3-D bioprinting is a form of rapid prototyping adapted to the tissue engineering industry. Printers assemble tissues from ink containing cells and supporting materials of various types. Given a suitable recipe, the result is a functional tissue quite close to the real thing in structure and function. The interesting part of this open access paper is not that the team bioprinted small-scale model hearts as their proof of concept, given that these are not fully functional heart tissues capable of the electrical coordination required to exhibit a heart beat, and nor is it that they used materials personalized to a specific patient. Rather, it is that they demonstrate the ability to bioprint networks of small blood vessels sufficient to support the interior cells of a thick tissue.
This is an important advance, even given that it is not the full microvascular networks of capillaries found in natural tissue. This matter of blood vessels is a major challenge in the tissue engineering community. Cells need a supply of blood in order to survive, and that supply must be carried by blood vessels for any distance much over a millimeter. Finding a reliable way to incorporate blood vessel networks into