New nanoscopic material that promotes cartilage growth

Researchers at the Northwestern University are first to invent a bioactive nanomaterial that promotes new cartilage to grow in vivo without using costly growth factors. The therapy is minimally invasive and activates the stem cells in the bone marrow producing natural cartilage. There is no conventional therapy that can do this so far. The results of this study are being published online on the February 1st edition of Proceedings of the National Academy of Sciences (PNAS); the paper is titled "Supramolecular Design of Self-assembling Nanofibers for Cartilage Regeneration".

Samuel I. Stupp, senior author of this study, Board of Trustees Professor of Chemistry, Materials Science and Engineering and Medicine, and director of the Institute for BioNanotechnology in Medicine said that because cartilage does not grow back, like bone does, strategies that can regenerate the tissue are of much interest. This is especially true for the countless people that end up at the orthopaedic surgeon's table to fix their bad knees, elbows and shoulders.

In adults, cartilage does not regenerate, explains Ramille N. Shah, first author and assistant professor of materials science and engineering at the McCormick School of Engineering and Applied Science and assistant professor of ortho[aedic surgery at the Feinberg School of Medicine. Once a person is fully grown they have all the cartilage they will have in life, she adds. Shah is also a resident faculty member at the Institute for BioNanotechnology in Medicine.

The nanoscopic material fibers stimulate stem cells that are in the bone marrow to make cartilage with type II collagen, repairing the damaged joint, said Shah. Currently there is a procedure called microfracture, which is the most commonly used by doctors right now. But this technique produces cartilage with predominantly type I collagen, which resembles scar tissue, shah added.

In animal testing, Shah together with a sports medicine orthopaedic surgeon and a team of researchers found that their technique produced substantially better results than the microfracture procedure alone. They also found that adding the expensive growth factor was not necessary to get the best results. Because of the gel material's molecular design, enough growth factor is already present in the body to regenerate cartilage.

To produce cartilage growth, the matrix only needed to be present for a month. In addition, because the matrix is based on self-assembling molecules, or peptide amphiphiles, they biodegrade into nutrients and replaced by natural cartilage.

The research was supported by The National Institutes of Health and the company Nanotope.