But one challenge with printing out organs—a heart, for example—is that they require connections to blood vessels, nerves and other tissue in order to function properly. So although it is possible to get mouse heart cells to twitch with an electrical jolt, it is not yet possible to grow the necessary connections to the rest of the body while the new heart is put in place. Regenerated skin tissue, however, is different: After it is grafted it absorbs plasma, and blood vessels eventually grow into it.
Vladimir Mironov, an assistant professor in the department of Regenerative Medicine and Cell Biology at the Medical University of South Carolina, says the big contribution from Atala is the use of living cells. "It's a new page in tissue engineering, the use of cells in vivo," he says. By focusing on skin, Mironov says Atala has avoided some of the problems associated with printing whole organs, and by printing living cells directly on the wound, the fluid suspending the cells is absorbed.
Mironov says one part about which he is skeptical at this point is how well the process works on large areas and on different skin types. Another issue is how to grow enough cells if a burn covers a very large area; the cells would have to be taken from the patient's skin so as to avoid rejection, so they would likely need to be grown in advance of printing them, which can take some time. That may not be practical in some cases.