A multi-arm bioprinter that can print cartilage. (Ozbolat Lab/Penn State)

Strands of cow cartilage substitute for ink in a 3D bioprinting process that may one day create cartilage patches for worn out joints. A cartilage strand substitutes for ink in a 3D printing process. Using a specially designed prototype nozzle that can hold and feed the cartilage strand, the 3D printer lays down rows of cartilage strands in any pattern the researchers choose.

After about half an hour, the cartilage patch self-adheres enough to move to a petri dish. The researchers put the patch in nutrient media to allow it to further integrate into a single piece of tissue. Eventually, the strands fully attach and fuse together. The strands can be manufactured in any length.