Cycling to Senescence
Few discoveries have rocked the generally staid world of gerontology research quite like the pronouncement of Leonard Hayflick and Paul Moorehead in their 1961 paper, “The Serial Cultivation of Human Diploid Cell Strains.” It had been dogma for nearly fifty years that cells removed from the body would grow virtually forever in vitro. This directed the attention of everyone interested in aging away from the cell itself and toward factors within the body that caused otherwise immortal cells to age and die. But Hayflick and Moorehead showed otherwise. And they provided convincing evidence that the aging of cells in vitro—replicative senescence, as it came to be called— was a reasonably good reflection of cellular aging in vivo.
With the verification of their finding by others (which took a few years, given the entrenched belief in the inherent immortality of isolated cells), the cell became a primary focus of aging researchers everywhere. But the initial rush of enthusiasm was soon tempered by some serious questions. What is the relation of replicative senescence in vitro to aging of the organism? Could the phenomenon of replicative senescence