Introduction: 3D printing is an effective technology to fabricate 3D scaffold due to the ability to directly print porous scaffolds with designed shape and interconnected porosity. So it is becoming popular in biomedical field, and damaged tissues could be fixed with a new technique that involves 3D printing and living cells or growth factors. A biocompatible and biodegradable 3 dimensional (3D) porous scaffold is an integral part of bone tissue engineering. It provides mechanical support and a template for cell attachment and stimulates bone tissue formation in vivo. In this study, we fabricated 3D scaffold consisting of polycaprolactone (PCL)/β-tricalcium phosphate (TCP) or PCL/hydroxyapatite (HA), and then compared their bone regeneration efficacy.
Materials and Methods: PCL/TCP or PCL/HA (in 8:2 weight ratio) 3D scaffolds were fabricated using a extrusion-based 3D printing system. The dimensions of scaffolds were 4 mm of diameter and 20 mm of height. The strut size and pore size of scaffold were 300 μm, and 400 μm, respectively. Hydroxyapatite (HA) nano-powder from porcine cancellous bone was produced using Ultra-high nano-disperse. To produce collagen coated PCL/HA, we extracted pepsin-solubilized type I collagen from porcine skin and crosslinked using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) with N-hydroxysuccinimide (NHS). MG63 cells were seeded and cultured on 3D scaffolds, and then cell viability on scaffolds was evaluated by CCK assay. Rabbit long bone defect model was used to evaluate in vivo bone forming capacity of 3D scaffolds. In brief, 20-mm-long 3D scaffolds were implanted in the radial defect, and then plane radiography, microcomputed tomography, and histological analyses were conducted at 8 weeks after surgery.
Results and Discussion: The result of CCK assay showed that the amount of cells on the scaffold were increased with time. The collagen coated PCL/HA scaffold showed the highest cell viability, and PCL/HA and PCL/TCP scaffolds followed. In the rabbit long bone defect model, microcomputed tomography analysis confirmed that the enhanced new bone formation along the 3D scaffold. PCL/HA scaffold showed higher bone formation compared to PCL/TCP scaffold, moreover, collagen coated PCL/HA (Col-PCL/HA) scaffold has the best bone forming capacity at 8 weeks after implantation.
Conclusions: In the present study, we successfully produced HA nano-powder from porcine cancellous bone for 3D printing system, and fabricated 3D porous scaffolds for bone tissue engineering. In addition, we could extract the pure type I collagen from porcine skin. The high cell viability and in vivo bone-forming capacity of PCL/HA and Col-PCL/HA scaffolds suggest the availability of porcine derived hydroxyapatite and collagen for bone regeneration.
This research was supported by a grant of the Commercializations Promotion Agency for R&D Outcomes (COMPA) funded by the Ministry of Science, ICT and Future Planning(MISP), and a grant from the Next-Generation BioGreen 21 Program (No. : PJ01135201), Rural Development Administration, Republic of Korea.
References:
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