title: The bone regenerative effect of chitosan microsphere-encapsulated growth hormone on bony consolidation in mandibular distraction osteogenesis in a dog model.
abstract: The purpose of this project was to study the effect of chitosan microsphere-encapsulated human growth hormone, which causes sustained release of chitosan and human growth hormone after implantation on early bony consolidation in distraction osteogenesis of a canine model. Forty-eight dogs were used for this study. An external distraction device was applied to the mandibular body after a vertical osteotomy, and the mandibular distraction was started 5 days after the operation at a rate of 1 mm/d up to a 10-mm distraction. The experimental group was divided into a control group (I), hyaluronic acid group (II), chitosan microsphere group (III), and chitosan microsphere-encapsulated human growth hormone group (IV). Normal saline was injected in group I. In group II, a 1-ml volume of hyaluronic acid solution was injected into the distracted area. In the group III, powder of chitosan microspheres and hGH were mixed with a 1-ml volume of hyaluronic acid to make an injectable form, and it was implanted into the distracted area. In group IV, powder of chitosan microsphere-encapsulated hGH was mixed with a 1-ml volume of hyaluronic acid. A total of 1-ml volume of the solution mix was implanted into the distracted area. Five dogs in each group (total of 20 dogs) were killed 3 weeks after completion of distraction. Twenty-eight dogs were killed at 6 weeks. Bone mineral density was 13.1% of the contralateral normal mandible at 3 weeks and 29.6% at 6 weeks in group I, 16.4% at 3 weeks and 40.4% at 6 weeks in group II, 16.6% at 3 weeks and 45.95% at 6 weeks in group III, and 29.6% at 3 weeks and 66.7% at 6 weeks in group IV. The mean three-point failure load was 16.1% in the control group, 34.7% in group II, 41.5% in group III, and 52.1% in group IV compared with the intact contralateral mandible, with statistical significance. In the histological findings, new bone was generated in all groups. In group IV, the formation of active woven bone was observed throughout the distracted area at 6 weeks. The amount of new bone formation in the distracted zone was in the order of group IV, group III, group II, and the control group. In conclusion, these findings suggest that chitosan microsphere-encapsulated hGH seems to be quite effective in early bone consolidation in distraction osteogenesis.
authors.affiliation: Department of Plastic and Reconstructive Surgery, College of Medicine, Kyungpook National University, Daegu, Korea. bccho@knu.ac.kr
authors.forename: Byung Chae
authors.initials: BC
authors.lastname: Cho
authors.forename: Jong Yeop
authors.initials: JY
authors.lastname: Kim
authors.forename: Jong Hyup
authors.initials: JH
authors.lastname: Lee
authors.forename: Ho Yun
authors.initials: HY
authors.lastname: Chung
authors.forename: Jae Woo
authors.initials: JW
authors.lastname: Park
authors.forename: Kyung Ho
authors.initials: KH
authors.lastname: Roh
authors.forename: Go Un
authors.initials: GU
authors.lastname: Kim
authors.forename: Ick Chan
authors.initials: IC
authors.lastname: Kwon
authors.forename: Kwang Ho
authors.initials: KH
authors.lastname: Jang
authors.forename: Dong-Sin
authors.initials: DS
authors.lastname: Lee
authors.forename: Nang Woon
authors.initials: NW
authors.lastname: Park
authors.forename: In San
authors.initials: IS
authors.lastname: Kim
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage*; D015519:Bone Density; D001861:Bone Regeneration / Q000187:drug effects*; D002686:Chitin / Q000008:administration & dosage* / Q000031:analogs & derivatives*; D048271:Chitosan; D003799:Dental Stress Analysis; D004285:Dogs; D016503:Drug Delivery Systems; D019382:Human Growth Hormone / Q000008:administration & dosage*; D006801:Humans; D006820:Hyaluronic Acid / Q000008:administration & dosage; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008334:Mandible / Q000254:growth & development / Q000601:surgery*; D008863:Microspheres; D019647:Oral Surgical Procedures; D019857:Osteogenesis, Distraction; D018583:Pliability
chemical_list: D001672:Biocompatible Materials; D019382:Human Growth Hormone; D002686:Chitin; D007334:Insulin-Like Growth Factor I; D006820:Hyaluronic Acid; D048271:Chitosan