ABT263, a BCL-2 and BCL-xL inhibitor, effectively clears senescent cells (SCs) in mice, rejuvenating aged hematopoietic stem cells (HSCs) and muscle stem cells (MuSCs). The study shows that ABT263 selectively kills SCs in culture and in vivo, reducing their accumulation after genotoxic stress like total-body irradiation (TBI). This clearance mitigates TBI-induced premature aging of the hematopoietic system and rejuvenates aged HSCs and MuSCs. ABT263 induces apoptosis in SCs, as evidenced by increased caspase-3 activity and reduced expression of anti-apoptotic proteins like BCL-2 and BCL-xL. The drug also reduces the expression of senescence-associated secretory phenotype (SASP) factors, improving the bone marrow microenvironment. In normally aged mice, ABT263 reduces age-related increases in Cdkn2a, Tnfa, and Ccl5 mRNA levels in the lungs, and improves the clonogenicity and engraftment ability of HSCs and MuSCs. The results suggest that ABT263 could be a potential therapeutic agent for radiation injury and aging. However, the drug has toxic side effects like thrombocytopenia and neutropenia, which need to be addressed for its use in anti-aging therapies. The study highlights the role of SCs in aging and provides a new approach for rejuvenating tissue stem cells through senolytic drugs.ABT263, a BCL-2 and BCL-xL inhibitor, effectively clears senescent cells (SCs) in mice, rejuvenating aged hematopoietic stem cells (HSCs) and muscle stem cells (MuSCs). The study shows that ABT263 selectively kills SCs in culture and in vivo, reducing their accumulation after genotoxic stress like total-body irradiation (TBI). This clearance mitigates TBI-induced premature aging of the hematopoietic system and rejuvenates aged HSCs and MuSCs. ABT263 induces apoptosis in SCs, as evidenced by increased caspase-3 activity and reduced expression of anti-apoptotic proteins like BCL-2 and BCL-xL. The drug also reduces the expression of senescence-associated secretory phenotype (SASP) factors, improving the bone marrow microenvironment. In normally aged mice, ABT263 reduces age-related increases in Cdkn2a, Tnfa, and Ccl5 mRNA levels in the lungs, and improves the clonogenicity and engraftment ability of HSCs and MuSCs. The results suggest that ABT263 could be a potential therapeutic agent for radiation injury and aging. However, the drug has toxic side effects like thrombocytopenia and neutropenia, which need to be addressed for its use in anti-aging therapies. The study highlights the role of SCs in aging and provides a new approach for rejuvenating tissue stem cells through senolytic drugs.