Figure 3: Effect of hypoxia on HUVEC tubular network maintained with and without ALDHbr cells in transwell cultures. (A)HUVEC cells plated on extracellular matrix in the bottom of transwell culture plates were allowed to form tubular networks under normoxic conditions. Transwell cultures were then incubated under hypoxic conditions for 24h either with (B) or without (C) ALDHbr cells added to the top chamber of the transwell cultures. HUVEC maintained defined branching structures in transwells with ALDHbr cells (B), while tubules without ALDHbr cells (C) retract (thin arrows) and areas of cell necrosis were present (wide arrow).