These findings have important implications for scientific research as well as pharmaceutical drug discovery and product development. Conversely, normal somatic cells that do not express telomerase have a finite replicative capacity and eventually senesce.
Senescent cells can damage surrounding tissues, contributing to age-related pathologies.
For example, senescent skin fibroblasts can contribute to slower healing and wrinkling. Similarly, senescent retinal pigment epithelial cells can contribute to age-related macular degeneration. The two papers announced today provide new in vitro and the first in vivo data demonstrating that telomerase expression in normal cells results in cellular immortality but does not induce cancer-associated physical and biochemical characteristics. Specifically, the Geron researchers report that human skin fibroblasts and retinal pigment epithelial cells transfected with telomerase over a year ago have been continually dividing and can therefore now be considered immortal. Moreover, these same cells retain normal growth control and do not form tumors in vivo, even after twice the normal maximum number of population doublings.