A serum-free adipose-conditioned medium delays stem cell senescence and maintains tissue homeostasis via IL-6/STAT3 axis suppression

BACKGROUND: Stem cell exhaustion and cellular senescence(definition) are two telomere(definition) attrition, cellular senescence)." style="text-decoration:underline dotted; text-underline-offset:2px; cursor:help;">hallmarks of aging(definition). Mesenchymal stem cells (MSCs), as key players in tissue regeneration, are particularly vulnerable to senescence, which compromises both their endogenous regenerative capacity and their therapeutic efficacy in cell-based applications. Suppressing MSC senescence is therefore essential for developing effective regenerative and anti-aging strategies. METHODS: We developed a serum-free adipose-conditioned medium (SF-ACM) from in vitro-cultured human adipose explants. Its anti-aging effects were evaluated in oxidative stress-induced and replicative senescence models of human adipose-derived stem cells (ADSCs), assessing proliferation, senescence markers, migration, and trilineage differentiation. Parallel experiments in senescent human dermal fibroblasts (HDFs) examined proliferation, fibrosis, and senescence features. In vivo, male C57BL/6 J mice (4 or 16 months old) with D-galactose-induced and naturally aged mice received intraperitoneal SF-ACM. Aging phenotypes were analyzed in skin, adipose tissue, muscle, kidney, and serum, along with hepatic and renal safety assessments. RESULTS: SF-ACM significantly reduced senescence-associated markers, including p16, p21, p53, and SA-β-gal, enhanced Lamin B1 expression, and improved the proliferation, migration, and differentiation capacities of ADSCs. It also decreased senescence and fibrosis-related markers in HDFs. In aging mice, SF-ACM improved aging-associated phenotypes in skin, adipose tissue, and skeletal muscle. Mechanistically, these effects were associated with suppression of the IL-6/STAT3 signaling pathway. CONCLUSIONS: This study identifies a novel xenogeneic-free, paracrine-rich formulation that delays cellular senescence and preserves tissue homeostasis. These findings support its potential as a safe and effective strategy to suppress cellular aging, restore stem cell function, and ameliorate tissue-level aging, offering translational promise for regenerative medicine and anti-aging interventions.