Cardiac Failure in the Chick Embryo Resembles Heart Failure in Humans
The chick embryo is used as a model organism, among others, for studies in pathophysiology and developmental biology of the heart. In shell-less culture (SC), it allows direct visualization of the embryonic and cardiovascular development and the physiological effects of cardiac function. Although it is a well-established model, a continuous visual registration of chick embryos over a longer period of development with great detail has not yet been carried out. We present here, for the first time, time-lapse movies of this development with a special emphasis on vasculogenesis over a recorded period of 9 days, beginning at 2 days of incubation. During these first 11 days, the structural formation of the cardiovascular system is accomplished (which takes &9 to 10 days). The movies depict the complex process of extraembryonic vasculogenesis that occurs parallel to the development of the intraembryonic cardiovascular system and is highly dependent on normal cardiac development and function. Although the initial goal of this study was to document the normal embryonic and cardiovascular development in chicks in SC (Figure 1A, Figure 2 [left], and Movie I), we found that some embryos developed cardiac failure and died within a few hours (Figure 1B, Figure 2 [right], and Movies II through IV). It is of great interest that these embryos display a pattern of cardiac failure similar to that found in humans in end-stage heart failure: central pooling, peripheral vasoconstriction, and later stasis and edema. Considering normal and abnormal vasculogenesis/angiogenesis as one of the fundamental phenomena in pathophysiology and pharmacology of cardiovascular and developmental sciences, we think that the SC model of the chick embryo is of interest to researchers in the field of cardiovascular medicine, because ample opportunities exist with this model to further study cardiac function and vascular diseases. The SCs were created after 48 hours of incubation by transferring the embryos at an early heart looping stage to sterilized hexagonal polystyrene weighing boats in a Petri dish with water. In these SCs, the embryos were reincubated and then moved every 60 minutes from the incubator to a special stage for visual registration with a digital camera (for a detailed description of the experimental design, see the legend of Movie I).
This work was supported by a research grant from the Braukmann-Wittenberg Foundation at Hannover Medical School and a research award endowed by HERZKIND eV (Maximilian-Forschungs-Förderpreis 2004) to Dr Yelbuz. We thank Dr M.L. Kirby, Duke University, and Dr J. Männer, University of Göttingen, for critical reading and corrections.
The online-only Data Supplement, which contains 4 movies, can be found at http://circ.ahajournals.org/cgi/content/full/112/24/e352/DC1.