3D printing is now capable of producing prosthetics and generating cartilage tissue from stem cells. Led by researchers at Sweden's Sahlgrenska Academy, a study published in Scientific Reports reviews 3D bioprinting as a nest step in using human cells to print cartilage that is identical to human-harvested cartilage.

Collaborating with experts in 3D bioprinting at Chalmers University of Technology in Göteborg, Sweden, the researchers harvested cartilage cells from patients undergoing knee surgery and manipulated them in a laboratory to form stem cells. The stem cells were then expanded in nanofibrillated cellulose to be printable in a 3D bioprinter. After being printed out, the cells were treated with growth factors to develop into cartilage tissue.

"In nature, the differentiation of stem cells into cartilage is a simple process, but it's much more complicated to accomplish in a test tube. We're the first to succeed with it, and we did so without any animal testing whatsoever," said Stina Simonsson, associate professor of cell biology, who lead the research team's efforts. "We investigated various methods and combined different growth factors. Each individual stem cell is encased in nanocellulose, which allows it to survive the process of being printed into a 3D structure. We also harvested mediums from other cells that contain the signals that stem cells use to communicate with each other so called conditioned medium. In layman's terms, our theory is that we managed to trick the cells into thinking that they aren't alone.”

Comparable to normal human cartilage, the 3D-printed cartilage contained type 2 collagen that provided a structure seen in human cartilage. The cartilage was examined by surgeons, who found no difference between 3D-printed variety and real cartilage. Researchers believe the 3D bioprinting of cartilage from a patient’s own cells could be used to treat osteoarthritis and other damaged cartilage within the body.

"The structure of the cellulose we used might not be optimal for use in the human body,” said Simonsson. “Before we begin to explore the possibility of incorporating the use of 3D-bioprinted cartilage into the surgical treatment of patients, we need to find another material that can be broken down and absorbed by the body so that only the endogenous cartilage remains, the most important thing for use in a clinical setting is safety.”