Hemopexin protects endothelial integrity by promoting endothelial progenitor cells differentiation and new blood vessels formation through heme oxygenase-1 pathway

Abstract

Objective To investigate the effect of hemopexin (HPX) on promoting endothelial progenitor cells (EPCs) differentiation and neovascularization to protect endothelial integrity from toxic heme through heme oxygenase-1 (HO-1) pathway. Methods Rat EPCs were cultured routinely, and randomly divided into 5 groups (at their logarithmic phase): control group, HPX group, heme group, heme+HPX group, and Zn protoporphyrin IX (ZnppIX) group. Cells in the control group were cultured in M199 culture medium with 10% fetal calf serum, 5 μg/mL basic fibroblast growth factor and 1% penicillin-streptomycin, and 20 μmol/L HPX, 20 μmol/L heme, 20 μmol/L heme-HPX compound, and 20 μmol/L heme-HPX compound and 10 μmol/L ZnppIX were added in the culture mediums of HPX group, heme group, heme+HPX group and ZnppIX group, respectively. Cells were harvested after 24 h of culture; HO-1 expression was detected by Western blotting; differentiation of EPCs to mature endothelial cells was investigated using von Willebrand factor (vWF) immunofluorescence; vasculogenic ability was tested using angiogenesis assay on Matrigel Basement Membrane Matirx. Results As compared with that in the control group (0.60±0.15), HO-1 expression increased significantly in heme group (1.07±0.03,P<0.05); as compared with the heme group, the HO-1 expression in the heme+HPX group (1.57±0.06) significantly increased (P<0.05). As compared with those in the control group, the EPCs number was smaller, CD31 and vWF expressions were decreased and immunofluorescence results were weaker in the heme group; as compared with those in the control group, the EPCs number was larger, CD31 and vWF expressions were increased and immunofluorescence results were stronger in the heme+HPX group. As compared with that in the control group ([41.0±7.18]/field), the number of tube 1ike structure formation in the heme group ([25.0±3.67]/field) was significantly smaller (P<0.05); as compared with that in the heme group, the number of tube 1ike structure formation in the heme+HPX group ([58.6±2.70]/field) was significantly larger (P<0.05). Conclusion HPX shows significant effect on promoting EPCs differentiation and new blood vessels formation to protect the endothelial integrity from toxic heme by increasing the HO-1expression. Key words: Hemopexin; Heme oxygenase-1; Endothelial progenitor cell