Good Things Come In Small Packages

November 20, 2006 - I thought I would write about nanotechnology and brain tissue repair this month with a focus on a recently published paper from the Massachusetts Institute of Technology (MIT)1. The paper reports on the repair of severed optic nerves in animals, hamsters to be specific and was first reported in Conquer Chiari in the April 2006 edition. The question is can this technology hold promise for repairing brain tissue damaged from the compressive forces associated with Chiari?

Before answering this question, let me provide some background. First, what is nanotechnology? Nano is a prefix that means one-billionth. For example, one billion nanoseconds equal one second. Applied to length, a nanometer is one-billionth of a meter. A human hair is about 10,000 nanometers wide. Nanotechnology is technology on an extremely small scale. In electronics, nanotechnology might mean circuits that are so small they can only be seen with a powerful electron microscope. Such circuits may be so small that they approach the size of individual molecules. In engineering, nanotechnology conjures up images of super small machines, machines the size of a single cell or smaller with highly advanced functions.

In chemistry and biochemistry, nanotechnology often refers to molecules that are highly ordered in their structure and possess unique properties or functions as a result. It can also refer to molecules with the potential for self-assembly.

Recently, researchers at MIT utilized a unique molecule that can self-assemble into a fibrous network within damaged sections or areas of nervous tissue to "allow" repair and healing. The molecule is made from common amino acids which are the building blocks of proteins. The molecule is known as SAPNS. The SAPNS building block is very small. Its length is 5 nanometers and its width, 1.3 nanometers. It would take 2,000 of these building blocks attached end to end to stretch across the width of a human hair.

These SAPNS building blocks can hook together on their own to form a fibrous network with unique properties. The fibrous network formed by SAPNS self assembly acts as a scaffold to tie damaged nervous tissue together in such a way as to permit axonal regeneration without provoking an immune response or the formation of scar tissue.

The researchers at MIT severed the optic nerve of several hamsters. In one group of hamsters, SAPNS was injected into the severed nerve and the other group, saline was injected as a control. The results were nothing short of remarkable. Hamsters treated with SAPNS showed healing that was so complete it almost appeared as normal whereas no healing of tissue was observed in the control animals. Behavioral testing (orienting towards a small object) was also conducted in the hamsters to determine if actual vision was restored. 75% of the SAPNS treated animals showed a return in visual ability while hamsters in the control group demonstrated behavior consistent with blind animals.

Finally, the investigators looked at the metabolic fate of SAPNS and found that it was broken down to L-amino acids which were either used by surrounding tissue in the healing process or excreted in the urine.

Without a doubt SAPNS has great potential as a safe and effective treatment for axonal repair. However, there are different types of nerve tissue damage and several barriers to regeneration. Nerve tissue can be cleanly severed but it can also be crushed. Also, prolonged damage may be covered over with scar tissue. The barriers to regeneration include 1) scar tissue as just mentioned, 2) gaps in nerve tissue formed during resorption of dying cells after injury, 3) factors that inhibit axon growth in mature animals, and 4) failure of many adult neurons to initiate axonal extension.

The MIT experiment with SAPNS appears to overcome the first two barriers. SAPNS' effectiveness against the last two barriers is less clear. The damage caused by the compressive forces associated with Chiari is unlike that in the MIT experiment. Nerve tissue is not cleanly severed in Chiari. The damage can not be readily detected. While some very sophisticated imaging techniques can locate areas of the brain responsible for processing certain tasks, it can't locate precisely where damage may reside in specific individuals. Even if the damaged tissue could be precisely located getting SAPNS to the damaged tissue without disrupting healthy tissue represents a formidable task which brings me back to the picture above. Nanobiochemical technology may require an assist from nanoengineering technology. Some sort of nano-size device that can navigate through the body at the cellular level to locate damage and deliver a treatment agent such as SAPNS just might be able to do the trick. I guess we can all dream but dreams often come true. When my father was a boy in the 1920's, the notion of going to the moon was a distant dream. Just ten years ago, an agent to regenerate a severed optic nerve in hamsters was a distant dream.

The dreams and more importantly, the hard work of these MIT researchers is to be highly commended. These are the true heroes of healing deserving of our respect. After all, I am not aware of a single Reiki master who has restored vision in a hamster with surgically severed optic nerves.

1Rutledge G, Ellis, Yu-Xiang Liang, Si-Wei You, David K. C. Tay, Shuguang Zhang, Kwok-Fai So, and Gerald E. Schneider: PNAS 2006;103:5054-5059.

Ed. Note: The opinions expressed above are solely those of the author. They do not represent the opinions of the editor, publisher, or this publication. Mr. D'Alonzo is not a medical doctor and does not give medical advice. Anyone with a medical problem is strongly encouraged to seek professional medical care.