Abstract
We previously reported that the frequency of polyploidy aortic vascular smooth muscle cells (VSMC) serves as a biomarker of aging. Cellular senescence of somatic cells is another marker of aging that is characterized by the inability to undergo cell division. Here, we examined whether polyploidy is associated with the development of cellular senescence
in vivo
. Analysis of aortic tissue preparations from young and old Brown Norway rats showed that expression of senescence markers such as p16
INK4a
and senescence-associated β-galactosidase activity are detected primarily in the old tissues. VSMC from p16
INK4a
knockout and control mice display similar levels of polyploid cells. Intriguingly, senescence markers are expressed in most, but not all, polyploid VSMC. Moreover, the polyploid cells exhibit limited proliferative capacity in comparison to their diploid counterparts. This study is the first to demonstrate
in vivo
that polyploid VSMC adopt a senescent phenotype.