Prolonged Application of High Fluid Shear to Chondrocytes Recapitulates Gene Expression Profiles Associated with Osteoarthritis

Abstract

BackgroundExcessive mechanical loading of articular cartilage producing hydrostatic stress, tensile strain and fluid flow leads to irreversible cartilage erosion and osteoarthritic (OA) disease. Since application of high fluid shear to chondrocytes recapitulates some of the earmarks of OA, we aimed to screen the gene expression profiles of shear-activated chondrocytes and assess potential similarities with OA chondrocytes.Methodology/Principal FindingsUsing a cDNA microarray technology, we screened the differentially-regulated genes in human T/C-28a2 chondrocytes subjected to high fluid shear (20 dyn/cm2) for 48 h and 72 h relative to static controls. Confirmation of the expression patterns of select genes was obtained by qRT-PCR. Using significance analysis of microarrays with a 5% false discovery rate, 71 and 60 non-redundant transcripts were identified to be ≥2-fold up-regulated and ≤0.6-fold down-regulated, respectively, in sheared chondrocytes. Published data sets indicate that 42 of these genes, which are related to extracellular matrix/degradation, cell proliferation/differentiation, inflammation and cell survival/death, are differentially-regulated in OA chondrocytes. In view of the pivotal role of cyclooxygenase-2 (COX-2) in the pathogenesis and/or progression of OA in vivo and regulation of shear-induced inflammation and apoptosis in vitro, we identified a collection of genes that are either up- or down-regulated by shear-induced COX-2. COX-2 and L-prostaglandin D synthase (L-PGDS) induce reactive oxygen species production, and negatively regulate genes of the histone and cell cycle families, which may play a critical role in chondrocyte death.Conclusions/SignificanceProlonged application of high fluid shear stress to chondrocytes recapitulates gene expression profiles associated with osteoarthritis. Our data suggest a potential link between exposure of chondrocytes/cartilage to abnormal mechanical loading and the pathogenesis/progression of OA.

The Antagonistic Actions of Endogenous Interleukin-1β and 15-Deoxy-Δ12,14-prostaglandin J2 Regulate the Temporal Synthesis of Matrix Metalloproteinase-9 in Sheared Chondrocytes

“…Excessive chronic or repetitive mechanical loading of articular cartilage producing hydrostatic stress, tensile strain, and fluid flow (1) has been implicated in the development and progression of OA (2). Indeed, prolonged application of high fluid shear to human chondrocytes in vitro recapitulates gene expression profiles associated with OA in vivo (3). Although OA is classified as a noninflammatory joint disease, the progressive erosion of cartilage involves the action of cytokines and prostaglandins (PGs), which are capable of inducing the expression of matrix-degrading enzymes such as matrix metalloproteinases (MMPs) (4).…”

An integrated microfluidic device for characterizing chondrocyte metabolism in response to distinct levels of fluid flow stimulus

“…According to the results, the described device generated shear stresses spanning over at least four orders of magnitude (0.007-15.4 dyne/cm 2 ). This range of shear stresses started from an extremely low level comparable to interstitial shear stress level (Park et al 2009;Chen et al 2012;Rutkowski and Swartz 2007) to a high level which was deemed to be injurious for chondrocytes (Lee et al 2003; Healy et al 2005;Zhu et al 2010b). It also had a broader scope than previous methods and had the advantage of controlling stimulus intensity in a particular range.…”

“…Because water makes up approximately 70-85 % of cartilage weight, accordingly interstitial flow always exists in cartilage tissues undergoing dynamic compression, imparting extremely low shear stress on the cell surface (Rutkowski and Swartz 2007). It has also been reported that the superficial and transitional zones of articular cartilage are remarkably exposed to fluid flow stimulus (Zhu et al 2010b). In addition, fluid flow-induced shear stress is closely relevant with the regulation of articular cartilage metabolism and the pathophysiologic process of articular cartilage (Das et al 1997).…”

“…The effect of high fluid shear stress (*20 dyne/cm 2 ) on chondrocytes has been more widely concerned by researchers recently (Healy et al 2005;Wang et al 2011c;Zhu et al 2010b), because excessive mechanical forces are implicated in the development and progression of osteoarthritis (OA). IL-6, as one of the proinflammatory cytokines, can be detected in OA chondrocytes (Ryu et al 2011).…”

“…By changing the inlet channel resistance of the microchambers and input flow rate, more extensive levels can be generated. Based on this system, we investigate chondrocyte morphological and metabolic responses to fluid stimulus that ranged in magnitude from the interstitial shear stress level in vivo to a level beyond a physiological fluid flow in chondrocytes (Healy et al 2005;Wang et al 2010;Zhu et al 2010b). Furthermore, IL-6 expression in chondrocytes under distinct levels of fluid flow stimulus was assayed.…”