Figure 7
Immunofluorescence staining of CD34+ cells and formation of capillary structures on Matrigel. Representative culture of CD34+ cells after 10 days of growth on collagen-fibronectin–coated chamber slide stained with anti-CD31(b) and anti-vWF (c). a, CD31 staining performed on CD34+ cells 24 hours after plating revealed no signal expression. At the same time in culture, vWF antigens were also absent. b, Light CD31 expression along the cell-cell contact borders. At the time of culture, usually 20% to 30% of CD34+ cells stained positively for CD31. c, Typical granular perinuclear positivity for vWF staining on CD34+ cells. Its signal intensity and distribution, but not its expression, are comparable to mature endothelial cells isolated from the adult human aorta (data not shown), confirming the immature endothelial phenotype of CD34+ cells. d, Capillary structures formed by CD34+/CD31+ cells 24 hours after seeding on Matrigel. The CD34+/CD31+ cells form tube-like structures, with long vessel-like extensions interconnecting occasional clumps of cells. Scale bars: 17 μm (a, b, c), 250 μm (d).
