Abstract
BACKGROUND: Macrophages are present before the onset of blood flow, but very little is known about their function in vascular development. We have developed a technique to concurrently label both endothelial cells and macrophages for time-lapse microscopy using co-injection of fluorescently conjugated acetylated low-density lipoprotein (AcLDL) and phagocytic dye PKH26-PCL.
RESULTS: We characterize double-labeled cells to confirm specific labeling of macrophages. Double-labeled cells circulate, roll along the endothelium, and extravasate from vessels. Most observed macrophages are integrated into the vessel wall, showing an endothelial-like morphology. We used transgenic quail that express a fluorescent protein driven by the endothelial-specific promoter Tie1 in conjugation with the phagocytic dye to analyze these cells. Circulating PKH26-PCL-labeled cells are mostly Tie1-, but those which have integrated into the vessel wall are largely Tie1+. The endothelial-like phagocytic cells were generally stationary during normal vascular development. We, therefore, induced vascular remodeling and found that these cells could be recruited to sites of remodeling.
CONCLUSIONS: The active interaction of endothelial cells and macrophages support the hypothesis that these cells are involved in vascular remodeling. The presence of phagocytic endothelial-like cells suggests either a myeloid-origin to certain endothelial cells or that circulating endothelial cells/hematopoietic stem cells have phagocytic capacity.
Original language | English |
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Pages (from-to) | 1423-31 |
Number of pages | 9 |
Journal | Developmental Dynamics |
Volume | 241 |
Issue number | 9 |
DOIs | |
Publication status | Published - Sept 2012 |
Externally published | Yes |
Keywords
- Animals
- Blood Vessels/cytology
- Coturnix/embryology
- Embryo, Nonmammalian
- Embryonic Development/physiology
- Endothelium, Vascular/cytology
- Fluorescent Dyes/pharmacology
- Macrophages/cytology
- Microscopy/methods
- Organic Chemicals/pharmacology
- Time-Lapse Imaging/methods