Bioengineers have been steadily advancing toward the goal of building lab-grown organs out of a patient’s own cells, but a few major challenges remain. One of them is making vasculature, the blood vessel plumbing system that delivers nutrients and remove waste from the cells on the inside of a mass of tissue. Without these blood vessels, interior cells quickly suffocate and die.
Scientists can already grow thin layers of cells, so one proposed solution to the vasculature problem is to “print” the cells layer by layer, leaving openings for blood vessels as necessary. But this method leaves seams, and when blood is pumped through the vessels, it pushes those seams apart.
Bioengineers from the University of Pennsylvania have turned the problem inside out by using a 3D printer called a RepRap to make templates of blood vessel networks out of sugar. Once the networks are encased in a block of cells, the sugar can be dissolved, leaving a functional vascular network behind.