Reprogramming bone progenitor identity and potency through control of collagen density and oxygen tension

The biophysical microenvironment of the cell is being increasingly used to control cell signaling and to direct cell function. Herein, engineered 3D tuneable biomimetic scaffolds are used to control the cell microenvironment of Adipose-derived Mesenchymal Stromal Cells (AMSC), which exhibit a collagen density-specific profile for early and late stage bone cell lineage status. Cell potency was enhanced when AMSCs were cultured within low collagen density environments in hypoxic conditions. A transitional culture containing varied collagen densities in hypoxic conditions directed differential cell fate responses. The early skeletal progenitor identity (PDPN⁺CD146^-CD73⁺CD164⁺) was rescued in the cells which migrated into low collagen density gels, with cells continuously exposed to the high collagen density gels displaying a transitioned bone-cartilage-stromal phenotype (PDPN⁺CD146⁺CD73^-CD164^-). This study uncovers the significant contributions of the physical and physiological cell environment and highlights a chemically independent methodology for reprogramming and isolating skeletal progenitor cells from an adipose-derived cell population.