During a study of baboons, it was discovered that as the baboons aged, their skin showed an increased presence of old cells. It is well known that, as we age, the cells capability to divide, dwindles. This state is termed as replicative senescence. This novel research is the first of its kind that places a finger on the presence of such replicatively senescent cells, published in an advanced online edition of science.
According to John Sedivy, a professor of Medical Science at Brown University and a senior scientist in this project, whether old cells contribute to body aging is a highly controversial topic, prompting the skeptics to question this finding. Although, the initial evidence clearly rests in the recent finding, more needs to be known about how cells multiply anywhere from 60 to90 times prior to the onset of senescence, known to protect the body against disease. Old cells still do their job though not with as much vigor as the young cells and hence the reason for all those wrinkles, slackened healing, cancer and an infirm immune system. There is proof that these senescent cells are not benign, but not enough evidence that their numbers are present in large numbers in aged animals.
This marked the beginning of a study by Brown's team which involved Baboons from the research preserve aged between 5 and 30 comparable to human age from 15 to 90. Skin samples were extracted from the monkey's forearms. They were further tested by scientists in the sedivy lab for the presence of six bio markers, which mean the onset of cellular aging. The most important indicator for replicative senescence is telomere dysfunction that stops the division of cells. Infact, scientists did the hair splitting task of counting the cells with bio markers. Their finding revealed that the number of senescent cells increased with advancing age, with cells present in 5 yr olds being as less as 4% compared to a high of 20% in 30 yr olds. Of course this is just the tip of the iceberg; further studies are required to probe deep into the subject.
Utz Herbig ,Brown post-doctoral research fellow is the lead author of the article. Mark Ferreira, Brown undergraduate, Laura Condel and Dee Carey from the Southwest Foundation for Biomedical Research have made noteworthy contributions. This work has been funded by the National Institute on Ageing.