title: Segmental bone regeneration using a load-bearing biodegradable carrier of bone morphogenetic protein-2.
abstract: Segmental defect regeneration has been a clinical challenge. Current tissue-engineering approach using porous biodegradable scaffolds to delivery osteogenic cells and growth factors demonstrated success in facilitating bone regeneration in these cases. However, due to the lack of mechanical property, the porous scaffolds were evaluated in non-load bearing area or were stabilized with stress-shielding devices (bone plate or external fixation). In this paper, we tested a scaffold that does not require a bone plate because it has sufficient biomechanical strength. The tube-shaped scaffolds were manufactured from poly(propylene) fumarate/tricalcium phosphate (PPF/TCP) composites. Dicalcium phosphate dehydrate (DCPD) were used as bone morphogenetic protein-2 (BMP-2) carrier. Twenty-two scaffolds were implanted in 5mm segmental defects in rat femurs stabilized with K-wire for 6 and 15 weeks with and without 10 microg of rhBMP-2. Bridging of the segmental defect was evaluated first radiographically and was confirmed by histology and micro-computer tomography (microCT) imaging. The scaffolds in the BMP group maintained the bone length throughout the duration of the study and allow for bridging. The scaffolds in the control group failed to induce bridging and collapsed at 15 weeks. Peripheral computed tomography (pQCT) showed that BMP-2 does not increase the bone mineral density in the callus. Finally, the scaffold in BMP group was found to restore the mechanical property of the rat femur after 15 weeks. Our results demonstrated that the load-bearing BMP-2 scaffold can maintain bone length and allow successfully regeneration in segmental defects.
authors.affiliation: Department of Biomedical Engineering, Purdue School of Engineering and Technology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA. tgchu@inpui.edu
authors.forename: Tien-Min G
authors.initials: TM
authors.lastname: Chu
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Warden
authors.forename: Charles H
authors.initials: CH
authors.lastname: Turner
authors.forename: Rena L
authors.initials: RL
authors.lastname: Stewart
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001843:Bone Cements; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000502:physiology*; D001842:Bone and Bones / Q000378:metabolism*; D002130:Calcium Phosphates / Q000737:chemistry; D005269:Femur / Q000473:pathology; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans; D012038:Regeneration; D013314:Stress, Mechanical; D023822:Tissue Engineering / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods; D016212:Transforming Growth Factor beta / Q000502:physiology*
chemical_list: D001672:Biocompatible Materials; C525720:Bmp2 protein, rat; D001843:Bone Cements; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D002130:Calcium Phosphates; D016212:Transforming Growth Factor beta; C020243:calcium phosphate; C494366:calcium phosphate, dibasic, dihydrate