Left to right: Sheep meniscus; 3-D model of meniscus obtained from laser scanning; 3-D printed anatomically correct meniscus scaffold. (Credit: Lab of Dr. Jeremy Mao)
Researchers from Columbia University Medical Center have shown that a 3D printed implant might one day be used to treat torn menisci in the knee. Currently, there is no effective treatment for torn menisci except for completely removing them, which greatly increases the subsequent risk of developing osteoarthritis. The researchers used MRI data to 3D-print a scaffold, which was then infused with human growth factors to regenerate a new lining and these were implanted in sheep’s knees.
The process starts with obtaining an MRI scan of the intact meniscus in the undamaged knee. The scan data are then used to 3D-print a scaffold in the exact shape of the meniscus, down to a resolution of 10 microns. The printing process takes about thirty minutes and the scaffold is made of polycaprolactone, a biodegradable polymer. The scaffold is infused with two recombinant human proteins encapsulated in slow-dissolving polymeric microspheres. These proteins attract stem cells from the body inducing them to form meniscal tissue. They contain connective growth factor which is released first to stimulate production of the outer meniscus and transforming growth factor β3 which is later released to stimulate production of the inner meniscus. The protein-infused scaffold is inserted into the knee, after which the meniscus regenerates in about four to six weeks, while the scaffold itself eventually dissolves.
Implantation was successfully performed in a handful of sheep, who were walking normally after three months, and whose menisci showed structural and mechanical properties very similar to those of natural menisci. Studies of long term results are underway, and hopefully these can be transferred to humans with equal success.
Study abstract in Science Translational Medicine: Protein-releasing polymeric scaffolds induce fibrochondrocytic differentiation of endogenous cells for knee meniscus regeneration in sheep…
Press release: Meniscus Regenerated with 3-D Printed Implant…