title: Mechanical compression alters gene expression and extracellular matrix synthesis by chondrocytes cultured in collagen I gels.
abstract: Articular cartilage responds to its mechanical environment through altered cell metabolism and matrix synthesis. In this study, isolated articular chondrocytes were cultured in collagen type I gels and exposed to uniaxial static compression of 0%, 25%, or 50% of original thickness for 0.5, 4, and 24 h, and to oscillatory (25 +/- 4%, 1 Hz) compression for 24 h. The cellular response was assessed through competitive and real-time RT-PCR to quantify expression of genes for collagen type I, collagen type II, and aggrecan core protein, and through radiolabelled proline and sulfate incorporation to quantify protein and proteoglycan synthesis rates. Static compression for 24 h inhibited expression of collagen I and II mRNAs and inhibited 3H-proline and 35S-sulfate incorporation. The mRNA expression exhibited transient fluctuations at intermediate time points. Oscillatory compression had no effect upon mRNA expression, and 24 h after release from static compression, there was no difference in collagen II or aggrecan mRNA, while there was an inhibition of collagen I. We conclude that the chondrocytes maintained some aspects of their ability to sense and respond to static compression, despite a biochemical and mechanical environment which is different from that in tissue. This suggests that mechanical stimuli may be useful in modulating chondrocyte metabolism in tissue engineering systems using fibrillar protein scaffolds.
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta 30332-0535, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Hunter
authors.forename: Stacy M
authors.initials: SM
authors.lastname: Imler
authors.forename: Prasanna
authors.initials: P
authors.lastname: Malaviya
authors.forename: Robert M
authors.initials: RM
authors.lastname: Nerem
authors.forename: Marc E
authors.initials: ME
authors.lastname: Levenston
mesh_terms: D053674:Aggrecans; D000818:Animals; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D024042:Collagen Type I / Q000235:genetics; D024043:Collagen Type II / Q000235:genetics; D019245:Compressive Strength; D005109:Extracellular Matrix / Q000378:metabolism; D016326:Extracellular Matrix Proteins; D005782:Gels; D015870:Gene Expression; D037181:Lectins, C-Type; D008422:Materials Testing; D011509:Proteoglycans / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D053674:Aggrecans; D001672:Biocompatible Materials; D024042:Collagen Type I; D024043:Collagen Type II; D016326:Extracellular Matrix Proteins; D005782:Gels; D037181:Lectins, C-Type; D011509:Proteoglycans; D012333:RNA, Messenger