title: Chondrocyte intracellular calcium, cytoskeletal organization, and gene expression responses to dynamic osmotic loading.
abstract: While chondrocytes in articular cartilage experience dynamic stimuli from joint loading activities, few studies have examined the effects of dynamic osmotic loading on their signaling and biosynthetic activities. We hypothesize that dynamic osmotic loading modulates chondrocyte signaling and gene expression differently than static osmotic loading. With the use of a novel microfluidic device developed in our laboratory, dynamic hypotonic loading (-200 mosM) was applied up to 0.1 Hz and chondrocyte calcium signaling, cytoskeleton organization, and gene expression responses were examined. Chondrocytes exhibited decreasing volume and calcium responses with increasing loading frequency. Phalloidin staining showed osmotic loading-induced changes to the actin cytoskeleton in chondrocytes. Real-time PCR analysis revealed a stimulatory effect of dynamic osmotic loading compared with static osmotic loading. These studies illustrate the utility of the microfluidic device in cell signaling investigations, and their potential role in helping to elucidate mechanisms that mediate chondrocyte mechanotransduction to dynamic stimuli.
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, New York, USA.
authors.forename: Pen-Hsiu Grace
authors.initials: PH
authors.lastname: Chao
authors.forename: Alan C
authors.initials: AC
authors.lastname: West
authors.forename: Clark T
authors.initials: CT
authors.lastname: Hung
mesh_terms: D000199:Actins / Q000378:metabolism; D053674:Aggrecans; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002358:Cartilage, Articular / Q000166:cytology; D002417:Cattle; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism*; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics; D024043:Collagen Type II / Q000235:genetics; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects*; D007038:Hypotonic Solutions / Q000494:pharmacology*; D007424:Intracellular Fluid / Q000378:metabolism*; D037181:Lectins, C-Type / Q000235:genetics; D009995:Osmosis; D012333:RNA, Messenger / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D000199:Actins; D053674:Aggrecans; D011508:Chondroitin Sulfate Proteoglycans; D024043:Collagen Type II; D016326:Extracellular Matrix Proteins; D007038:Hypotonic Solutions; D037181:Lectins, C-Type; D012333:RNA, Messenger; D004533:Egtazic Acid; D019284:Thapsigargin; D002118:Calcium