Dec 11, 2014 | By Kira
The meniscus, a small piece of cartilage lining our knee joint, may not be the most well known body part, yet it plays an essential role in proper leg function. Unfortunately, meniscus injuries are quite common, and can often lead to the debilitating pain of arthritis.
Luckily, researchers at Columbia University Medical Center have devised a way to replace damaged menisci using a personalized 3D printed implant infused with proteins that stimulate stem cells, prompting the body to regenerate a brand new, functional lining.
image via MDguidelines
The treatment has been successfully tested in sheep, whose knee structure resembles our own, and could provide the first effective and long-lasting repair of damaged menisci, which occur in millions of Americans each year.
The process, led by Dr. Jeremy Mao, DDS, PhD, involves taking an MRI scan of the sheep's intact meniscus in the undamaged knee. The scan is then converted into a 3D image and sent to a 3D printer, which produces an implant, or a scaffold, in the exact shape and dimension of the original meniscus. 3D printers allow a resolution of 10 microns, less than the width of a human hair, and much more accurate than what could be achieved by hand. The scaffold takes about 30 minutes to print and is made of polycaprolactone, a biodegradable polymer that is also used to make surgical sutures.
Left to right: sheep meniscus, 3D model of meniscus obtained from laser scanning, and 3D printed meniscus scaffod. Image via Lab of Dr. Jeremy Mao.
Dr. Mao explains that the scaffold is infused with two human proteins delivered in sequence. The connective growth factor (CTGF) and transforming growth factor (β3 (TGFβ3) proteins stimulate the body's internal stem cells, prompting them to regenerate the meniscal tissue.
It is vital that the proteins are released in specific areas of the scaffold in sequential order. To do this, the researchers encapsulated the proteins in two types of slow-dissolving polymeric microspheres, first releasing CTGF, to stimulate the production of the outer meniscus, and then TGFβ3 to stimulate the inner meniscus. After significant growth, the scaffold and proteins are inserted into the damaged knee.
Unlike classic tissue engineering, where stem cells are harvested from the body, manipulated in the lab, and then returned to the patient, Dr. Mao says they are "jumpstarting the process within the body, using factors that promote endogenous stem cells for tissue regeneration."
The process was tested in 11 sheep, with a random selection receiving the protein-infused 3D scaffold, and the rest receiving a 3D scaffold without protein. In six weeks on average, the sheep that received the protein-infused treatment were able to undergo weight bearing and locomotion, just as in normal sheep. Thanks to the polycaprolactone, the scaffold eventually dissolves and is eliminated by the body, leaving no trace. In a postmortem analysis, the regenerated meniscus was found to have structural and mechanical properties very similar to the natural meniscus, indicating possible long-lasting effects.
Right: Regenerated sheep meniscus after scaffold with proteins was inserted. Left: Regenerated meniscus without proteins.
The successful implementation of this therapy is great news for both doctors, and those with knee injuries. "At present, there is little that orthopedists can do to regenerate a torn knee meniscus," said Dr. Mao. "Some small tears can be sewn back in place, but larger tears have to be surgically removed." Removal may help reduce the pain and swelling, but it leaves the knee without a natural shock absorber and increases the risk of arthritis.
Meniscus transplants created with the tissue from other parts of the body or from cadavers are also an option, however that procedure has a low success rate and carries significant risks. Dr. Mao's 3D print approach, on the other hand, seems to be a clear solution.
"We envision that personalized meniscus scaffolds, from initial MRI to 3D printing, could be completed within days," said Dr. Mao. The personalized scaffolds can be shipped to hospitals within a week, reducing the overall time for surgery and recovery. The researchers hope to begin clinical trials once funding is in place.
"This research, although preliminary, demonstrates the potential for an innovative approach to meniscus regeneration," said co-author Dr. Scott Rodeo, sports medicine orthopedic surgeon and researcher and the Hospital for Special Surgery in New York City. The research article was published on December 10th in the online edition of Science Translational Medicine. Along with Dr. Mao and Dro. Rodeo, Dr. Lisa Ann Fortier, professor of large animal surgery at Cornell University College of Veterinary Medicine in Ithaca also partook in the research.
"As a veterinary orthopedic surgeon-scientist on this multi-disciplinary team, I foresee the added bonus of having new techniques for treating veterinary patients with torn knee meniscus," she said.
The study was funded by grants from the National Institute of Health, the Arthroscopy Association of North America, the American Orthopedic Society for Sports Medicine, and the Harry M. Zweig Foundation.
Posted in 3D Printing Applications
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Maybe earlier you think
milu wrote at 12/13/2014 7:05:31 PM:
One day I may have my torn meniscus back :)
alvaro wrote at 12/11/2014 4:46:58 PM:
That's amazing and wonderful ! soon : teeth , livers, kidneys ,hearts etc
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