A Novel Multi-Component 3D-Printed Scaffold for Targeted Bone Tuberculosis Therapy,

Abstract

Delivering therapeutic agents for the effective treatment of bone tuberculosis (TB) is significantly challenged by inadequate drug penetration into the infected skeletal tissues and limited regeneration of damaged bone. Traditional systemic drug administration often fails to achieve desired therapeutic concentrations locally, leading to increased risk of drug resistance, treatment failure, and systemic toxicity. The aim of this study was to develop a novel, multi- component 3D-printed scaffold incorporating bedaquiline (BQ)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles for localized, sustained release and simultaneous bone regeneration in the targeted management of bone TB. The BQ-loaded PLGA nanoparticles were synthesized using a solvent evaporation technique and optimized through a Box– Behnken design (BBD), focusing on critical quality attributes (CQAs). The optimized nanoparticles exhibited an average particle size of approximately 180 nm, a polydispersity index of less than 0.2, and an encapsulation efficiency (EE) of 78 ± 3%. In-vitro drug release assays demonstrated controlled and sustained release kinetics, achieving approximately 85% cumulative drug release over 21 days. The multi-component scaffold was fabricated using advanced 3D printing technology, integrating natural, synthetic, bioactive, and metallic biomaterials, specifically polycaprolactone (PCL), sodium alginate (NaAlg), bioactive glass (BG), and titanium (Ti). The scaffold exhibited a porosity of nearly 70% and demonstrated optimal mechanical properties with a compressive strength around 3.5 MPa. Comprehensive physicochemical, morphological, and thermal characterizations were conducted using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM), confirming the scaffold's desirable structural integrity, thermal stability, and morphological properties. Cytotoxicity assessments performed using the MG-63 osteosarcoma cell line indicated high cell viability exceeding 85% after 72 hours, confirming excellent biocompatibility and suitability for bone tissue engineering applications. An in vivo evaluation in a New Zealand White rabbit femoral defect model provided further evidence of therapeutic efficacy, with histomorphometry analyses revealing bone regeneration at defect sites treated with the scaffold, compared to regeneration in untreated control sites after 4 weeks. Additionally, mechanical testing supported these findings, showing significantly enhanced structural integrity and load-bearing capabilities at the treated sites. The results of this comprehensive study demonstrate that the developed 3D- printed scaffold loaded with BQ-encapsulated nanoparticles effectively addresses the limitations associated with conventional systemic bone TB therapies. The scaffold provides sustained localized drug delivery, reduces systemic side effects, and significantly enhances bone tissue regeneration. This innovative platform holds promise for clinical translation, potentially revolutionizing the management and treatment of bone tuberculosis and similar skeletal conditions requiring targeted therapeutic intervention and robust regenerative support.