Functionalized BMP-2-loaded microspheres combined with a PCL biomimetic scaffold for guiding root development in immature permanent teeth: fabrication and in vitro assessment

Objectives Pulp necrosis in immature permanent teeth arrests root development and compromises long-term prognosis. This study aimed to develop a multifunctional scaffold integrating structural biomimicry, mechanical matching, and sustained growth factor release for orderly root regeneration. Materials and methods A poly(ε-caprolactone) (PCL) conical scaffold was fabricated via melt electrowriting (MEW) combined with mechanical winding. Bone morphogenetic protein‑2 (BMP‑2)-loaded microspheres were prepared and physically incorporated into the scaffold. The scaffold surface was modified with collagen. Human dental pulp stem cells (hDPSCs) were cultured on the scaffold to evaluate proliferation, adhesion, and osteogenic differentiation. Results The scaffold exhibited a trilayer “collagen–microsphere–PCL” architecture with mechanical compatibility (elastic modulus: 22.5 MPa; fracture strength: 5.29 MPa; elongation: 441.59%). Microspheres (2.86 ± 0.45 μm) showed a gradient distribution and sustained release (70–75% over 90 days). In vitro, the scaffold promoted hDPSC adhesion and proliferation and significantly enhanced osteogenic differentiation with elevated alkaline phosphatase activity, upregulated the expression of osteogenic-related genes, and increased protein levels. Conclusions The scaffold integrates structural support, controlled growth factor delivery, and a bioactive interface, offering a promising strategy for root development in immature permanent teeth. Clinical relevance By enabling physiological root development, the scaffold addresses a critical unmet need, offering a viable alternative to conventional root canal therapy.