title: Hydroxyapatite-coated double network hydrogel directly bondable to the bone: Biological and biomechanical evaluations of the bonding property in an osteochondral defect.
abstract: We have developed a novel hydroxyapatite (HAp)-coated double-network (DN) hydrogel (HAp/DN gel). The purpose of this study was to determine details of the cell and tissue responses around the implanted HAp/DN gel and to determine how quickly and strongly the HAp/DN gel bonds to the bone in a rabbit osteochondral defect model. Immature osteoid tissue was formed in the space between the HAp/DN gel and the bone at 2weeks, and the osteoid tissue was mineralized at 4weeks. The push-out load of the HAp/DN gel averaged 37.54N and 42.15N at 4 and 12weeks, respectively, while the push-out load of the DN gel averaged less than 5N. The bonding area of the HAp/DN gel to the bone was above 80% by 4weeks, and above 90% at 12weeks. This study demonstrated that the HAp/DN gel enhanced osseointegration at an early stage after implantation. The presence of nanoscale structures in addition to osseointegration of HAp promoted osteoblast adhesion onto the surface of the HAp/DN gel. The HAp/DN gel has the potential to improve the implant-tissue interface in next-generation orthopaedic implants such as artificial cartilage.
  
  
  
  Recent studies have reported the development of various hydrogels that are sufficiently tough for application as soft supporting tissues. However, fixation of hydrogels on bone surfaces with appropriate strength is a great challenge. We have developed a novel, tough hydrogel hybridizing hydroxyapatite (HAp/DN gel), which is directly bondable to the bone. The present study demonstrated that the HAp/DN gel enhanced osseointegration in the early stage after implantation. The presence of nanoscale structures in addition to the osseointegration ability of hydroxyapatite promoted osteoblast adhesion onto the surface of the HAp/DN gel. The HAp/DN gel has the potential to improve the implant-tissue interface in next-generation orthopaedic implants such as artificial cartilage.
authors: Department of Sports Medicine, Graduate School of Medicine, Hokkaido University, Kita-15, Nishi-7, Sapporo 060-8638, Japan.
authors: Susumu
authors: S
authors: Wada
authors: Department of Sports Medicine, Graduate School of Medicine, Hokkaido University, Kita-15, Nishi-7, Sapporo 060-8638, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Kita-21, Nishi-11, Sapporo 001-0021, Japan. Electronic address: nobukita@aol.com.
authors: Nobuto
authors: N
authors: Kitamura
authors: Laboratory of Soft and Wet Matter, Department of Advanced Transdisciplinary Sciences, Faculty of Advanced Life Science, Hokkaido University, Kita-10, Nishi-8, Sapporo 060-0810 Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Kita-21, Nishi-11, Sapporo 001-0021, Japan.
authors: Takayuki
authors: T
authors: Nonoyama
authors: Graduate School of Life Science, Hokkaido University, Kita-10, Nishi-8, Sapporo 060-0810 Japan.
authors: Ryuji
authors: R
authors: Kiyama
authors: Laboratory of Soft and Wet Matter, Department of Advanced Transdisciplinary Sciences, Faculty of Advanced Life Science, Hokkaido University, Kita-10, Nishi-8, Sapporo 060-0810 Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Kita-21, Nishi-11, Sapporo 001-0021, Japan.
authors: Takayuki
authors: T
authors: Kurokawa
authors: Laboratory of Soft and Wet Matter, Department of Advanced Transdisciplinary Sciences, Faculty of Advanced Life Science, Hokkaido University, Kita-10, Nishi-8, Sapporo 060-0810 Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Kita-21, Nishi-11, Sapporo 001-0021, Japan.
authors: Jian Ping
authors: JP
authors: Gong
authors: Department of Sports Medicine, Graduate School of Medicine, Hokkaido University, Kita-15, Nishi-7, Sapporo 060-8638, Japan.
authors: Kazunori
authors: K
authors: Yasuda
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000187:drug effects; D001842:Bone and Bones / Q000187:drug effects* / Q000473:pathology*; D002356:Cartilage / Q000187:drug effects / Q000473:pathology*; D017886:Durapatite / Q000737:chemistry* / Q000494:pharmacology*; D005260:Female; D005782:Gels; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000494:pharmacology*; D007150:Immunohistochemistry; D020007:Implants, Experimental; D008422:Materials Testing; D011817:Rabbits; D055114:X-Ray Microtomography
chemical_list: D005782:Gels; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D017886:Durapatite
keywords: Artificial cartilage; Bone bonding; Double-network gel; Hydroxyapatite; Osteoconductivity