Modulation of extracellular matrix synthesis and alkaline phosphatase activity of periodontal ligament cells by mechanical stress.
BACKGROUND
Loss of occlusal function has been reported to induce atrophic changes in the periodontal ligament. It is likely that mechanical stress triggers the biological response of periodontal ligament. However, there have been few reports studying the correlation between mechanical stress of varying magnitude and periodontal ligament cell activities such as extracellular matrix (ECM) synthesis.


OBJECTIVE
The objective of this study is to clarify the influence of the mechanical stress on changes in mRNA expression levels of type I collagen and decorin genes, as well as alkaline phosphatase (ALP) activity in response to mechanical stress of varying magnitude.


METHODS
Bovine periodontal ligament cells were cultured on flexible-bottomed culture plates and placed on the BioFlex Loading Stations. Cells were elongated at 6 cycles/min (5 s on and 5 s off) at each of six levels of stretch (0.2, 1.0, 2.0, 3.0, 10, 18% increase in the surface area of the bottom) for 48 h. We measured mRNA expression levels of type I collagen and decorin genes using quantitative reverse transcription-polymerase chain reaction (RT-PCR), and ALP activity in periodontal ligament cell culture under cyclic mechanical stretching.


RESULTS
Mechanical tensional stress of low magnitude induced the increase of both type I collagen and decorin mRNA expression without changing ALP activity in periodontal ligament cells. Mechanical tensional stress of high magnitude induced the increase of type I collagen and decorin mRNA expression while decreasing ALP activity.


CONCLUSIONS
These results suggest that different magnitude of tensional force induces different responses from periodontal ligament cells, and that mechanical stress plays an important role in remodeling and functional regulation of periodontal ligament.
Ozaki
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S
Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Sciences, Gradute School, Tokyo Medical and Dental University, Tokyo, Japan. shu.orts@tmd.ac.jp
Kaneko
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S
Podyma-Inoue
K A
KA
Yanagishita
M
M
Soma
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K
D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D018929:Cell Culture Techniques; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism*; D058575:Decorin; D005109:Extracellular Matrix / Q000201:enzymology; D016326:Extracellular Matrix Proteins; D010513:Periodontal Ligament / Q000166:cytology / Q000201:enzymology*; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013314:Stress, Mechanical; D013997:Time Factors
D024042:Collagen Type I; D058575:Decorin; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D012333:RNA, Messenger; D000469:Alkaline Phosphatase