Low intensity pulsed ultrasound promotes the migration of bone marrow- derived mesenchymal stem cells via activating FAK-ERK1/2 signalling pathway

Abstract

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.

GRAPHICAL ABSTRACT

Experiments in vivo and in vitro were designed to explore the migration and mechanisms of BMSCs treated using LIPUS.

Keywords:

• Cell migration
• bone marrow-derived mesenchymal stem cells
• low intensity pulsed ultrasound
• signalling pathway
• femoral defect

Disclosure statement

The authors report no conflicts of interest and are responsible for the content and writing of the manuscript.

Additional information

Funding

This study was supported by the National Basic Research Program of China Funding [No. 2011CB707900], the National Natural Science Fund by the Chinese National Science Foundation [No. 81127901, 11574039, 31571453 and 11274404].