title: In vivo heat-stimulus-triggered osteogenesis.
abstract: Several studies have reported that heat stress stimulates the activity of osteoblastic cells in vitro. However, few have addressed the effects of heat stress on osteogenesis in vivo, nor have the optimal temperatures for bone formation been determined. The aim of the present study was to investigate the effects of hyperthermia treatment on osteogenesis in a rat tibial defect model. Forty-four Sprague Dawley rats were divided into two groups with or without hyperthermia treatment. A 3-mm circular defect in the proximal tibia filled with magnetite cationic liposomes embedded in alginate beads was subjected to hyperthermia treatment (43-46 °C). Radiological assessment at 2 weeks after the treatment showed that significantly stimulated osteogenesis was observed in the hyperthermia group as compared to the control group (p = 0.003). Histomorphometrical analysis at 2 weeks revealed a significant increase of newly formed bone in the hyperthermia group, compared with the control group (p < 0.001). Area of newly formed bone in each hyperthermia group was significantly increased as compared with the control group (43 °C; p = 0.005, 44 °C; p = 0.019, 45 °C; p = 0.003, and 46 °C; p = 0.003, respectively). Alkaline phosphatase was overexpressed at the surfaces of newly formed bone adjacent to magnetite cationic liposome implantation. Our results demonstrate for the first time that heat stimulus accelerates osteogenesis in vivo, and may thus be of interest as a novel and promising tool to induce osteogenesis clinically as well.
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School and School of Medicine , Nagoya , Japan .
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Ikuta
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Urakawa
authors.forename: Eiji
authors.initials: E
authors.lastname: Kozawa
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Hamada
authors.forename: Takehiro
authors.initials: T
authors.lastname: Ota
authors.forename: Ryuji
authors.initials: R
authors.lastname: Kato
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Honda
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishiguro
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nishida
mesh_terms: D000464:Alginates / Q000737:chemistry; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D052203:Ferrosoferric Oxide / Q000008:administration & dosage; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006358:Hot Temperature; D006979:Hyperthermia, Induced; D008081:Liposomes; D008297:Male; D010012:Osteogenesis / Q000528:radiation effects*; D011859:Radiography; D051381:Rats; D017207:Rats, Sprague-Dawley; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D008081:Liposomes; D020723:Glucuronic Acid; D000469:Alkaline Phosphatase; D052203:Ferrosoferric Oxide
keywords: Heat stress; hyperthermia; osteogenesis