Cellular Velcro: In a new approach to bottom-up tissue engineering, two different cell types spontaneously assemble themselves into three-dimensional microstructures like this one when their surfaces are studded with sticky single strands of DNA. Because the DNA on the red cells is complementary to that on the green cells, they naturally stick together, holding the cells in close proximity.
Credit: Bertozzi Lab

While this new method isn't the first to tackle tissue engineering from the bottom up, Gartner says that it's the only one capable of fine enough resolution to define how individual cells interact with their neighbors. And even if this technique turns out not to scale up well, he says, it could in principle provide structural building blocks for use in other emerging bottom-up approaches, such as layer-by-layer tissue printing or laser manipulation.

Khademhosseini says that it's too early to tell whether the new technique will eventually produce tissues suitable for use in regenerative medicine. "It has a lot of potential, and it may provide therapies in the future, but other challenges need to be overcome to make a clinically viable product," he says. For example, it remains to be seen where the cells to grow the tissue would come from, and how the body would generate new blood vessels to feed the transplanted tissue.

Dan Dimitrijevich, director of the Human Tissue and Cell Engineering Laboratories at the University of North Texas Health Science Center, is more skeptical. He doubts that the new approach will be able to generate stable, safe, and functional tissues that hold up when transplanted into an actual living organism. "It's interesting science," he says, "but as far as tissue engineering, it's really stretching."

Even if it doesn't pan out in terms of regenerative medicine, Gartner believes that the technique could still prove useful as a tool for studying how different cell types communicate--for example, in the process of generating a tumor. "This now gives us a new tool to take these structures out of a human host--where obviously they're very difficult to study for a number of technical and ethical reasons--and put them into a flask where we can study them in detail over long periods of time," he says.