A coaxial electrospun bilayered membrane with bone morphogenetic Protein 2/gelatin core and γ-polyglutamic acid/β-tricalcium phosphate shell for alveolar bone regeneration

Guided bone regeneration (GBR) is a widely used clinical strategy to separate fast-proliferating epithelium from osteogenic tissue, thereby facilitating alveolar bone defect repair. In this study, a bilayered membrane was engineered by depositing coaxial electrospun Bone Morphogenetic Protein 2 (BMP2)/gelatin core-γ-poly(glutamic acid) (γ-PGA)/β-tricalcium phosphate (β-TCP) shell onto a chitosan membrane (BMP2-PTGC membrane). Mechanical characterization revealed that the chitosan membrane possessed a dense and stable structure, retaining approximately 80% of its mass after 56 days. Meanwhile, the chitosan promoted molecular interactions with the electrospun layer and significantly enhanced the mechanical strength of the bilayered membrane to 4.60 ± 0.043 MPa. Moreover, the coaxial electrospun porous layer of the bilayered membrane provided sustained BMP2 release. In vitro studies demonstrated that the BMP2-PTGC membrane exhibited good biocompatibility and osteoconductivity, resulting in a 2-fold increase in alkaline phosphatase (ALP) activity compared with the tissue culture polystyrene (TCPS) control. In a rat alveolar bone defect model, the BMP2-PTGC membrane enhanced early osteogenic responses, resulting in a 170% increase in osteocalcin expression and a 2.9-fold reduction in CD68+ macrophage accumulation compared with the untreated control. These regenerative outcomes of the BMP2-PTGC bilayered membrane were comparable to those of a commercial PTFE membrane, supporting its potential as an effective biomaterial for guided bone regeneration.