Living cartilage tissue 3D-printed

STEM cells have been demonstrated to survive 3D printing and then grow into cartilage cells for the first time.

Top surgeons couldn’t tell the difference between real human cartilage and the 3D bioprinted cartilage, which could be used to treat osteoarthritis.

Regenerative medicine is a current area of research which aims to replace or regenerate human body cells, tissues or organs in order to combat a wide range of diseases. This field is no exception when it comes to the technological revolution in 3D printing, and 3D ‘bioprinting’ is anticipated to revolutionise available medical treatments. It is hoped that the use of different cells and supporting biological materials can be used to develop ‘bioinks’, from which tissues and organs can be printed on demand.

Cartilage is one such tissue, and provides a rubber-like padding to protect the ends of bones and joints. As cartilage breaks down or wears over time, the stress on joints increases. This is thought to lead to a painful condition called osteoarthritis, which is difficult to treat. Current treatment methods often involve multiple surgical procedures, the success of which can depend on the quality and quantity of the patient’s cells that are available.

Now, for the first time, Swedish researchers have printed cells into 3D structures with the ability to survive the bioprinting process and grow into cartilage tissue. This tissue is similar to that found in the human body, and so could potentially be used to increase cell availability for treatment.

Lead researcher Stina Simonsson, of The University of Gothenburg, said: “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.”

Their process involved harvesting cartilage cells from people undergoing knee surgery, before taking them to the laboratory and turning them into stem cells, which can change, or differentiate, into many different types of cell. The team then had to find a way to ensure that cells survived printing, and then could grow and differentiate into cartilage.

Simonsson said: “Each individual stem cell was 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 – our theory is that we managed to trick the cells into thinking that they aren’t alone.”

Experienced surgeons examined the tissue produced, and remarked that it was extremely similar to human cartilage. Just like normal cartilage, the lab-grown material contained type II collagen, which makes up around half of all protein in cartilage, while under the microscope the cells appeared to be perfectly formed.

Once fully developed, this technique could be used to produce patient-specific large quantities of cartilage for use in treating osteoarthritis. According to Simonsson, however, this will not become a reality without further research to ensure safety.

She said: “The structure of the cellulose we used might not be optimal for use in the human body. 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.”