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The effect of mechanical forces on adipogenic differentiation

Sharafi, Parisa
Numerous intra and extra cellular factors take role in differentiation of cell towards a given lineage. These factors have crucial role in cell-cell and cell-environment interactions. In this study, the aim is to investigate the effect of mechanical forces on the adipogenic differentiation of preadipocytes and mesenchymal stem cells in an in vitro model. Human preadipocytes and mesenchymal stem cells were embedded in 2 % agarose discs. According to the stress-relaxation test results it was observed that initial mechanical properties of agarose-mesenchymal stem cell (MSC) discs did not change compared to acellular agarose whereas those of preadipocytes decreased significantly. The discs with cells were exposed to compression under different weights (1.4 ± 0.2 g, 7.5 ± 0.2 g, and 14.6 ± 0.3 g.) continuously in differentiation medium for 21 days. The control discs were treated with differentiation medium without any compressive weight on top of them. After 21 days, total ribonucleic acids (RNA) have been isolated. Adipogenic differentiation was investigated via reverse transcription coupled quantitative polymerase chain reaction (PCR). The expression of peroxisome proliferators-activated receptors (PPAR-gamma), CCAAT-enhancer binding protein (C/EBP-Beta), leptin, adiponectin, adipophilin and human stearoyl-CoA desaturase (hSCD) have been assessed as adipogenic markers. Differentiation to adipocytes has been further investigated by histochemical Sudan IV staining and immunochemistry and compared to control group. Decrease in the expression of adipogenic factors, size and number of lipid droplets were observed for both MSCs and preadipocytes subjected to compression in agarose discs. The decreases were correlated with the level of mechanical stress. The highest depletion of gene expression was observed in leptin and C/EBP. From our results, it was shown for the first time that mechanical stress impaired the adipogenic differentiation of MSCs and preadipocytes in agarose discs. However, the differentiation pathways should be further investigated.