Mandibular Periosteal Cells Exhibit Trpv2-Dependent Mechanosensitivity to Microscale Stiffness Patterns

The clinical need for maxillofacial reconstruction requires a deeper understanding of site-specific skeletal stem cell biology. The periosteum serves as a critical reservoir of adult skeletal stem progenitor cells (SSPCs) that navigate microscale stiffness gradients during bone healing. However, whether periosteal SSPCs from distinct skeletal sites exhibit divergent mechanosensitive responses remains poorly understood. This study compared the phenotypic characteristics and mechanotactic behaviors of mouse periosteal SSPCs (passage 3) from mandible (m-pSSPCs) and long bone (l-pSSPCs). Furthermore, we evaluated cell migration and adhesion using our previously reported flat PDMS substrate with periodic subsurface stiffness patterns (20-µm or 50-µm periods; stiffness differentials of ~0.3 MPa and ~0.5 MPa, respectively). While both cell types exhibited similar basal morphologies, flowcytometry and western blot analysis revealed a significantly higher proportion of osteogenic progenitors in m-pSSPCs compared to l-pSSPCs. Notably, m-pSSPCs displayed scale-dependent directional migration, morphological elongation and alignment exclusively on 50-µm patterns, whereas l-pSSPCs remained unresponsive across all scales. Transcriptomic profiling identified a marked enrichment of calcium-channel genes in m-pSSPCs, with Trpv2 significantly upregulated. Selective Trpv2 silencing abolished the characteristic polarization and alignment of m-pSSPCs on 50-μm stiffness patterns. Our findings demonstrate that m-pSSPCs possess a unique, Trpv2-dependent sensitivity to microscale mechanical cues, revealing site-specific mechanosensing programs in skeletal progenitors. These results highlight the necessity of considering tissue-specific cellular programs when designing “instructive” biomaterials for craniofacial regeneration.