by James Cavuoto, editor
September 21, 2009
September 21, 2009 |
A number of research institutions and commercial firms are pursuing new technology for peripheral nerve repair. The new findings may have an impact on the nerve repair market and lead to new treatments for neurodegenerative diseases such as multiple sclerosis.
After an injury that severs a peripheral nerve, such as one in a finger, nerve endings continue to grow. But to regain control of the nerve surgeons must join the two fragments. For large gaps surgeons used to attempt a more difficult nerve graft. Current surgical practice is to attach tiny tubes, called nerve guides, that channel the two fragments toward each other.
Today’s commercial nerve guides are made from collagen, a structural protein derived from animal cells. But collagen is expensive, the protein tends to trigger an immune response and the material is weak in wet environments, such as those inside the body.
Miqin Zhang, a University of Washington professor, recently authored a paper in Advanced Materials describing a new mixed-fiber material for nerve repair. The first component of their material, polycaprolactone, is a strong, flexible, biodegradable polyester commonly used in sutures. The second component, chitosan, is found in the shells of crustaceans. UW researchers combined the fibers by first using a technique called electrospinning to draw the materials into nanometer-scale fibers, and then weaving the fibers together. The resulting material has a texture similar to that of the nanosized fibers of the connective tissue that surrounds human cells.
Researchers at the University of Pittsburgh recently used biodegradable nerve guides to transplant adipose precursor cells into the injured peripheral nerves of laboratory rats to determine if the guided fat cells could improve nerve regeneration and functional recovery. APCs have demonstrated an ability to differentiate in vitro into cartilage (chondrogenic), bone (osteogenic), fat (adipogenic), and muscle (myogenic) cell types.
Control groups for this study included those with no treatment, those receiving an autograft but no nerve guide tube, and those receiving an autograft and nerve guide tube but no APC transplant in the guide tube. Their results also showed that transplanted human-derived APCs survived for up to 12 weeks in the injured peripheral nerve and formed a more robust nerve with nerve cells more than double the size of those formed using the conduit alone.
Several commercial firms offer products for the peripheral nerve repair market. Stryker Corp. offers a range of treatment options for peripheral nerve injuries, including NeuroMatrix, a resorbable, semi-permeable, collagen tubular matrix designed to create a protective environment for axonal growth across a nerve gap, and Neuroflex, a flexible conduit. Integra Neurosciences offers the NeuraGen nerve guide.
AxoGen’s Avance product is decellularized and cleansed extracellular matrix from donated human peripheral nerve. The cleaning process preserves the structural characteristics of the extracellular matrix needed to provide a bridge for nerve discontinuities while cleansing out the tissue’s irrelevant characteristics.
