[The impact of low intensity pulsed ultrasound on mouse skull bone osteoblast cultures].
BACKGROUND
Low intensity pulsed ultrasound (LIPUS) is one of the methods used to stimulate bone regeneration. This technique is still not well known or explained. The expression of several proteins (VEGF, IL-8, FGF-β, IL-1 β) or genes (ALP and OP) was increased after being exposed to weak ultrasounds, whereas IL-6 and TNF-α were not affected. The purpose of this study was to verify and understand the mechanisms involved in this stimulation, and more specifically to understand if the stimulation concerned only cellular differentiation factors or if it also affected transcription of stem cells into osteoblasts.


METHODS
Cultures of mouse skull bone osteoblasts were exposed to pulsed ultrasounds of varying intensities during three consecutive days. The effect of this stimulation was assessed by counting cells and determining the number of bone nodules formed. We studied various genes participating in osteoblast proliferation or in the differentiation and transcription of osteoblasts, using reverse transcriptase PCR.


RESULTS
The cellular proliferation of osteoblasts was increased after stimulation by low intensity pulsed ultrasound. The expression of various genes involved in differentiation and transcription of stem cells into osteoblasts was increased, especially after stimulating at 100 mW/cm(2).


CONCLUSIONS
Low intensity pulsed ultrasound allows stimulation of bone proliferation in vitro by stimulating osteoblastic differentiation and transcription.
Groupement hospitalier Nord, université Claude-Bernard Lyon 1, 93, Grande Rue de la Croix-Rousse 69004 Lyon, France. arnaud.gleizal@chu-lyon.fr
A
A
Gleizal
S
S
Ferreira
B
B
Lavandier
B
B
Simon
J-L
JL
Béziat
J-C
JC
Béra
D000469:Alkaline Phosphatase / Q000032:analysis; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000032:analysis; D055415:Bone Morphogenetic Protein 4 / Q000032:analysis; D055419:Bone Morphogenetic Protein 7 / Q000032:analysis; D002113:Calcification, Physiologic / Q000502:physiology; D002452:Cell Count; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D024042:Collagen Type I / Q000032:analysis; D050659:Core Binding Factor Alpha 1 Subunit / Q000032:analysis; D016326:Extracellular Matrix Proteins / Q000032:analysis; D020869:Gene Expression Profiling; D051379:Mice; D010006:Osteoblasts / Q000166:cytology*; D053495:Osteopontin; D018125:Receptors, Transforming Growth Factor beta / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012886:Skull / Q000166:cytology*; D013997:Time Factors; D014158:Transcription, Genetic / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000032:analysis; D014465:Ultrasonics; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis
C525719:Bmp2 protein, mouse; C525810:Bmp4 protein, mouse; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; C513308:Dmp1 protein, mouse; D016326:Extracellular Matrix Proteins; D018125:Receptors, Transforming Growth Factor beta; C493716:Runx2 protein, mouse; C506896:Spp1 protein, mouse; D016212:Transforming Growth Factor beta; D042461:Vascular Endothelial Growth Factor A; C525820:bmp7 protein, mouse; C467480:vascular endothelial growth factor A, mouse; D053495:Osteopontin; D000469:Alkaline Phosphatase