An idea that once seemed absurd is now looking entirely possible, for researchers at Columbia University Medical Center have managed to successfully implant 3D-printed cartilage in sheep.
Specifically, they replaced the meniscus, which is a piece of C-shaped cartilage, the tearing of which is one of the most common knee injuries, according to the Mayo Clinic.
At present, there is no way to regenerate damaged menisci and in severe cases, they must be removed, which can bring an athlete's career to an early end for it leaves him without a shock absorber between the femur and tibia, according to study leader Jeremy Mao, DDS, PhD.
Attempts to replace damaged menisci using tissue from other parts of the patient's body or from cadavers have been generally unsuccessful and such procedures are considered high-risk in the medical community.
Using MRI scans of the intact meniscus in the sheep's healthy knee, which closely resembles that of a human, Dr. Mao converted the scans into a 3D image, which was then programmed into the printer.
In 30 minutes, the 3D printer was able to produce a scaffold that captured the shape of the meniscus within 10 microns of its actual size.
Hardly the same consistency of a real meniscus, the scaffold is made of polycaprolactone, a biodegradable polymer used in surgical thread.
To make it compatible with the body, researchers infused it with two recombinant human proteins called connective growth factor (CTGF) and transforming growth factor β3 (TGFβ3).
After surgically implanting the protein-infused scaffold into the sheep's knee, Dr. Mao and his team saw the meniscus regenerated in four to six weeks (11 sheep were used), with the scaffold having dissolved and its rudiments eliminated from the body.
The sheep were walking normally three months after surgery.
The research was published in the online edition of Science Translational Medicine.
