3D printing creates new way to treat diseases(2)

Likewise, when using prosthetics, doctors don't know for sure whether the piece will fit until they attempt to implant it during surgery. Sometimes, prosthetics are modified during an operation. But this is risky, and can make operations longer and threaten patients' health.

Materials that are biocompatible with the human body should be used in 3-D printed models such as artificial joints. In some cases, such as when a patient is recovering from a serious injury, materials that are capable of being absorbed into the body should be used, Lin says.

For example, he says, if a person suffers a serious injury and loses a part of a bone, doctors will implant a tissue-engineering scaffold around the bone to help the bone tissue to regenerate. Bone cells will grow along the scaffold, filling parts of the fractured bone.

The fracture will eventually heal, and the scaffold will gradually disappear over time. "The functional need has a very high requirement for the structure," Lin says.

A porous structure is needed, because the cells need to absorb nutrition through the scaffold and also grow through it, he says. The size of pores cannot be too large or small, in order to ensure that the cells grow properly.

"We have developed a new technique for 3-D printing such scaffolds," Lin says. "Usually, during the 3-D printing process, additive materials will be heated and extruded from the print head, but the products will be solid inside, unable to meet the requirements," Lin said.

"One of our researchers developed a new technique. He dissolved the material in a solvent and squeezed the fluid out in an environment that was-30 C. Once printed, the fluid freezes immediately. During the freezing process, the additive material and the solvent separate and form a lot of pores. It's just like the process of freezing toufu.

"Then he removed the solvent and got the porous structure of the additive material ... There are big pores and small pores in the scaffold, which are very helpful to the growth of cells. This is our unique technique."

Another new, cutting edge technology being developed is the use of viable cells as additive materials to produce a three-dimensional living space for cells.

Usually, cells cannot live long after leaving the body and die within two or three generations. Nurtured cells usually grow along the walls of a two-dimensional surface, which is different from the environment of the human body.

Researchers found that cells react differently in two-dimensional spaces than they do in three-dimensional ones, so the different dimensions will affect the development of medicines.

For example, cancer cells spread on the walls of two-dimensional spaces but when 3D printed, they form a ball, researchers at the Bio-manufacturing Center found. They also tested the cells' reaction to some anti-cancer drugs in two-dimensional situations, and the results were different.

"So it seems for cells, a three-dimensional space is more like the environment of the human body," Lin said.

Lin says his researchers see a lot of potential for using 3-D printing technology in to create viable cells and other organs.

"With this technology, we set a real high goal for long-term development. We want to 3-D print organs. Although it will be very difficult, but without such a goal, how can we develop new advanced technology?"