to study real-time cardiac development

Automated Multichamber Time-lapse Videography for Long-term In Vivo Observation of Migrating Cells

AIM

To observe and document the migration of living cells by time-lapse videography, we constructed a low-budget system based on a common inverted microscope.

MATERIALS AND METHODS

Long-term observation of six-well plates is enabled through maintenance of cell culture conditions (5% CO₂ in air at 37°C). Points of interest can be revisited in definable intervals with <1 μm repositioning error. Digital photographs from each programmed time point are paired with environmental data and combined into a record.

RESULTS

We used this new chamber to observe the migration of various cell lines. The design represents a good compromise between low cost and good precision. Detailed analyses verified that the environmental conditions were appropriately maintained, enabling long-term observation of viable cells. The stimulating influence of irradiation with photons (radiotherapy) on cellular motility of glioblastoma cells is presented.

CONCLUSION

This study demonstrates that useful videographic systems can be constructed at low cost.

Investigating developmental cardiovascular biomechanics and the origins of congenital heart defects

Innovative research on the interactions between biomechanical load and cardiovascular (CV) morphogenesis by multiple investigators over the past 3 decades, including the application of bioengineering approaches, has shown that the embryonic heart adapts both structure and function in order to maintain cardiac output to the rapidly growing embryo. Acute adaptive hemodynamic mechanisms in the embryo include the redistribution of blood flow within the heart, dynamic adjustments in heart rate and developed pressure, and beat to beat variations in blood flow and vascular resistance. These biomechanically relevant events occur coincident with adaptive changes in gene expression and trigger adaptive mechanisms that include alterations in myocardial cell growth and death, regional and global changes in myocardial architecture, and alterations in central vascular morphogenesis and remodeling. These adaptive mechanisms allow the embryo to survive these biomechanical stresses (environmental, maternal) and to compensate for developmental errors (genetic). Recent work from numerous laboratories shows that a subset of these adaptive mechanisms is present in every developing multicellular organism with a “heart” equivalent structure. This chapter will provide the reader with an overview of some of the approaches used to quantify embryonic CV functional maturation and performance, provide several illustrations of experimental interventions that explore the role of biomechanics in the regulation of CV morphogenesis including the role of computational modeling, and identify several critical areas for future investigation as available experimental models and methods expand.

A detailed atlas of chick heart development in vivo

Various model organisms such as mouse, xenopus, or zebrafish embryos have been studied in the past to gain insight into the complex processes driving normal and abnormal development of the vertebrate heart. Despite the fact that the chicken embryo has been a favored classic model system used by embryologists and cardiovascular scientists for centuries to illustrate the principles of basic vertebrate embryology and cardiovascular development, so far, no one has provided a thorough documentation of heart development in this model from early visual stages to the stage of a completely formed heart with (a) images and (b) video recordings of beating hearts. However, in vivo documentation of heart development stages is indispensable because the initially tubular embryonic heart not only undergoes dramatic morphological changes, but also intriguing functional changes during cardiogenesis, which, only if they follow and remain within the normal developmental pathway, lead to the establishment of the normal four-chambered heart. In this work we present the first reference catalogue of cardiac development in vivo with (1) 25 plates of high resolution colour images in different views from Hamburger-Hamilton (HH)-stage 12 (day 2, relatively straight heart tube, early myocardial contractions) through HH-stage 35 (day 9, four-chambered heart) in end-diastole and end-systole, including a plate with an overview of all these stages; (2) collection of 82 video recordings of beating hearts in different views corresponding to the stages shown in the plates.

Integration of an optical coherence tomography (OCT) system into an examination incubator to facilitate in vivo imaging of cardiovascular development in higher vertebrate embryos under stable physiological conditions

High-resolution in vivo imaging of higher vertebrate embryos over short or long time periods under constant physiological conditions is a technically challenging task for researchers working on cardiovascular development. In chick embryos, for example, various studies have shown that without appropriate maintenance of temperature, as one of the main environmental factors, the embryonic heart rate drops rapidly and often results in an increase in regurgitant flow. Hemodynamic parameters are critical stimuli for cardiovascular development that, for a correct evaluation of their developmental significance, should be documented under physiological conditions. However, previous studies were mostly carried out outside of an incubator or under suboptimal environmental conditions. Here we present, to the best of our knowledge, the first detailed description of an optical coherence tomography (OCT) system integrated into an examination incubator to facilitate real-time in vivo imaging of cardiovascular development under physiological environmental conditions. We demonstrate the suitability of this OCT examination incubator unit for use in cardiovascular development studies by examples of proof of principle experiments. We, furthermore, point out the need for use of examination incubators for physiological OCT examinations by documenting the effects of room climate (22°C) on the performance of the cardiovascular system of chick embryos (HH-stages 16/17). Upon exposure to room climate, chick embryos showed a fast drop in the heart rate and striking changes in the cardiac contraction behaviour and the blood flow through the vitelline circulation. We have documented these changes for the first time by M-mode OCT and Doppler M-mode OCT.

In vivo imaging of the cyclic changes in cross-sectional shape of the ventricular segment of pulsating embryonic chick hearts at stages 14 to 17: a contribution to the understanding of the ontogenesis of cardiac pumping function

The cardiac cycle-related deformations of tubular embryonic hearts were traditionally described as concentric narrowing and widening of a tube of circular cross-section. Using optical coherence tomography (OCT), we have recently shown that, during the cardiac cycle, only the myocardial tube undergoes concentric narrowing and widening while the endocardial tube undergoes eccentric narrowing and widening, having an elliptic cross-section at end-diastole and a slit-shaped cross-section at end-systole. Due to technical limitations, these analyses were confined to early stages of ventricular development (chick embryos, stages 10-13). Using a modified OCT-system, we now document, for the first time, the cyclic changes in cross-sectional shape of beating embryonic ventricles at stages 14 to 17. We show that during these stages (1) a large area of diminished cardiac jelly appears at the outer curvature of the ventricular region associated with formation of endocardial pouches; (2) the ventricular endocardial lumen acquires a bell-shaped cross-section at end-diastole and becomes compressed like a fireplace bellows during systole; (3) the contracting portions of the embryonic ventricles display stretching along its baso-apical axis at end-systole. The functional significance of our data is discussed with respect to early cardiac pumping function.