Fibronectin-guided immune-stromal cell crosstalk promotes angiogenesis in pulp-dentin complex regeneration.

Macrophages are multifunctional immune cells that play crucial roles in immune regulation and tissue regeneration by interacting with various cell types. Although macrophage-stromal cell interactions are widely recognized as essential for tissue regeneration and homeostasis, their precise mechanisms in the pulp-dentin complex, a key functional unit for tooth maintenance, remain incompletely understood. In this study, we investigated the interactions between macrophages and dental pulp stromal cells (DPSCs) within a dental pulp microenvironment in response to dental caries infection. As caries progressed, macrophage-DPSC interactions became increasingly prominent. Whole-transcriptome analysis revealed that these interactions are mediated by fibronectin-integrin engagement, which induces a phenotypic shift in macrophages from pro-inflammatory to pro-angiogenic, mediated by the upregulation of angiogenic chemokines. Integrated analysis of a single-cell RNA sequencing dataset from human pulp tissue further confirmed that caries progression enhanced macrophage-driven angiogenic signalling in the endothelial cell population. Moreover, the altered secretome resulting from the macrophage-DPSC co-culture significantly enhanced in vitro endothelial tube formation and survival, indicating a strong angiogenic potential conducive to tissue regeneration. In a preclinical pulp revascularization model, the application of fibronectin during revascularization enhanced neovascularization, root dentin formation, apical maturation and organized pulp-dentin-like tissue formation. Collectively, these findings indicate that fibronectin is a key regulator that reprogrammes the damaged pulp environment into a pro-angiogenic and regenerative niche through coordinated immune-stromal interactions. This study provides a promising direction for the development of extracellular matrix-based therapeutic strategies in regenerative dentistry.