(A) The blood-brain barrier separates the brain (grey or white background) from the the blood (pink background) inside the blood vessels in the brain. The main components of the barrier are smooth muscle cells (SM; narrow pink layers), endothelial cells (EC; blue), and astrocytes (green/yellow). The different isoforms of apolipoprotein E (ApoE; purple ovals) help to move beta-amyloid peptides (Aß; black) from the brain to the blood with different levels of efficiency, and with the help of high-density lipoproteins (HDL; yellow). (B) In the bioreactor, smooth muscle cells, endothelial cells, and astrocytes are grown on an artificial tubular scaffold (left) to mimic blood vessels. Fluid can then be pumped through the resulting bioengineered structure to mimic in vivo conditions and explore a range of cardiovascular phenomena. (C) Cross-sectional view of the bioengineered blood vessel. Smooth muscle cells and endothelial cells grow inside the scaffold (circular black structure), while astrocytes are grown on the outside of the scaffold. Panel A is redrawn from https://www.cldinc.com/portfolio/blood-brain-barrier-illustration/.