[Chemokine receptor 7 promotes the paracrine of hepatocyte growth factor by mesenchymal stem cells via inhibitor of differentiation-1].

Objective: To investigate the possible mechanism of mesenchymal stem cells (MSC) secreting hepatocyte growth factor (HGF).

Methods: (1) C57BL/6 mouse mesenchymal stem cells (mMSC) were cultured in vitro, and mMSC with high expression of chemokine receptor 7 (CXCR7) were transduced by lentivirus plasmid. Blank control group and empty carrier control group were set at the same time. After 20 generations of cell culture, the transfection efficiency was identified by fluorescence microscopy and flow cytometry. The mRNA expression levels of CXCR7 in mMSC were detected by real-time fluorescent quantitative reverse transcription-polymerase chain reaction (RT-PCR). (2) mMSC with passage number 4-6 were divided into MSC control group [MSC-blank group, 100 μg/L lipopolysaccharide (LPS) was added to wild-type MSC], highly expressed CXCR7 group (MSC-OE-CXCR7 group, 100 μg/L LPS was added to mMSC transduced by lentivirus plasmid with high expression of CXCR7), highly expressed CXCR7 control group (MSC-OENC-CXCR7 group, 100 μg/L LPS was added to mMSC transduced by no load lentivirus plasmid), CXCR4 inhibitor group (MSC-IE-CXCR4 group, 100 μg/L LPS was added to mMSC after 0.1 mg/L CXCR4 inhibitor TC14012 pretreatment for 24 hours), and CXCR4 inhibitor control group (MSC-IENC-CXCR4 group, 100 μg/L LPS was added to mMSC after DMEM culture medium with equal amount of TC14012 pretreatment for 24 hours). Cells in each group were collected after treatment with LPS, and mRNA expression of inhibitor of differentiation-1 (ID-1) was detected by RT-PCR. The cell supernatant was collected, and the levels of HGF were detected by enzyme linked immunosorbent assay (ELISA).

Results: (1) The high expression of CXCR7 for mMSC which were transduced through lentivirus plasmid were successfully constructed detected by fluorescence microscope and flow cytometry. Compared with the blank control group, the expression of CXCR7 mRNA in the lentivirus with high expression of CXCR7 group was significantly increased (2: 5.81±0.97 vs. 1.02±0.12, P < 0.05). There was no significant difference in CXCR7 mRNA expression between the empty carrier control group and the blank control group (2: 0.95±0.22 vs. 1.02±0.12, P > 0.05). (2) Compared with the MSC-blank group, high expression of CXCR7 in MSC-OE-CXCR7 group or inhibition of CXCR4 in MSC-IE-CXCR4 group could induce high expression of ID-1 mRNA in mMSC (2: 5.56±0.66, 2.47±0.58 vs. 1.00±0.10, both P < 0.05) and increase HGF exocrine level (ng/L: 632.02±149.98, 217.21±40.53 vs. 108.53±24.62, both P < 0.05). However, there were no significant differences in ID-1 mRNA expression and HGF exocrine level of mMSC among MSC-OENC-CXCR7 group, MSC-IENC-CXCR4 group and MSC-blank group [ID-1 mRNA (2): 1.01±0.27, 1.21±0.32 vs. 1.00±0.10, HGF (ng/L): 133.56±25.19, 107.11±25.30 vs. 108.53±24.62, both P > 0.05].

Conclusions: High expression of CXCR7 or inhibition of CXCR4 in MSC can increase the expression of ID-1 and promote the secretion of HGF, thus promoting pulmonary microvascular endothelial repair.