The Role of SERPINE1 in Coordinating Osteogenesis and Angiogenesis of hDPSCs for Bone Regeneration

The repair of critical-sized bone defects remains a significant clinical challenge due to the difficulty in achieving spatio-temporal coordination between osteogenesis and angiogenesis. This study aimed to identify key molecular regulators bridging these processes in human dental pulp stem cells (hDPSCs) and to evaluate the therapeutic efficacy of a bio-inspired delivery system comprising SERPINE1-loaded hydroxyapatite/chitosan microspheres (HA/CS MS) for vascularised bone regeneration.

Temporal transcriptomic profiling of hDPSCs during osteogenic and angiogenic differentiation was employed to screen for candidate dual-regulators. Functional validation was conducted using lentiviral-mediated gain- and loss-of-function assays, as well as exogenous protein treatment. The regenerative potential was further assessed in a rat critical-sized calvarial defect model using SERPINE1-encapsulated HA/CS MS composites.

Transcriptomic analysis identified SERPINE1 as a pivotal gene consistently upregulated during both differentiation lineages. Mechanistically, SERPINE1 overexpression significantly enhanced osteogenic differentiation, evidenced by increased ALP activity, mineralised nodule formation, and upregulated expression of RUNX2, COL-1, and OPN. Simultaneously, it augmented angiogenic potential by elevating VEGFR2 and CD31 expression. Notably, conditioned media from SERPINE1-overexpressing hDPSCs promoted endothelial tube formation, suggesting a paracrine mechanism. Conversely, SERPINE1 knockdown suppressed these osteo-angiogenic activities. In vivo, the HA/CS MS scaffold demonstrated excellent biocompatibility and controlled release properties. At 4 weeks post-implantation, the SERPINE1-DPSCs/MS group exhibited significantly superior bone regeneration compared to controls (blank, MS, and DPSCs/MS), characterised by marked increases in bone volume fraction (BV/TV), trabecular thickness, and CD31⁺ microvessel density as revealed by micro-CT and histological analyses.

This study establishes SERPINE1 as a crucial hub regulator that coordinates osteogenesis and angiogenesis in hDPSCs. The utilisation of the HA/CS MS delivery system effectively harnesses this dual-functionality, promoting robust vascularised bone formation. These findings provide a novel theoretical basis and a promising translational strategy for biomaterial-based bone tissue engineering.