According to a news release issued by Columbia University Medical Center, its researchers have developed a strategy in which meniscus can be replaced using a personalized 3D-printed implant, or scaffold, infused with human growth factors that encourage the body to regenerate the lining on its own. The release notes that the therapy has been successfully tested in sheep and could potentially provide the first effective, and long-lasting, repair of damaged menisci.

The paper appears in the online edition of Science Translational Medicine

Watch a video of the 3D implant

According to study leader Jeremy Mao, DDS, PhD, Edwin S. Robinson, professor of Dentistry (in Orthopedic Surgery) at the Medical Center, currently there is little orthopedists can do to regenerate a torn knee meniscus,“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.”

The release reports that a damaged meniscus can be replaced with a meniscal transplant using tissue from other parts of the body or from cadavers. Yet, the procedure has a reportedly low success rate and carries significant risks.

The release notes that Mao’s strategy encompasses the use of MRI scans of the intact meniscus in the undamaged knee. The scans are converted into a 3D image, and data from the image is 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 comprised of polycaprolactone.

The scaffold is then infused with two recombinant human proteins that include connective growth factor (CTGF) and transforming growth factor ?3 (TGF?3). 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.

The release states that in order for the meniscus to properly form, the proteins must be released in specific areas of the scaffold in a specific order. To accomplish this, the proteins are encapsulated in two types of slow-dissolving polymeric microspheres, first releasing CTGF and then TGF?3. Lastly, the protein-infused scaffold is inserted into the knee. The release says that in sheep, the meniscus regenerates in about 4 to 6 weeks. Eventually, the scaffold dissolves and is eliminated by the body.

The process was tested in 11 sheep. The animals were randomized to have part of their knee meniscus replaced with a protein-infused 3D scaffold (designated as the treatment group) or a 3D scaffold without protein (designated the nontreatment group). Following 3 months, treated animals were walking normally. The researchers report in postmortem analysis that the regenerated meniscus in the treatment group had structural and mechanical properties very similar to those of natural meniscus. The researchers are now conducting studies to determine whether the regenerated issue is long-lasting, the release says.

[Source:  Columbia University Medical Center]