Development of the Human Acellular Vessel, or HAV, starts by taking living cells from a human blood vessel and placing them onto a tube-shaped frame. These vascular cells are kept alive in an organ chamber, growing around the tube-shaped lattice. Over time, the lattice that was used to seed the original vascular cells dissolves, and scientists remove the original cells so the new vessel doesn't cause an immune response when it's implanted. What is left is a solid, tubular structure made of human vascular material that looks and acts like a blood vessel -- thus, the bio-engineered and newly-grown blood vessel, or HAV. (USU medical illustration by Sofia Echelmeyer)