RESUMEN
BACKGROUND/AIMS: In articular cartilage, chondrocytes are the predominant cell type. A long-term stay in space can lead to bone loss and cartilage breakdown. Due to the poor regenerative capacity of cartilage, this may impair the crewmembers' mobility and influence mission activities. Beside microgravity other factors such as cosmic radiation and vibration might be important for cartilage degeneration. Vibration at different frequencies showed various effects on cartilage in vivo, but knowledge about its impact on chondrocytes in vitro is sparse. METHODS: Human chondrocytes were exposed to a vibration device, simulating the vibration profile occurring during parabolic flights, for 24 h (VIB) and compared to static controls. Phase-contrast microscopy, immunofluorescence, F-actin and TUNEL staining as well as quantitative real-time PCR were performed to examine effects on morphology, cell viability and shape as well as gene expression. The results were compared to earlier studies using semantic analyses. RESULTS: No morphological changes or cytoskeletal alterations were observed in VIB and no apoptotic cells were found. A reorganization and increase in fibronectin were detected in VIB samples by immunofluorescence technique. PXN, VCL, ANXA1, ANXA2, BAX, and BCL2 revealed differential regulations. CONCLUSION: Long-term VIB did not damage human chondrocytes in vitro. The reduction of ANXA2, and up-regulation of ANXA1, PXN and VCL mRNAs suggest that long-term vibration might even positively influence cultured chondrocytes.
Asunto(s)
Condrocitos/metabolismo , Vibración , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Anexina A2/genética , Anexina A2/metabolismo , Línea Celular , Condrocitos/citología , Condrocitos/patología , Colágeno Tipo II/genética , Colágeno Tipo II/metabolismo , Redes Reguladoras de Genes , Humanos , Molécula 1 de Adhesión Intercelular/genética , Molécula 1 de Adhesión Intercelular/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Vimentina/genética , Vimentina/metabolismoRESUMEN
BACKGROUND/AIMS: Spaceflight negatively influences the function of cartilage tissue in vivo. In vitro human chondrocytes exhibit an altered gene expression of inflammation markers after a two-hour exposure to vibration. Little is known about the impact of long-term vibration on chondrocytes. METHODS: Human cartilage cells were exposed for up to 24 h (VIB) on a specialised vibration platform (Vibraplex) simulating the vibration profile which occurs during parabolic flights and compared to static control conditions (CON). Afterwards, they were investigated by phase-contrast microscopy, rhodamine phalloidin staining, microarray analysis, qPCR and western blot analysis. RESULTS: Morphological investigations revealed no changes between CON and VIB chondrocytes. F-Actin staining showed no alterations of the cytoskeleton in VIB compared with CON cells. DAPI and TUNEL staining did not identify apoptotic cells. ICAM-1 was elevated and vimentin, beta-tubulin and osteopontin proteins were significantly reduced in VIB compared to CON cells. qPCR of cytoskeletal genes, ITGB1, SOX3, SOX5, SOX9 did not reveal differential regulations. Microarray analysis detected 13 differentially expressed genes, mostly indicating unspecific stimulations. Pathway analyses demonstrated interactions of PSMD4 and CNOT7 with ICAM. CONCLUSIONS: Long-term vibration did not damage human chondrocytes in vitro. The reduction of osteopontin protein and the down-regulation of PSMD4 and TBX15 gene expression suggest that in vitro long-term vibration might even positively influence cultured chondrocytes.