Fig. 3. Cell cycle analysis and TUNEL staining of cells cultured under hypoxic conditions. HDMECs were cultured under hypoxic conditions for 0, 6 or 24 hours as indicated. (A) For cell cycle analysis, DNA was stained using propidium iodide and analysed by flow cytometry. Hypoxic culture resulted in an increased number of cells arrested at the G0/G1 phases and an increased level of DNA fragmentation (blue profile). (B) TUNEL staining was performed on the same batch of cells used for cell cycle analysis. Apple green staining of nuclei corresponds to apoptotic cells. Hypoxic culture led to an increased number of apoptotic cells (original magnification: x250). All experiments were performed at least three times and produced similar results.