Abstract 247: Heparanase-overexpressed Mesenchymal Stem Cells Enhances Angiogenesis Via Hypoxia-inducible Factor-2α/Vascular Endothelial Growth Factor Receptor-2 Pathway
Background: Heparanase is an endoglycosidase involved in the cleavage of the heparin sulfate and plays important role in tumor metastasis and angiogenesis. Here we showed heparanase - overexpressed mesenchymal stem cells (MSCs) promoted angiogenesis in rat model after femoral artery ligation, and its underlying mechanism was via endothelial cells migration by Hypoxia-Inducible Factor-2α (HIF-2α) / vascular endothelial growth factor receptor-2 (Flk-1) pathway and collateral formation.
Methods: MSCs were transduced with heparanase (MSC heparanase), control cells were either nontransduced (MSCWT) or transduced with empty vector (MSCNull). The effect of human umbilical vein endothelial cells (HUVECs) migration, tube formation and the role for heparanase were determined by transwell, matrigel and arterial rings asaay after co-culture with MSCheparanase, MSCNull and MSCWT conditioned medium. Moreover, right femoral artery was occluded in rats receiving PBS or MSCNull or MSCheparanase, blood flow recovery was assessed by laser-Doppler imaging (LDI) before surgery, immediately after operation, as well as 3, 7 and 14 days after occlusion, capillary density was measured at 14 days after occlusion.
Results: In vivo, the group receiving MSCheparanase had a fast recovery of blood flow at 7 days after occlusion and more capillary densities at 14 days after occlusion. In vitro, HUVECs treated with MSCheparanase conditioned medium exhibited increased formation of capillary-like structures and promoted migration, compared with HUVECs treated with MSCNull conditioned medium. All effects of MSCheparanase conditioned medium were abolished by knockdown of HIF-2α and flk-1 with a selective shRNA and were absent in HUVECs. Mechanism studies revealed that heparanase increased the cellular accumulation of HIF-2α protein and affects its nuclear translocation, which regulates flk-1 and its downstream proteins: p38 and HSP27 expression.
Conclusions: These findings identify heparanse as a key regulator in MSCs induced angiogenesis and collateral formation. Heparanse up-regulates HIF-2α and mediates Flk-1/p38/HSP27 pathway, which is necessary for angiogenesis and collateral artery network.
Author Disclosures: X. Hu: None L. Zhang: None J. Jin: None H. Cheng: None H. Chen: None J. Wang: None.
- © 2014 by American Heart Association, Inc.