Washington plays host to SfN 2011

Official SfN 2011 Header

It has been a whole year and once again the Society for Neuroscience annual meeting decends on another major US city - this time Washington , DC.

Each year I try to give a flavour of the meeting and write about some of the interesting things I see at the meeting. Washington at this time of year is looking pretty good; cold but sunny. Now the meeting has started in earnest, though, there will be little time to appreciate this as most of the day will be spent underground in the large Hall C where the exhibitors and scientists do there stuff.

Today we had two poster sessions devoted to spinal cord injury. Homework done, I headed off to take a look at a number of papers looking at the potential of various biomatrials in SCI. SCI causes many problems including neuronal cell death, damage to the axons that convey information up and down the cord from the brain to the body and back again, Glial scar formation as well as up-regulation of scar-like material in areas surrounding the injury site. This makes repair and regeneration of the spinal cord very difficult. Another important clinical consequence of SCI is often the formation of large (cystic) cavities. It is proposed that biocompatible materials may help to overcoming this and other problems associated with SCI. With biomaterials, for instance, it may be possible to create a scaffold structure through which regenerating nerves may grow. They may be able to bridge the cystic cavity which are otherwise no-go areas for regrowing axons.

They can have other properties which we might be able to utilise. There is no one biomaterial. Indeed, the term "biomaterials" really is just a generic description of a class of materials that are biocompatible. They are often polymers - chains of single units or groups of units that are strung together. The type of units that these polymers are made of dictates their properties. They may be naturally occuring or man-made. On top of that they may be stable and permanent or biodegradable. The science and use of biomaterials in many medical fields is advancing and there were certainly quite a few posters describing the effects of biomaterials in SCI today.

J. Hyun (presentation number #64.12) presented on a 3D glass fibre scaffold implanted into the gap created by the complete transection of the spinal cord. The glass fibre was created in such a way to incorporate collagen to act as a suitable base material over which regenerating axons could grow. They found improvements in locomotor function (as determined by the BBB scale).

The biomaterial described above was pre-formed before implantation but a number of investigators in this session have been examining materials that can be injected as liquids before turning into more solid structures within the tissue. T. Novosat (#64.13) described a “reverse thermal gel” which, simply put, is a material that undergoes a change in structure as the temperature changes. It is described as “reverse” because it is liquid at low temperatures but becomes gel-like at higher temperatures such as body temp. This property is particularly useful as it can be injected at a low temperature as a liquid, spread like a liquid and as its temperature increases within the tissue it becomes gel-like. One can imagine therefore it integrating into the tissue much better and offering a substrate on which axons and other cells can now regrow. The purpose of the study was to check the biocompatibility of the material which they reported as good, eliciting no obvious adverse effects.

L. Conova (#64.14) used a very similar concept but pre-mixed their liquid polymer with the neurotrophin BDNF (growth supporting molecule) and or fibroblast cells to look at the effect the biomaterial had on graft cell survival rates. As above, they did not report any adverse effects from the injected material and provided evidence that cells survived better when delivered in the biomaterial. The material also appeared permissive for axon growth when delivery included the neurotrophin BDNF.

Y. Liu (#64.15) from the Fehlings lab, used a novel small peptide that on injection self-assembles to form fibres “that resemble the native” cord microstructure. Injection of this material lead to dramatically less neuronal cell death, a reduction of Glial scarring and inflammation and a significant promotion of axonal preservation and regeneration. They also reported improvements in the quality of the electrical signal carried along axons and better functional outcomes.