Effects of ultrasound on the proliferation and differentiation of cementoblast lineage cells.
BACKGROUND
The purpose of this study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) stimulation on the proliferation and differentiation of cementoblast lineage cells.


METHODS
An immortalized human periodontal ligament cell line (HPL) showing immature cementoblastic differentiation was used. Cultured HPL cells were subjected to LIPUS exposure (frequency = 1 MHz; pulsed 1:4; intensity = 30 mW/cm(2)) or sham exposure for 15 minutes per day. Expression levels of alkaline phosphatase (ALP), type I collagen (Col-I), runt-related gene 2 (Runx2), bone sialoprotein (BSP), osteocalcin (OCN), and osteopontin (OPN) mRNA were analyzed with real-time polymerase chain reaction analysis. Furthermore, ALP activity, collagen synthesis, and protein level of Runx2 were examined after 6 days of LIPUS exposure.


RESULTS
mRNA and protein levels of ALP, Col-I, and Runx2 were significantly increased by LIPUS exposure compared to controls, whereas BSP, OCN, and OPN mRNA expression could not be detected in HPL cells, irrespective of LIPUS exposure.


CONCLUSIONS
LIPUS enhanced ALP activity, collagen synthesis, and Runx2 expression of HPL cells, which provides important insight into the promotion of early cementoblastic differentiation of immature cementoblasts.
Inubushi
T
T
Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
Tanaka
E
E
Rego
E B
EB
Kitagawa
M
M
Kawazoe
A
A
Ohta
A
A
Okada
H
H
Koolstra
J H
JH
Miyauchi
M
M
Takata
T
T
Tanne
K
K
D000469:Alkaline Phosphatase / Q000032:analysis; D015415:Biomarkers / Q000032:analysis; D015153:Blotting, Western; D002454:Cell Differentiation; D002460:Cell Line; D019070:Cell Lineage; D049109:Cell Proliferation; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis; D024042:Collagen Type I / Q000032:analysis; D050659:Core Binding Factor Alpha 1 Subunit / Q000032:analysis; D003739:Dental Cementum / Q000166:cytology*; D006801:Humans; D058574:Integrin-Binding Sialoprotein; D015675:Osteocalcin / Q000032:analysis; D053495:Osteopontin / Q000032:analysis; D010513:Periodontal Ligament / Q000166:cytology; D016133:Polymerase Chain Reaction; D012313:RNA / Q000032:analysis; D012795:Sialoglycoproteins / Q000032:analysis; D014465:Ultrasonics
D015415:Biomarkers; D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; C546871:IBSP protein, human; D058574:Integrin-Binding Sialoprotein; C493709:RUNX2 protein, human; D012795:Sialoglycoproteins; D015675:Osteocalcin; D053495:Osteopontin; D012313:RNA; D003094:Collagen; D000469:Alkaline Phosphatase