Abstract
Background - Trafficking of transplanted endothelial progenitor cells (EPCs) to an ischemic organ is a critical step in neovascularization. This study was performed to elucidate the molecular mechanism of EPC trafficking in terms of adhesion molecules. Methods and Results - Using murine hindlimb ischemia model, we examined expressions of E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and platelet-endothelial cell adhesion molecule-1 (PECAM-1) in ischemic muscle by immunofluorescence. ICAM-1 was overexpressed in ischemic muscle compared with nonischemic muscle, whereas expressions of E-selectin, VCAM-1, and PECAM-1 did not show that much difference. ICAM-1 was also upregulated by hypoxia in murine endothelial cells (ECs) as assessed by immunoblot and flow cytometry. EPCs were attached to ECs specifically through ICAM-1/β-2 integrin interaction in vitro. When EPCs were labeled with fluorescent dye or radioisotope (Tc-99m-HMPAO) and systemically administrated in vivo, EPCs preferentially homed to ischemic muscle. By blocking ICAM-1, EPCs entrapment to ischemic limb in vivo was significantly reduced and neovascularization induced by EPC transplantation was attenuated. Conclusions - ICAM-1 is upregulated by ischemia, and this is closely associated with EPCs entrapment to ischemic limb. Our findings suggest that ICAM-1 expression might be important in regulating the process of neovascularization through its ability to recruit EPCs.
Original language | English |
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Pages (from-to) | 1066-1072 |
Number of pages | 7 |
Journal | Arteriosclerosis, Thrombosis, and Vascular Biology |
Volume | 26 |
Issue number | 5 |
DOIs | |
State | Published - May 2006 |
Keywords
- Adhesion molecules
- Angiogenesis
- Endothelial progenitor cells
- Endothelium
- Ischemia