The Dual Role and Characteristics of Senescent Cells

Senescent Cells: A Double-Edged Sword
Senescent cells play a pivotal role in the human aging process. As people age, these cells gradually accumulate in tissues, functioning as a double-edged sword. On one hand, senescent cells provide protective effects in younger years, aiding tissue repair and immune surveillance. On the other, their excessive accumulation due to decreased clearance efficiency disrupts tissue homeostasis, leading to chronic inflammation and age-related diseases. Studies have linked the buildup of senescent cells to conditions such as atherosclerosis, pulmonary fibrosis, diabetes, and cancer.

The Formation and Impact of Senescent Cells
The formation of senescent cells is closely tied to the cellular stress response. When cells experience stress from factors like DNA damage or oxidative stress, they cease dividing to prevent damaged cells from becoming cancerous — a protective biological response. However, these non-dividing cells are not dormant; they secrete a cocktail of inflammatory factors, enzymes, and growth molecules collectively termed the senescence-associated secretory phenotype (SASP). While SASP supports wound healing and immune function in youth, its effects turn detrimental with age. The reduced clearance of senescent cells leads to systemic inflammation and organ dysfunction, underlining their…