Torn Meniscus? There's Hope. Thank a Sheep.

This is going to make my husband very happy.

The news today that meniscus -- that pesky knee tissue that rips so easily -- can now be regrown using a 3D printed imprint.

Say what?  I fail to see how a piece of paper produced in a computer printer can do anything more than, well, rip itself.  But researchers at Columbia University Medical Center have devised a way to replace the knee’s protective lining, called the meniscus, using a personalized 3D-printed implant, or scaffold, infused with human growth factors that prompt the body to regenerate the lining on its own, according to newswise.com.

The therapy, successfully tested in sheep, could provide the first effective and long-lasting repair of damaged menisci, which occur in millions of Americans each year and can lead to debilitating arthritis.

My husband, a star athlete in his youth, tore his meniscus about 15 years (and 5,000,000 complaints) ago, forcing him to give up his beloved tennis (where he was an eternal tournament winner, even against younger men).

I didn't have much sympathy for him, until I tore mine this summer.

"At present, there’s little that orthopedists can do to regenerate a torn knee meniscus,” said study leader Jeremy Mao, DDS, PhD, the Edwin S. Robinson Professor of Dentistry (in Orthopedic Surgery) at the Medical Center.

“Some small tears can be sewn back in place, but larger tears have to be surgically removed. While removal helps reduce pain and swelling, it leaves the knee without the natural shock absorber between the femur and tibia, which greatly increases the risk of arthritis," he added.

Larry had laser surgery right after he tore it but back then, the game was pretty much over and recently he's been going for cortisone shots.


A damaged meniscus can be replaced with a meniscal transplant, using tissue from other parts of the body or from cadavers. That procedure, however, has a low success rate and carries significant risks. Approximately one million meniscus surgeries are performed in the United States each year.

Enter 3D printing.

Dr. Mao’s approach starts with MRI scans of the intact meniscus in the undamaged knee. The scans are 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 (less than the width of a human hair). The scaffold, which takes about 30 minutes to print, is made of polycaprolactone, a biodegradable polymer that is also used to make surgical sutures.

The scaffold is infused with two recombinant human proteins: 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.

For a meniscus to properly form, however, the proteins must be released in specific areas of the scaffold in a specific order. This is accomplished by encapsulating the proteins in two types of slow-dissolving polymeric microspheres, first releasing CTGF (to stimulate production of the outer meniscus) and then TGFβ3 (to stimulate production of the inner meniscus). Finally, the protein-infused scaffold is inserted into the knee. In sheep, the meniscus regenerates in about four to six weeks. Eventually, the scaffold dissolves and is eliminated by the body.

"This is a departure from classic tissue engineering, in which stems cells are harvested from the body, manipulated in the laboratory, and then returned to the patient—an approach that has met with limited success,” said Dr. Mao. “In contrast, we’re jumpstarting the process within the body, using factors that promote endogenous stem cells for tissue regeneration.”

"This research, although preliminary, demonstrates the potential for an innovative approach to meniscus regeneration," said co-author Scott Rodeo, MD, sports medicine orthopedic surgeon and researcher at Hospital for Special Surgery in New York City. "This would potentially be applicable to the many patients who undergo meniscus removal each year."

Will it work in humans?  It was tested in sheep, who have knees (who knew?) closest to humans'.  A small group of sheep were given the procedure and now, walk normally.  Researchers are currently conducting studies to determine whether the regenerated tissue is long-lasting.

Is it real hope, or just a pipe dream?  I guess we won't know for a while.  I just know that Larry is going to be first in line when they offer it to humans.  Just hope he won't "baaaaa!" in his sleep.





 

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