"Bio-Ink" Printer Creates Muscle and Bone Cells from Adult Stem Cells

By Tracy Staedter, Discovery News, January 9, 2007

For the first time, using one type of adult stem cell, scientists have discovered a means by which to produce bone and muscle.

The technique coaxes stem cells to differentiate by using an ink-jet printer to lay down patterns of “bio-ink”.

Over time, the technique could make it easier to produce replacement muscle and bone for people suffering from trauma or tissue diseases, not to mention help scientists better understand how the human body creates different tissues from stem cells.

"We would like the printer to customize the therapy for each patient. We could design a pattern based on the defect," said research leader Julie, a post-doctoral fellow at Carnegie Mellon University in Pittsburgh.

The field of tissue engineering moves one step closer to functioning the same way that the body does by using the “bio-ink” printer says Julie.

Stimulating cells to not only proliferate and grow but mature into specific kinds of cells, scientists know that different concentrations and patterns of cellular growth factors — proteins such as collagen and fibrin — affect the final result. Cells such as bone, skin, blood, and nerve, cells are among the many possibilities.

Researchers are optimistic that mimicking the process will get them closer to some answers, although, they still have questions about how growth factors stimulate a cellular response.

Instead of ink, the printer produces a growth factor, but behaves and looks comparable to an ordinary ink-jet printer in every other way.

Taking a glass slide, Julie and her team use the machine to print the growth factor onto the surface of the glass. Depending on their intended result, they vary the concentration and pattern of the bio-ink.

The glass slide is then dipped into a solution consisting of adult stem cells. The cells have a natural affinity for the growth factor matrix and react to the concentration and pattern by dividing and multiplying into muscle or bone.

In order to figure out which combination best leads to which tissue, Julie and her team experimented with different concentrations and patterns.

"Lots of people have used ink-jet printing techniques within tissue engineering. But they would be the first to apply the printing technique to stem cell differentiation," said Brian, professor of materials science at the Manchester Materials Science Center in England.

Julie says that other techniques involve taking cells that have already been stimulated to grow into one kind of tissue or another and then printing those.

In previous approaches, each time a new color was desired, the print cartridge had to be changed.

But he print cartridge doesn’t have to be changed with the new method. The machine can lay a foundation for the correct tissue and let the cells do the rest, just like the human body.

"Although the printing has improved the resolution both chemically and spatially, it's still two-dimensional," said Brian.

"Real organisms are three-dimensional and cells communicate by transmitting various biochemicals in three dimensions. The communication channels on a sheet of paper that you've printed are very different and very limited," he said.

More complex versions of the tissue printer are being tested. Julie’s team is currently working on one that can print several growth factors in a three-dimensional space using multiple print heads.