Blood vessel density and cell proliferation assessment with respect to the tumor group explored.

<p>Immunofluorescence staining of CD31 and Ki67 in a typical tumor arising from mild hypoxic (3% O₂) grown U87-MG cells ((A)—CD31 / (E)–Ki67) and from normoxic grown (21% O₂) tumor ((B)—CD31 / (F)–Ki67) once a size of 8μL is reached. Nucleus staining was performed using DAPI (Blue). Scale bar = 100μm. Quantitative vessel density analysis (C) and average vessel area (D) revealed, on average, 668 ± 50 vessels/mm² with an area of 46 ± 5 μm² in the tumor arising from the cells cultured under mild hypoxia versus 919 ± 35 vessels/mm² with an area of 33 ± 2 μm² in the tumor arising from cells cultured under normoxia [p<0.001 for vessel number (**) and p<0.03 for area (*)]. However, the vascular surface average is not significantly different between both groups and is ~3%. The quantitative analysis of Ki67 positive cells is presented in frame (G), and despite non-significant (p = 0.107) on average, 829 ± 138 positive cells/mm² were counted in the tumor arising from the cells cultures in mild hypoxia condition versus 1178 ± 59 positive cells/mm² in the tumor arising from cells cultured under normoxia.