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To investigate the promoting effects and mechanisms of low intensity pulsed ultrasound (LIPUS) on the migration of bone marrow-derived mesenchymal stem cells (BMSCs). The BMSCs migration was researched from cell and animal experiments. In the cell experiment, the BMSCs was treated using LIPUS (30 mW/cm2, 20 min/day, 2 days), and the wound healing and transwell migration were observed. In the animal experiment, the BMSCs labelled with green fluorescent protein (GFP) were injected into rats with femoral defects via the tail vein (1 × 106/mL). The healing of bone was detected using x-ray and sampled for hematoxylin & eosin (H&E) staining and fluorescence microscopy. About the mechanisms, the cellular F-actin of cytoskeleton was stained with FITC-phalloidin. The changes of BMSCs genes after LIPUS treatment were screened using microarray assay and verified using quantitative real-time polymerase chain reaction (qRT-PCR). The biological processes of those genes were predicted by KEGG analysis. The protein expression levels of FAK, ERK1/2 and myosin II related migration were detected using western blotting. The results showed LIPUS promoted the BMSCs migration (p <.05) without significant temperature changes (p >.05) in vitro and in vivo than control group (p <.05). The cytoskeletal rearrangement was carried out, and the ITGA8 gene related with cell migration was found with high expression after LIPUS treatment (p <.05). FAK inhibitor (PF-573228) and ERK1/2 inhibitor (U0126) were proved, in turn, decreased the BMSCs migration induced using LIPUS (p <.05). LIPUS can promote the BMSCs migration in vitro and in vivo, one mechanism may be related to the activation of FAK-ERK1/2 signalling pathways using LIPUS.Experiments in vivo and in vitro were designed to explore the migration and mechanisms of BMSCs treated using LIPUS. [ABSTRACT FROM AUTHOR]

In terms to investigate the effect of low-intensity pulsed ultrasound (LIPUS) for differentiation of bone marrow mesenchymal stem cells (BMSCs) and the feasibility of simultaneously inducing into osteoblasts and vascular endothelial cells within the cell culture medium in which two inductive agents are added at the same time with or without LIPUS. Cells were divided into a non-induced group, an osteoblast-induced group, a vascular endothelial-induced group, and a bidirectional differentiation-induced group. Each group was further subdivided into LIPUS and non-LIPUS groups. The cell proliferation in each group was measured by MTT assay. Cell morphological and ultrastructural changes were observed by inverted phase contrast microscopy and transmission electron microscopy. The differentiation of BMSCs was detected by confocal microscopy, flow cytometry and quantitative RT-PCR. Results demonstrated that both osteoblast and vascular endothelial cell differentiation markers were expressed in the bidirectional differentiation induction group and early osteogenesis and angiogenesis appeared. The cell proliferation, differentiation rate and expression of osteocalcin and vWF in the LIPUS groups were all significantly higher than those in the corresponding non-LIPUS group (p <.05), suggesting LIPUS treatment can promote the differentiation efficiency and rate of BMSCs, especially in the bidirectional differentiation induction group. This study suggests the combination of LIPUS and dual-inducing agents could induce and accelerate simultaneous differentiation of BMSCs to osteoblasts and vascular endothelial cells. These findings indicate the method could be applied to research on generating vascularized bone tissue with a shape and function that mimics natural bone to accelerate early osteogenesis and angiogenesis. [ABSTRACT FROM AUTHOR]