title: A threshold of mechanical strain intensity for the direct activation of osteoblast function exists in a murine maxilla loading model.
abstract: The response to the mechanical loading of bone tissue has been extensively investigated; however, precisely how much strain intensity is necessary to promote bone formation remains unclear. Combination studies utilizing histomorphometric and numerical analyses were performed using the established murine maxilla loading model to clarify the threshold of mechanical strain needed to accelerate bone formation activity. For 7 days, 191 kPa loading stimulation for 30 min/day was applied to C57BL/6J mice. Two regions of interest, the AWAY region (away from the loading site) and the NEAR region (near the loading site), were determined. The inflammatory score increased in the NEAR region, but not in the AWAY region. A strain intensity map obtained from [Formula: see text] images was superimposed onto the images of the bone formation inhibitor, sclerostin-positive cell localization. The number of sclerostin-positive cells significantly decreased after mechanical loading of more than [Formula: see text] in the AWAY region, but not in the NEAR region. The mineral apposition rate, which shows the bone formation ability of osteoblasts, was accelerated at the site of surface strain intensity, namely around [Formula: see text], but not at the site of lower surface strain intensity, which was around [Formula: see text] in the AWAY region, thus suggesting the existence of a strain intensity threshold for promoting bone formation. Taken together, our data suggest that a threshold of mechanical strain intensity for the direct activation of osteoblast function and the reduction of sclerostin exists in a murine maxilla loading model in the non-inflammatory region.
authors.affiliation: Department of Masticatory Function Rehabilitation (Removable Partial Prosthodontics), Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
authors.forename: Natsuki
authors.initials: N
authors.lastname: Suzuki
authors.affiliation: Department of Bio-Matrix (Pharmacology), Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan. kazu.hpha@tmd.ac.jp.
authors.forename: Kazuhiro
authors.identifier: 0000-0001-6643-6315
authors.initials: K
authors.lastname: Aoki
authors.affiliation: Institute of Solid Mechanics, Mechatronics and Biomechanics, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Marcián
authors.affiliation: Institute of Solid Mechanics, Mechatronics and Biomechanics, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic.
authors.forename: Libor
authors.initials: L
authors.lastname: Borák
authors.affiliation: Department of Masticatory Function Rehabilitation (Removable Partial Prosthodontics), Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Wakabayashi
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D015519:Bone Density; D002452:Cell Count; D006023:Glycoproteins / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D008437:Maxilla / Q000166:cytology / Q000502:physiology*; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D010006:Osteoblasts / Q000502:physiology*; D010011:Osteocytes / Q000166:cytology; D010012:Osteogenesis; D013314:Stress, Mechanical; D016474:Weight-Bearing
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; C486030:Sost protein, mouse
keywords: Bone formation; Inflammation; Mechanical strain intensity; Murine maxilla; Numerical analyses; Sclerostin