Adult Cardiac Stem cell Aging: Reversible Stochastic Phenomenon?
The aging process is the most important risk factor in the development of cardiovascular disease. Its prevalence increases dramatically with age, reaching epidemic proportions. The heart’s structure and function deteriorates as a result of pathologic changes in the cardiac tissue homeostasis in older people. The phenotypes associated with cardiac aging are well studied, but the discovery that cardiac homeostasis is maintained during the lifespan of mammals by regenerative processes linked to endogenous cardiac-stem cell activation has led to a rethinking of the biology and ageing of mammalian myocardium. In terms of cell renewal and turnover, the classical idea of an adult heart as static has been replaced with a dynamic model where cardiac cells die continuously and are replaced by CSC progeny. CSCs, however, are not immortal. Cellular senescence is characterized by an increase in ROS and oxidative stresses, as well as a loss of telomere/telomerase. This occurs due to physiological and pathological changes that occur with age. The old myocardium retains a functionally competent CSC group that appears to be resistant against the senescent state associated with aging. This latter view sees CSC aging as the result of a stochastic, and therefore reversible, cell autonomous process. CSC aging can be a programmed, cell-cycle dependent process that affects the entire or majority of endogenous CSCs. This would imply that CSCs’ regenerative ability is a natural phenomenon and cannot be saved by stimulating growth. Instead, this would accelerate their exhaustion. It is crucial that these two biological perspectives are resolved in order to develop CSC-based interventions for cardiac aging. This will not only improve health span but also extend lifespan by delaying heart disease-related death.
In the past decade, life expectancy worldwide has increased significantly, despite several chronic diseases continuing to increase, aging being their primary risk factor. The aging process is a natural, inevitable degeneration of biological functions. It’s characterized by a progressive decline in organ and tissue homeostasis. Despite significant improvements in diagnosis, treatment and care, most individuals over 65 suffer from a higher risk of developing cardiovascular diseases (CVDs) with a decrease in their quality of life and ability to carry out normal daily activities . The human heart undergoes many changes as it ages, at the structural, molecular and functional levels.