Healing secret lies in blood.Scientists have long puzzled over why old people and animals heal slower than young ones do. Now, researchers report that a pivotal factor behind this phenomenon circulates in blood. Previous work by Thomas Rando and his colleagues at Stanford University Stanford University, at Stanford, Calif.; coeducational; chartered 1885, opened 1891 as Leland Stanford Junior Univ. (still the legal name). The original campus was designed by Frederick Law Olmsted. David Starr Jordan was its first president. showed that both young and old mice have muscle stem cells stem cells, unspecialized human or animal cells that can produce mature specialized body cells and at the same time replicate themselves. Embryonic stem cells are derived from a blastocyst (the blastula typical of placental mammals; see embryo), which is very young that proliferate pro·lif·er·ate v. To grow or multiply by rapidly producing new tissue, parts, cells, or offspring. into new tissue whenever muscle is injured in·jure tr.v. in·jured, in·jur·ing, in·jures 1. To cause physical harm to; hurt. 2. To cause damage to; impair. 3. . In young mice, these cells respond immediately to injury, but in old mice, the cells are sluggish. Rando's team suspected that a chemical signal either triggers stem cells into action in young mice or inhibits the cells from working in old ones. To determine whether such a signal is in blood, Rando's group connected the circulatory systems circulatory system, group of organs that transport blood and the substances it carries to and from all parts of the body. The circulatory system can be considered as composed of two parts: the systemic circulation, which serves the body as a whole except for the of young and old mice. The scientists removed skin along the flanks of young mice, ages 2 to 3 months, and old mice, ages 19 to 26 months. They then sutured su·ture n. 1. a. The process of joining two surfaces or edges together along a line by or as if by sewing. b. The material, such as thread, gut, or wire, that is used in this procedure. c. pairs of the mice together. The mice quickly adjusted to life as partners, cooperatively eating and roaming their cage. Within several weeks, each pair's blood systems merged. After giving each mouse a leg injury, the researchers found that among the young-old pairs, young mice healed more slowly than did young mice that hadn't been joined and old mice showed significantly faster healing rates than old, solo mice did. Mice paired with a partner of similar age responded much as their unpaired counterparts did. Rando says that these results, published in the Feb. 17 Nature, suggest that blood carries a signal that activates or inhibits stem cells. However, it's still unclear whether old mice make a factor that retards healing or whether young mice make one that spurs healing.--C.B. |
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion