Mechanical injury of cartilage explants causes specific time‐dependent changes in chondrocyte gene expression

Abstract

Objective. Joint injury in young adults leads to an increased risk of developing osteoarthritis (OA) later in life. This study was undertaken to determine if injurious mechanical compression of cartilage explants results in changes at the level of gene transcription that may lead to subsequent degradation of the cartilage.Methods. Cartilage was explanted from the femoropatellar groove of newborn calves. Levels of messenger RNA encoding matrix molecules, proteases, their natural inhibitors, transcription factors, and cytokines were assessed in free swelling control cultures as compared with cartilage cultures at 1, 2, 4, 6, 12, and 24 hours after application of a single injurious compression.Results. Gene-expression levels measured in noninjured, free swelling cartilage varied over 5 orders of magnitude. Matrix molecules were the most highly expressed of the genes tested, while cytokines, matrix metalloproteinases (MMPs), aggrecanases (ADAMTS-5), and transcription factors showed lower expression levels. Matrix molecules showed little change in expression after injurious compression, whereas MMP-3 increased ϳ250-fold, ADAMTS-5 increased ϳ40-fold, and tissue inhibitor of metalloproteinases 1 increased ϳ12-fold above the levels in free swelling cultures. Genes typically used as internal controls, GAPDH and ␤-actin, increased expression levels ϳ4-fold after injury, making them unsuitable for use as normalization genes in this study. The expression levels of tumor necrosis factor ␣ and interleukin-1␤, cytokines known to be involved in the progression of OA, did not change in the chondrocytes after injury. Conclusion.Changes in the level of gene expression after mechanical injury are gene specific and time dependent. The quantity of specific proteins may be altered as a result of these changes in gene expression, which may eventually lead to degradation at the tissue level and cause a compromise in cartilage structure and function.

A sodium dodecyl sulfate–polyacrylamide gel electrophoresis–liquid chromatography tandem mass spectrometry analysis of bovine cartilage tissue response to mechanical compression injury and the inflammatory cytokines tumor necrosis factor α and interleukin‐1β

“…In contrast, compression injury caused the loss of cell membrane integrity and the release of intracellular proteins, which may cause changes in gene expression and/or trigger apoptosis in neighboring cells. Release of matrix proteins and protein fragments following compression injury suggests damage to the PCM and ECM, consistent with reported decreases in tissue compression and shear stiffness (2,6,14,21,43). Damage to the matrix may also lead to changes in cell-matrix interactions, which could be responsible for apoptosis, for changes in gene expression, or for the decrease in the ability of the remaining viable cells to up-regulate biosynthesis in response to anabolic loading (2,6,14,21,43).…”

Computational investigation of in situ chondrocyte deformation and actin cytoskeleton remodelling under physiological loading

“…Numerous experimental studies have examined the effect of abnormal mechanical loads, resulting in damaged cartilage, on chondrocyte viability and biosynthetic activity. It has been shown that mechanical injury to cartilage explants results in chondrocyte apoptosis with a loss of glycosaminoglycans [58] and changes in gene expression [59]. Similarly, Borelli Jr. et al [60] have shown that in vivo chondrocyte apoptosis can be caused by a single impact load.…”

Regulation of Chondrocytic Gene Expression by Biomechanical Signals

“…14 Dynamic compression has been shown to upregulate expression of anabolic genes such as ACAN, COL2 α1 (COL2A1), and tissue inhibitor of metalloproteinase 3 (TIMP3) 15 while downregulating specific genes of the matrix metalloproteinase (MMP) family. 4,9,15,16 More importantly, compressive forces at low magnitudes have been shown to be antiinflammatory in nature. This is evidenced by the findings that when chondrocytes seeded into agarose hydrogel scaffolds were stimulated by exogenous interleukin-1β (IL-1β), sinusoidal form compression at 15% strain suppressed aggrecanase 1 (a disintegrin-like and metalloprotease domain (reprolysin-type) with thrombospondin type I motifs 4 [ADAMTS4]) and aggrecanase 2 (ADAMTS5) but not MMP3 gene expression.…”

“…[21][22][23] Similarly, long-term (24-48 hours) compressive strain of 25% to 50% is catabolic and substantially downregulates expression of ACAN and COL2A1 and upregulates MMP3, MMP9, MMP13, and ADAMTS4 expression to induce cartilage destruction. 16,24 Contrary to dynamic loading, static compression induces an initial accumulation of interstitial hydrostatic pressure within the cartilage; however, this pressure reaches an equilibrium stasis due to stress relaxation of the tissue. 3 Static compression invariably downregulates anabolic gene expression 4,12,16 and upregulates catabolic (MMP3, MMP9, MMP13, and ADAMTS4) 4 and inflammatory (tumor necrosis factor-α [TNF-α; TNFA], COX2/PTGS2, iNOS/NOS2A).…”

“…16,24 Contrary to dynamic loading, static compression induces an initial accumulation of interstitial hydrostatic pressure within the cartilage; however, this pressure reaches an equilibrium stasis due to stress relaxation of the tissue. 3 Static compression invariably downregulates anabolic gene expression 4,12,16 and upregulates catabolic (MMP3, MMP9, MMP13, and ADAMTS4) 4 and inflammatory (tumor necrosis factor-α [TNF-α; TNFA], COX2/PTGS2, iNOS/NOS2A). 4,6 gene expression.…”