Circulating Small Extracellular Vesicles of Aged Individuals Promote Higher Senescence Marker Expression and Lower Antioxidant Levels in Hematopoietic Stem Cells Publisher



Afrisham R ; Ahmadvand M ; Sadeghnejadi S ; Kashanikhatib Z ; Kaviani S ; Farrokhi V ; Helali M ; Alizadeh S
Source: Regenerative Engineering and Translational Medicine Published:2026

Abstract

Introduction: Exosomes/small extracellular vesicles (sEVs) can influence various tissues and cells, and hematopoietic stem cells (HSCs) undergo changes with aging. The present investigation aimed to compare the effects of circulating sEVs derived from old and young subjects on senescence marker expression [reactive oxygen species (ROS), p21 and p53] and antioxidant levels [total antioxidant capacity (TAC), and glutathione (GSH)] in umbilical cord blood-derived hematopoietic stem cells (HSCs) for the first time. Methods: Exosomes/sEVs were obtained from four old (O-Exo) and four young (Y-Exo) men and characterized for CD63 expression, zeta potential, size and morphology. The cells were treated with pooled sEVs (5 and 10 µg/mL), and cell viability (using MTT assay), p53 and p21 gene expression (by qRT-PCR), TAC, GSH (kit-based), and ROS (using flow cytometry) were assessed. P53 protein levels were analyzed by Western blot method. Results: HSCs treated with elderly-derived sEVs (5 µg/mL [O5-Exo] and 10 µg/mL [O10-Exo]) exhibited significantly elevated P53 (P = 0.022) and P21 (P = 0.002) mRNA expression compared to the control group. Among all treatment groups, the O10-Exo group demonstrated the most significant upregulation of P53 protein expression (P < 0.05). Compared to the control, ROS levels were significantly increased in HSCs treated with 5 µg/mL (P = 0.022) and 10 µg/mL (P = 0.002) elderly sEVs. Both O5-Exo and O10-Exo treatments significantly decreased GSH and TAC levels in HSCs relative to controls (P < 0.005). Conclusion: Our data demonstrated that sEVs from aged donors significantly upregulated senescence markers (P53, P21) and oxidative stress (ROS) while depleting antioxidant defenses (TAC, GSH) in HSCs compared to young-derived exosomes. © The Author(s), under exclusive licence to The Regenerative Engineering Society 2026.