title: Effects of low frequency cyclic mechanical stretching on osteoclastogenesis.
abstract: Bone cells are continuously exposed to mechanical deformations originating from movement. Mechanical stimulation at fundamental frequencies associated with most frequent normal locomotion (0.167-10Hz) has been reported to suppress differentiation of osteoclasts. However, the effects of very low frequency (0.01Hz) stimulation (which could be a frequency component of normal movement and also relevant to locomotion of movement-impaired individuals) on osteoclasts are poorly understood. We examined differentiation of osteoclasts from mouse bone marrow precursors and RAW 264.7 monocytes cultured on an extendable silicone surface that was dynamically stretched at 0.01Hz. Three stimulation regimes were applied: (i) continuously during 4 days of differentiation, (ii) non-continuously, 8h/day for 4 days, and (iii) post-differentiation, when stimulation was applied for 24h after osteoclasts were noted. Low frequency mechanical stimulation did not inhibit osteoclastogenesis. Moreover, the expression of osteoclast marker genes was upregulated in mechanically stimulated cells compared to static control. Conditioned medium collected from osteoclast cultures stimulated non-continuously or post-differentiation induced differentiation of osteoclast precursors plated in standard tissue culture plates. Extracellular signal-regulated kinase (ERK) phosphorylation was increased in mechanically-stimulated cultures compared to static control. Thus, low frequency mechanical stimulation has qualitatively different effects on osteoclast formation compared to stimulation associated with the fundamental frequencies of normal movement.
authors.affiliation: Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, Canada H3A 2B2; Shriners Hospital for Children, 1529 Cedar Avenue, Quebec, Montreal, Canada H3G IA6.
authors.forename: Yousef
authors.initials: Y
authors.lastname: Shafieyan
authors.affiliation: Faculty of Dentistry, McGill University, Montreal, Canada; Shriners Hospital for Children, 1529 Cedar Avenue, Quebec, Montreal, Canada H3G IA6.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Tiedemann
authors.affiliation: Faculty of Dentistry, McGill University, Montreal, Canada; Shriners Hospital for Children, 1529 Cedar Avenue, Quebec, Montreal, Canada H3G IA6.
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Komarova
authors.affiliation: Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, Canada H3A 2B2. Electronic address: thomas.quinn@mcgill.ca.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Quinn
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D017077:Culture Media, Conditioned; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D008297:Male; D008807:Mice, Inbred BALB C; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D010812:Physical Stimulation
chemical_list: D017077:Culture Media, Conditioned; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: Gene expression; Low frequency; Mechanical stimulation; Osteoclast; Signaling pathway