Beneficial Effects of Low Frequency Vibration on Human Chondrocytes in Vitro

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.

Pathway Analysis Hints Towards Beneficial Effects of Long-Term Vibration on Human Chondrocytes

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.

Environmental hazards of pesticides from pineapple crop production in the Río Jiménez watershed (Caribbean Coast, Costa Rica)

This study aimed to characterize environmental hazards of pesticides from pineapple production in riparian communities along the Jiménez River watershed. To achieve our objectives riparian ecological quality indices on riparian habitat and macroinvertebrate assemblages were combined with toxicity assays, fish biomarkers, physico-chemical water analysis and pesticide environmental hazards. During two consecutive years and two periods (July and October), three reference and four impacted sites were monitored. The ecological quality of benthic macroinvertebrates and of riparian habitats deteriorated from the reference sites downstream to the polluted reaches along the Jiménez River area affected by pineapple plantations. The toxicity of water to Daphnia magna also increased towards downstream reaches. Biomarkers of fish of the species Poecilia gillii and Bryconamericus scleroparius transplanted across the studied sites evidenced a clear anticholinergic effect towards downstream sites as well as increased levels of lipid peroxidation. Different pesticide residues were frequently detected in water samples collected across the Jiménez River watershed with herbicides (ametryn, bromacil, diuron), organophosphorus insecticides (diazinon and ethoprophos) and triazole fungicides being the greatest reaching levels above 1 μg L(-1) in downstream sites. Principal component and environmental hazard analysis of physico-chemical and biological responses established clear relationships among habitat deterioration and the ecological quality of macroinvertebrate communities, high levels of herbicides and poor plant growth, high levels of organophosphorus insecticides in water and anticholinesterase effects on fish, D. magna mortality and deterioration of macroinvertebrate communities. Fungicide and herbicide residue levels were also related with high levels of lipid peroxidation and high activities of glutathione S transferase in fish liver, respectively. These results indicated, thus, that riparian habitat deterioration due to deforestation and land use for agriculture and pesticide contamination are affecting river ecosystems.