Nerve Cells Get A New Scaffold To Rely Upon: Coiled Conduit Design

There are people all around the world who owe their second life to prosthetic limbs after they have lost their arm or leg in some or the other way. Having a prosthetic limb not only gives them a substitute for the lost body part but also a sense of independence. There have been innumerable examples in various fields including sports where people have done feats which no one believed they could do after getting a prosthetic limb. The prosthetic arm or leg brings back the sense of self reliance and hence lead to a better life to some extent. The development of prosthetic limb is not new. A mummy fitted with a crude fake wooden toe testifies the fact.

#-Link-Snipped-#Researchers at Georgia Institute of Technology have developed a technology which strives to build a better communication between the nerve cells and the artificial electrodes in the prosthetic part. In prosthetic limb, where communication exists between the nerve cell’s ganglion and the electrodes present in the artificial limb, the connection between the two has to be carefully designed and developed. The nerve cells and the electrodes interact in form of electrical signals. If the nerve cells accept the foreign part and get fused with the electrode easily, even two way communication is possible. Ravi Bellamkonda and his teammates at Georgia tech have built a coiled conduit shaped structure which acts as base on which the nerve cells can grow. The base or scaffold is like a corrugated sheet rolled into a cylinder. The structure then acts both as a support and electrode path. The porous structure gets close to the end points of the nerves from where it can get and give signals. This revolutionary design was presented before Society for Biomaterials at a conference in early April.

The earlier designs included the fitting of flat metal disks with holes. They were called as sieve electrodes and had holes in them. The holes guided the severed nerves to grow and interlock with the artificial electrodes. The problem faced in this design was the growth of nerve cells through the holes was erratic and control over it was extremely difficult. Hence the design was modified and the design which is in vogue has foam supports for the nerves. Also, there are Nano fibers directing the path for nerves to grow. The design by Bellamkonda at Georgia tech is further modification to the present scaffold designs.

A base consisting of coat of polydimethyl siloxane is put on a glass slide to make it uniform. Then, another layer of SU-8, a light sensitive polymer is added. Corrugations are formed when SU-8 is exposed to UV light. The parts which are left unbounded are washed and what we get is an array consisting of rows upon conduit. The grooves are again coated with layer of base polymer. After this, the structure is rolled in a form of cylinder. The designs by Georgia Tech’s researchers are not equipped with electrodes but according to Dominique Durand, a professor of biomedical engineering at Case Western Reserve University, the problem could be solved in future. What is more important is the scaffold design. It is expected to be tested in a rat model and everyone is keeping their fingers crossed.

Another interesting aspect of this development is the use of biologically safe materials which show invitro growth without any complications.

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