Research progress on blood therapy for anti-aging.

<h4>Background</h4>Blood is best known for its critical roles such as oxygen distribution, nutrient transport, hemostasis, and immune surveillance. However, its impact on biological aging remains unknown. Accumulating evidence indicates that interventions targeting the vascular system may decelerate or even reverse the aging process, such as heterochronic parabiosis (HPB), therapeutic plasma exchange (TPE), platelet-rich plasma (PRP) injection, extracellular vesicles (EVs) transfusion, and platelet factor transfusion.<h4>Aim of review</h4>Our aim is to elucidate the precise interactions between blood components and the bodily aging process, in order to facilitate the development of novel blood therapy strategies to combat aging and prolong healthy lifespan.<h4>Key scientific concepts of review</h4>Here we summarize age-related changes in circulating factors and cells of blood system, then introduce five anti-aging therapy methods targeting the blood, as well as their anti-aging effects and the components responsible for the effects. We also discuss the possible anti-aging mechanisms of these blood therapies and summarize the limitations of these therapies and the challenges in translating them to clinical practice. To address these challenges and limitations, we also propose several emerging research trends in blood-based therapies for anti-aging.