Abstract
Introduction: :
20-hydroxyeicosatetraenoic acid (20-HETE) is an arachidonic acid metabolite produced by Cytochrome P450 (CYP) ω-hydroxylases. We have reported that 20-HETE is angiogenic and 20-HETE synthase inhibitors decrease and even suppress angiogenesis induced by growth factors. In human, the more critical 20-HETE synthases are CYP4A11/4A22 and CYP4F2. Endothelial progenitor cells (EPC) are an important component of neovascularization processes.
Purpose: :
We studied whether the CYP4A-20-HETE system can contribute to the regulation of EPC.
Methods: :
Progenitor cells were isolated from human umbilical cord blood and were identified by AC133 and CD34 expression.
Results: :
We found that these EPC contained both immuno-reactive CYP4A11 and CYP4F2. RT-PCR showed that the mRNA’s coding for these enzymes were also present. When EPC were incubated with arachidonic acid, they formed and secreted 20-HETE. These results indicate that EPC contain an active CYP-20-HETE system. Furthermore, stimulation with 20-HETE increased EPC proliferation and migration indicating that 20-HETE can influence EPC functions. When matrigel plugs containing 20-HETE were injected sc in nude mice, a marked angiogenic response was observed. To study whether the injection of labeled EPC iv results in their accumulation into the 20-HETE-containing plug, we used iron-labeled EPC and determined the presence of the labeled EPC in the plug by MRI and immunohistochemistry. These labeled EPC accumulate into the site of 20-HETE induced neovascularization, which suggests that 20-HETE may induce the homing of EPC. Tube formation by EC seed in matrigel is an in vitro model of angiogenesis. We found that co-culture of EC and EPC results in the tube formation and this effect was inhibited by inhibitors of cytochrome P450 4A/F ω-hydroxylases and by a 20-HETE competitive antagonist. This suggests that 20-HETE is involved in EPC-induced tube formation.
Conclusions: :
The results suggest that the CYP4A-20-HETE system is involved in regulation of EPC functions associated to angiogenesis.
Keywords: eicosanoids • neovascularization • enzymes/enzyme inhibitors