Investigating the bone regeneration activity of PVA nanofibers scaffolds loaded with simvastatin/chitosan nanoparticles in an induced bone defect rabbit model.

This study aims at preparing electrospun PVA NFs incorporating simvastatin/chitosan nanoparticles (SIM CS NPs) as a controlled drug eluting scaffold for bone regeneration. Optimization was performed by Design Expert® software through establishing two factor, three level factorial design, where the independent variables were the applied voltage, flow rate and PVA solution/SIM CS NPs ratio. Formulation variables values for the optimized formula were 18KV, 0.5 mL/h, and 3:1 respectively. NFs diameter and mesh pore size were chosen as the dependent variables. The optimized NFs were evaluated morphologically, chemically, and physically. Additionally, in-vitro SIM release from the scaffolds was investigated along 24 days. Optimum NFs possessed 136 nm diameter size and 6.5 nm porosity. Also, they showed sustained SIM release for 24 days to achieve the desired goal in bone regeneration. The optimized NFs were implanted within induced bone defects in rabbits. In-vivo assessments were performed through cone beam computed tomography 3D images, bone density measurements, histological analysis and bone morphogenetic protein 2 (BMP 2) level. The obtained results proved the high potential of the optimized NFs in promoting bone regeneration compared to untreated group, non-medicated NFs group, free SIM group and NFs loaded with SIM group after 6 weeks of implantation.

Formulation of simvastatin chitosan nanoparticles for controlled delivery in bone regeneration: Optimization using Box-Behnken design, stability and in vivo study.

This study aims to formulate and optimize simvastatin loaded chitosan-tripolyphosphate nanoparticles (SIM CS-TPP NPs) using ionic gelation method to provide a local delivery system that controls and sustains the release of simvastatin in the desired dose to promote bone regeneration. Box-Behnken design was adopted for optimization of the formulation variables of the prepared nanoparticles namely, CS percentage, TPP percentage and homogenization time. The optimized formula was selected and characterized by transmission electronic microscopy, in-vitro release, swelling index and storage stability. The ability of the optimum formula to stimulate bone regeneration upon implantation in bone defect generated in rabbits was also evaluated. The optimum SIM CS-TPP NPs had particle size of 106 nm, zeta potential of 43.3 mv, polydispersity index of 0.295 and entrapment efficiency of 98.78% and also showed good storage stability over the first month in addition to controlled and steady release over 2 weeks that effectively delivered simvastatin in a therapeutic dose needed for bone regeneration. Cone beam computed tomography 3D images, bone density measurements and histopathological analysis confirmed the high potential of SIM CS-TPP NPs in promoting bone regeneration in the generated defects compared to both the non-medicated formula and untreated groups after 6 weeks of implantation.