title: Implantation study of a novel hydroxyapatite/collagen (HAp/col) composite into weight-bearing sites of dogs.
abstract: A hydroxyapatite/type I collagen (HAp/Col) composite, aligning hydroxyapatite nanocrystals along collagen molecules, has been prepared. The biocompatibility, osteoconductive activity, and efficacy as a carrier of rhBMP-2 of this novel biomaterial implanted in the weight-bearing site have been examined. The HAp/Col implants (15 mm in diameter and 20 mm in length) with a surface cross-linked layer containing rhBMP-2 (0 or 400 microg/ml) were implanted into bone defects of tibiae in three beagle dogs and fixed according to the Ilizarov method. As a control, bone defects of 20 mm in two beagle dogs did not receive implants, and the dogs were allowed to walk using an Ilizarov extraskeletal fixator. The specimens were removed from one dog in each group after 12 weeks. Also, the Ilizarov fixators in the rhBMP-treated dogs were removed after 12 weeks, after which full weight bearing started. The specimens were further taken out after 18 and 24 weeks in the rhBMP-treated and non-rhBMP-treated dogs, and after 24 weeks in the control group. The change of bone mineral density, as well as radiological and histological findings, suggest that the implants are able to induce bone remodeling units and are a superior carrier of rhBMP-2 due to the stimulation of early callus and new bone formation.
authors.affiliation: Department of Orthopaedic Surgery and Biomechanical Engineering, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Itoh
authors.forename: Masanori
authors.initials: M
authors.lastname: Kikuchi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Takakuda
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Nagaoka
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Koyama
authors.forename: Junzo
authors.initials: J
authors.lastname: Tanaka
authors.forename: Kenichi
authors.initials: K
authors.lastname: Shinomiya
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D015519:Bone Density; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D001861:Bone Regeneration / Q000502:physiology; D018786:Bone Substitutes; D003094:Collagen / Q000737:chemistry / Q000378:metabolism; D004285:Dogs; D006801:Humans; D006882:Hydroxyapatites / Q000737:chemistry / Q000378:metabolism; D018889:Ilizarov Technique; D020007:Implants, Experimental; D008422:Materials Testing; D019736:Prostheses and Implants; D011859:Radiography; D013977:Tibia / Q000166:cytology / Q000000981:diagnostic imaging / Q000502:physiology*; D016212:Transforming Growth Factor beta; D016474:Weight-Bearing
chemical_list: C525718:BMP2 protein, human; D001672:Biocompatible Materials; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D018786:Bone Substitutes; D006882:Hydroxyapatites; D016212:Transforming Growth Factor beta; D003094:Collagen