3D Printed Gene-activated Octacalcium Phosphate Implants for Large Bone Defects Engineering.

Bone regeneration remains a major challenge in orthopedic and maxillofacial surgery, particularly for large defects. Current methods often fail to achieve sufficient tissue repair due to limitations in structural support and biological signaling. Prior research has shown that gene therapy can enhance osteogenesis, but delivery mechanisms remain suboptimal. This gap motivated the exploration of 3D printing as a platform for controlled implant architecture. The integration of gene-activated scaffolds with 3D printing has not been fully explored in large animal models. Researchers have proposed that combining gene delivery with biodegradable scaffolds could improve healing outcomes. However, no prior work had resolved how to optimize both structural and biological properties in a single implant. This study aims to address these limitations by integrating gene therapy with advanced fabrication techniques.

The study aimed to develop a novel approach for bone regeneration using 3D printed implants activated with plasmid DNA encoding VEGFA. The specific problem addressed is the challenge of achieving effective bone repair in large defects. The motivation stems from the need for implants that provide both structural support and biological signaling. The authors sought to design implants with controlled architecture using ceramic constructs. They aimed to evaluate the implants' biodegradation rate and DNA delivery efficacy in vivo. The study also aimed to test the implants in large animal models to assess clinical potential. The focus was on combining gene therapy with 3D printing to improve osteogenesis. The ultimate goal was to demonstrate the feasibility of this approach for treating critical bone defects.

The researchers designed and fabricated gene-activated implants using 3D printing of octacalcium phosphate and plasmid DNA. X-ray diffraction was used to analyze the chemical composition of the samples. Scanning electron microscopy assessed the microstructure of the implants. Fourier transform infrared spectroscopy confirmed the presence of functional groups. Compressive strength tests evaluated mechanical properties. Subcutaneous implantation in rodents was used to study biodegradation and DNA delivery. Segmental tibia and mandibular defects in adult pigs were substituted with the implants. Computerized tomography, SEM, and histology were used to evaluate osteointegration and bone regeneration.

The 3D printed implants demonstrated structural compliance with digital models. X-ray diffraction confirmed the presence of octacalcium phosphate in the samples. SEM images revealed a porous microstructure suitable for cell infiltration. Compressive strength tests showed acceptable mechanical properties for bone substitutes. In vivo tests indicated controlled biodegradation rates of the implants. The plasmid DNA was effectively delivered and expressed in the surrounding tissue. Computerized tomography showed successful osteointegration in the pig models. Histological examination confirmed effective reparative osteogenesis in the implanted areas.

The combination of gene therapy and 3D printed implants showed significant clinical potential for bone regeneration. The implants provided structural support while delivering VEGFA to enhance osteogenesis. The study demonstrated that the implants could be tailored to match digital models accurately. Biodegradation rates were found to be suitable for tissue repair in large defects. The in vivo tests confirmed the efficacy of plasmid DNA delivery and expression. Osteointegration and reparative osteogenesis were observed in the animal models. The results suggest that this approach could be effective for treating critical bone defects. The authors propose that further studies should explore clinical applications in human trials.