Decellularized Extracellular Matrix Mitigates the Senescent Phenotype and Restores Osteogenic Potential in Human Mesenchymal Stromal Cells.

Autologous cell-based approaches for bone repair using mesenchymal stromal cells (MSCs) in older patients are limited in part by cellular senescence, resulting in impaired MSC self-renewal and differentiation. Currently, the field lacks a standardized method to induce senescence in human MSCs and characterize them for experimental use, as well as effective strategies to mitigate the harmful effects of the senescence-associated secretory phenotype (SASP). We previously demonstrated that MSC-secreted decellularized extracellular matrix (dECM) enhances the osteogenic potential and survival of MSCs. We hypothesized that senescent MSCs would exhibit improved osteogenic potential and reduced SASP activity when maintained on dECM. We first demonstrated that a senescent phenotype can be reliably induced in human MSCs through ionizing irradiation coupled with a 21-day preconditioning phase in culture, evidenced by increased beta-galactosidase staining and enlarged cell area. We then observed that senescent MSCs on dECM exhibit improved osteogenic potential and reduced SASP compared to cells on tissue culture plastic, evidenced by quantifying markers of osteogenic differentiation and ELISAs for known inflammatory cytokines. These data support the promise of dECM as an instructive biomaterial to enhance the regenerative potential of MSCs from older patients for autologous bone repair.