Effects of in vivo static compressive loading on aggrecan and type II and X collagens in the rat growth plate extracellular matrix.
Mechanical loads are essential to normal bone growth, but excessive loads can lead to progressive deformities. In addition, growth plate extracellular matrix remodelling is essential to regulate the normal longitudinal bone growth process and to ensure physiological bone mineralization. In order to investigate the effects of static compression on growth plate extracellular matrix using an in vivo animal model, a loading device was used to precisely apply a compressive stress of 0.2 MPa for two weeks on the seventh caudal vertebra (Cd7) of rats during the pubertal growth spurt. Control, sham and loaded groups were studied. Growth modulation was quantified based on calcein labelling, and three matrix components (type II and X collagens, and aggrecan) were assessed using immunohistochemistry/safranin-O staining. As well, extracellular matrix components and enzymes (MMP-3 and -13, ADAMTS-4 and -5) were studied by qRT-PCR. Loading reduced Cd7 growth by 29% (p<0.05) and 15% (p=0.07) when compared to controls and shams respectively. No significant change could be observed in the mRNA expression of collagens and the proteolytic enzyme MMP-13. However, MMP-3 was significantly increased in the loaded group as compared to the control group (p<0.05). No change was observed in aggrecan and ADAMTS-4 and -5 expression. Low immunostaining for type II and X collagens was observed in 83% of the loaded rats as compared to the control rats. This in vivo study shows that, during pubertal growth spurt, two-week static compression reduced caudal vertebrae growth rates; this mechanical growth modulation occurred with decreased type II and X collagen proteins in the growth plate.
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Mathilde
M
Department of Mechanical Engineering, Ecole Polytechnique de Montréal, P.O. Box 6079, Station Centre-Ville, Montréal, Québec, Canada H3C 3A7. mathilde.cancel@polymtl.ca
Grimard
Guy
G
Thuillard-Crisinel
Delphine
D
Moldovan
Florina
F
Villemure
Isabelle
I
D051722:ADAM Proteins / Q000235:genetics / Q000378:metabolism; D000071121:ADAMTS4 Protein; D000071116:ADAMTS5 Protein; D053674:Aggrecans / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002138:Calibration; D049109:Cell Proliferation; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism*; D024121:Collagen Type X / Q000235:genetics / Q000378:metabolism*; D005109:Extracellular Matrix / Q000201:enzymology / Q000378:metabolism*; D005786:Gene Expression Regulation; D006132:Growth Plate / Q000166:cytology / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D053509:Matrix Metalloproteinase 13 / Q000235:genetics / Q000378:metabolism; D019278:Matrix Metalloproteinase 3 / Q000235:genetics / Q000378:metabolism; D011348:Procollagen N-Endopeptidase / Q000235:genetics / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013131:Spine / Q000166:cytology / Q000378:metabolism; D013314:Stress, Mechanical; D016474:Weight-Bearing
D053674:Aggrecans; D024043:Collagen Type II; D024121:Collagen Type X; D011509:Proteoglycans; D012333:RNA, Messenger; D051722:ADAM Proteins; D000071116:ADAMTS5 Protein; C518696:Adamts5 protein, rat; D053509:Matrix Metalloproteinase 13; C507083:Mmp13 protein, rat; D011348:Procollagen N-Endopeptidase; D019278:Matrix Metalloproteinase 3; D000071121:ADAMTS4 Protein