Stable changing fluid shear stress promotes osteogenesis

Abstract

AbstractObjectiveBone marrow cells encounter various chemical and mechanical stimuli from the internal environment. In vivo, fluid shear stress (FSS) is one of the primary mechanical stimuli that affect bone marrow-derived mesenchymal stem cells (BMCs) activity. Since various cases of FSS influence BMCs activity differently, the purpose of this study is to determine how BMC activity in osteogenesis and osteoclastgenesis is affected by stable and unstable changing FSS.MethodBMCs samples from the femur of the mouse, divided in to three groups: stimulate by stable changing FSS, unstable changing FSS, and no FSS. RT-PCR would be applied to detect OPG, RANKL, ALP, OCN, RUNX2, and RANK of all the samples at the 3rd day. Alizarin red staining and TRAP staining would be applied to test all the samples at the 6th day.ResultsThe S group samples showed the lowest level in RANKL mRNA and showed the highest level in OPG mRNA. RANKL/OPG mRNA in the S group was the smallest during three groups. Comparing with the C group samples, RUNX2 mRNA in the S group was increased significantly. RANK mRNA in the C group was three times more than S group. S group had the largest area of mineralized nodules, and largest number of area ≥100µm, ≥500µm2 or ≥1000µm2. The area of positive TRAP stain in S group was the smallest among three groups.ConclusionStable changing FSS significantly increases osteogenesis relating to OPG-RANKL-RANK pathway. Compared with unstable changing FSS, stable changing FSS afford a more appropriate stimulation to osteogenesis.AbbreviationsALPAlkaline phosphataseBMCsBone marrow-derived mesenchymal stem cellsCx43Connexin 43C3aComplement Component 3aJNKc-Jun N-terminal kinaseERKExtracellular regulated protein kinasesERK5Extracellular-signal-regulated kinaseFSSFluid shear stressFasLFirst apoptosis signal LigandGSK3βGlycogen synthase kinase 3βLPALysophosphatidic acidMSCsMesenchymal stem cellsM-CSFMacrophage colony-stimulating factorMCP-1Monocyte chemoattractant protein-1RANKReceptor Activator of Nuclear Factor κ BRANKLReceptor activator of nuclear factor κ B ligandRUNX2Runt-related transcription factor 2P2Y2RReceptor of P2Y2LGR4Repeat-containing G-protein-coupled receptor 4SemaSemaphorinsTRAPTartrate-Resistant Acid AhosphataseTRPM7Transient receptor potential cation channel subfamily M member 7TRAFsTumornecrosisfactorreceptor associatedfactorsOPGOsteoprotegerinOCNOsteocalcinOPNOsteopontin