Future 3D printing could fix damaged cartilage in knees, noses and ears
Researchers at Wallenberg Wood Science Center in Sweden have found a way to produce cartilage tissue by 3-D bioprinting an ink containing human cells
Having successfully tested the cartilage tissue in an in vivo mouse model, Swedish researchers believe that the development could one day lead to precisely printed implants to heal damaged noses, ears and knees.
“Three-dimensional bioprinting is a disruptive technology and is expected to revolutionise tissue engineering and regenerative medicine,” says Paul Gatenholm, Ph.D. “Our team’s interest is in working with plastic surgeons to create cartilage to repair damage from injuries or cancer. We work with the ear and the nose, which are parts of the body that surgeons today have a hard time repairing. But hopefully, they’ll one day be able to fix them with a 3-D printer and a bioink made out of a patient’s own cells.”
Gatenholm’s team first had to develop an ink with living human cells that would keep its shape after printing, as previously printed materials would collapse into an amorphous pile.
To create a new bio-ink, polysaccharides from brown algae and tiny cellulose fibrils from wood or made by bacteria were mixed with human chondrocytes, which are cells that build up cartilage. Using this mixture, the researchers were able to print living cells in a specific architecture, such as an ear shape, that maintained its form even after printing. The printed cells also produced cartilage in a laboratory dish.
“Under in vitro conditions, we have to change the nutrient-filled liquid that the material sits in every other day and add growth factors,” Gatenholm says. “It’s a very artificial environment.” Tells Gatenholm. So the next step was to move the research from a lab dish to a living system.
Printed tissue samples were implanted in mice where the cells survived and produced cartilage. To then boost the number of cells – another hurdle in tissue engineering – the researchers mixed the chondrocytes with human mesenchymal stem cells from bone marrow. Previous research has indicated that stem cells spur primary cells to proliferate more than they would alone. Preliminary data from in vivo testing over 60 days show the combination encourages chondrocyte and cartilage production.
Further preclinical work needs to be done before moving on to human trials and Gatenholm is working is currently working with a plastic surgeon to anticipate and address practical and regulatory issues.
In addition to cartilage printing, Gatenholm’s team is working with a cosmetic company to develop 3-D bioprinted human skin. Since cosmetic companies in Europe are now prohibited from testing cosmetics on animals, it’s hoped this printed skin can be used to try out makeup, anti-wrinkling techniques and strategies to prevent sun damage.