Researchers have honed in on a way to replace the meniscus, using a personalized 3D-printed implant in sheep, according to a study published online December 10, 2014, in Science Translational Medicine. The therapy, successfully tested in sheep, could provide the first effective and long-lasting repair of damaged menisci.
“At present, there’s little that orthopedists can do to regenerate a torn knee meniscus,” said lead study author Jeremy Mao, DDS, PhD, the Edwin S. Robinson Professor of Dentistry in Orthopedic Surgery at Columbia University Medical Center in New York. “In contrast, we’re jumpstarting the process within the body, using factors that promote endogenous stem cells for tissue regeneration.”
Jeremy Mao, DDS, PhD
This process was tested on 11 sheep. Knees of sheep were chosen because of their close resemblance to the human knee. In this study, the sheep were randomized to have part of their knee meniscus replaced with a protein-infused 3D scaffold or a 3D scaffold without protein.
Dr. Mao’s approach starts with MRI scans of the intact meniscus in the undamaged knee, which is then converted into a 3D image. Data from the image are then used to drive a 3D printer, which produces a scaffold in the exact shape of the meniscus, down to a resolution of 10 microns. The scaffold is infused with connective growth factor (CTGF) and transforming growth factor β3 (TGFβ3). Dr. Mao’s team found that sequential delivery of these two proteins attracts existing stem cells from the body and induces them to form meniscal tissue.
After three months, treated animals were walking normally. In a postmortem analysis, the researchers found that the regenerated meniscus in the treatment group had structural and mechanical properties very similar to those of natural meniscus. In sheep, the meniscus regenerates at a rate of about 4 to 6 weeks. Eventually, the scaffold dissolves and is eliminated by the body.