Proteins guide early heart development.Proteins guide early heart development During the first few months of development, a human embryo's single-chambered heart must somehow transform itself into the four-chambered heart that, if all goes well, will serve as a powerful pump throughout life. If embryonic heart development goes awry a·wry adv. 1. In a position that is turned or twisted toward one side; askew. 2. Away from the correct course; amiss. See Synonyms at amiss. , a life-threatening defect -- such as a hole in the heart -- can result. In a quest that may someday lead to treatments for infants with heart defects, scientists are homing in on a set of proteins that may guide this in utero in utero (in u´ter-o) [L.] within the uterus. in u·ter·o adj. In the uterus. in utero adv. development. The embryo's single-cavity heart contains a layer of jelly-like material sandwiched between an outer layer of muscle tissue and an inner tissue layer known as the endocardium endocardium /en·do·car·di·um/ (-kahr´de-um) the endothelial lining membrane of the cavities of the heart and the connective tissue bed on which it lies. en·do·car·di·um n. pl. . Between the fourth and eighth weeks of gestation, certain cells lining the endocardium, called endothelial cells Endothelial cells The cells lining the inner walls of the blood vessels. Mentioned in: Von Willebrand Disease , break away and migrate through the cardiac jelly cardiac jelly n. The gelatinous noncellular material between the endothelial lining and the myocardial layer of the heart in very young embryos, later serving as a substratum for cardiac mesenchyme. , eventually forming tissue pads that divide the heart into four chambers. But what triggers the cellular journey? Roger R. Markwald, a biologist at the Medical College of Wisconsin in Milwaukee, and his colleagues suggested in 1989 that so-called adherons -- packets of proteins carrying a glue-like substance -- adhere to adhere to verb 1. follow, keep, maintain, respect, observe, be true, fulfil, obey, heed, keep to, abide by, be loyal, mind, be constant, be faithful 2. embryonic endothelial cells and somehow cause them to begin their migration. The team reported experiments demonstrating that chick-embryo endothelial cells placed atop a gel layer in a petri dish pe·tri dish n. A shallow circular dish with a loose-fitting cover, used to culture bacteria or other microorganisms. Petri dish a shallow, circular, glass or disposable plastic dish used to grow bacteria on solid media such as agar. broke away from their neighbors and started to travel into the gel when exposed to adherons isolated from the cardiac jelly of embryonic chick hearts. The researchers have now begun to characterize the mysterious adherons. Their unpublished results suggest that cardiac adherons contain at least five key proteins, Markwald told SCIENCE NEWS. The team now hopes to identify each of these proteins and find out how they guide the crucial transformation to a four-chamber heart. Ultimately, says Markwald, such knowledge might enable researchers to develop drugs that spur self-repair in a newborn's defective heart. |
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