Effect of CXCR4 pretreated with ultrasound-exposed microbubbles on accelerating homing of bone marrow mesenchymal stem cells to ischemic myocardium in AMI rats

ABSTRACT

Objective: To investigate the role and potential mechanism of CXCR4 in promoting targeted homing of bone marrow mesenchymal stem cells (BMSCs) with ultrasound-exposed microbubbles (UM) pretreatment. Methods: Third generation BMSCs were divided into four groups control group, ultrasound (US) group, UM group and ultrasound-exposed microbubbles plus catalase group. RT-PCR and western blot were performed to determine the levels of CXCR4 mRNA transcription and protein expression, respectively. Third generation BMSCs were labeled with Fluo-α/AM and divided into three groups control group, US group and UM group, and fluorescence intensities in the cells were observed immediately, 5 min and 15 min after intervention under fluorescence microscope. The calcium iron levels in the cells were analyzed. BMSCs were divided into five group group A without calcium in the medium, group B, group C, group D and group E containing calcium chloride with concentration of l mol, 2 mol, 4 mol, anti-calcium-sensing receptor antibody, respectively. RT-PCR and western blot were performed to determine the levels of CXCR4 mRNA transcription and proteins expression of the third generation BMSCs of each group, respectively. Results: The levels of CXCR4 mRNA transcription and protein expression between US group and control group had no statistically significant difference (P > 0.05) shown by RT-PCR and western blot; the transcription level in the UM group was significantly higher than that in US group and control group (P 0.05), which in the cells of UM group was significantly higher than that in the cells of both US group and control group (P < 0.05). Compared to group A, expressions of CXCR4 of group B to D were significantly increased in concentration-dependent manner showed by RT-PCR and western blot (P < 0.05). Compared to group C, expressions of CXCR4 of group E were significantly decreased (P < 0.05). Conclusions: UM can promote the influx of calcium in BMSCs and increase mRNA transcription and protein expression of CXCR4. The latter may partly be caused by influx of calcium.