Dynamic Compression Reveals Donor-Age-Associated Inflammaging in Human Mesenchymal Stromal Cell Spheroids

Mechanical cues play a critical role in musculoskeletal homeostasis and disease pathophysiology, where excessive loading induces tissue damage and promotes inflammation. Aging further exacerbates this process, particularly in age-related diseases, such as osteoarthritis (OA). Although both hyper-mechanical loading and aging are known to contribute to chronic inflammation in OA and other age-related diseases, their combined effects remain poorly modeled in vitro. Here, we developed a dynamic 3D culture platform integrating gelatin hydrogels, human bone marrow-derived mesenchymal stromal cell (MSC) spheroids, and a compressive bioreactor to recapitulate joint-like mechanical environments. Gelatin hydrogel-encapsulated MSC spheroids maintained mechanical stability under repeated loading (10-20 kPa) while preserving cell viability and spreading. Aged MSC spheroids exhibited metabolic reprogramming toward glycolysis, elevated secretion of pro-inflammatory cytokines (IL-6 and IL-8), and increased PIEZO1 expression. Compressive loading further amplified inflammatory signaling and promoted M1-like macrophage polarization, particularly in aged donor-derived MSCs, modeling key features of inflammaging. Dexamethasone suppressed inflammatory cytokine secretion and promoted M2-like macrophage polarization, whereas tocilizumab modulated immune responses without reducing cytokine production. This platform establishes a donor-specific, mechanobiological model of inflammaging for precision therapeutic screening in osteoarthritis and related diseases.