An ambitious form of 3-D printing is envisaged by these researchers: they want to develop the means to print out replacement cartilage tissue in place inside the body by use of minimally invasive techniques such as the introduction of a catheter threaded with the print head machinery that deposits cells and matrix materials:

Creating artificial cartilage requires three main elements: stem cells, biological factors to make the cells grow into cartilage, and a scaffold to give the tissue its shape. [The] 3-D printing approach achieves all three by extruding thin layers of stem cells embedded in a solution that retains its shape and provides growth factors. The ultimate vision is to give doctors a tool they can thread through a catheter to print new cartilage right where it's needed in the patient's body.

In another significant step, [researchers have] successfully used the 3-D printing method to produce the first "tissue-on-a-chip" replica of the bone-cartilage interface. Housing 96 blocks of living human tissue 4 millimeters across by 8 millimeters deep, the chip could serve as a test-bed for researchers to learn about how osteoarthritis develops and develop new drugs. "With more testing, I think we'll be able to use our platform to simulate osteoarthritis, which would be extremely useful since scientists really know very little about how the disease develops. Osteoarthritis has a severe impact on quality of life, and there is an urgent need to understand the origin of the disease and develop effective treatments. We hope that the methods we're developing will really make a difference, both in the study of the disease and, ultimately, in treatments for people with cartilage degeneration or joint injuries."