Senescence in the aging process.

The accumulation of 'senescent' cells has long been proposed to act as an ageing mechanism. These cells display a radically altered transcriptome and degenerative phenotype compared with their growing counterparts. Tremendous progress has been made in recent years both in understanding the molecular mechanisms controlling entry into the senescent state and in the direct demonstration that senescent cells act as causal agents of mammalian ageing. The challenges now are to gain a better understanding of how the senescent cell phenotype varies between different individuals and tissues, discover how senescence predisposes to organismal frailty, and develop mechanisms by which the deleterious effects of senescent cells can be ameliorated

What could advances in the biology of ageing mean for the quality of later life?

The ageing process is often discussed as though it is unique to humans. However, it can be observed throughout the plant and animal kingdoms. In every species in which it occurs, the ageing process has common traits. It is a progressive, intrinsic, cumulative and deleterious process that eventually gives rise to physiological frailty, morbidity and death. Historically, biogerontology had a slow start but the last 10 years have seen exceptional progress in understanding both why and how ageing changes occur. As a result of this new knowledge, interventions that could produce longer, healthier human lives are close to becoming clinical realities. Unfortunately, the speed and scale of these advances is not well understood outside the relatively small community of biological gerontologists. This article reviews some of these advances for a non-specialist audience, speculates on their potential impact and identifies current barriers to future progress.</p