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Brain knitting
Nature ^ | 4/13/2006 | Philip Ball

Posted on 04/18/2006 4:50:18 AM PDT by Neville72

Healing brain and spinal-cord injuries is one of the most desirable, but challenging, goals of regenerative medicine. Molecules that self-assemble into nanoscale filaments may show the way.

A scaffold of nanoscale fibres that self-assembles from small, synthetic protein-like components provides a framework for the regrowth of damaged brain tissue, allowing vision to be restored in hamsters with brain lesions, a team in the USA and China reports1.

Rutledge Ellis-Behnke of the Massachusetts Institute of Technology and his co-workers say their results show that nanotechnology is not just about microelectronics and tiny machinery, but has significant implications for biomedicine.

Rutledge Ellis-Behnke of the Massachusetts Institute of Technology and his co-workers say their results show that nanotechnology is not just about microelectronics and tiny machinery, but has significant implications for biomedicine.

Their nano-scaffold, being made of short peptides, is biodegradable and non-toxic, causes no immune response, is injectable — it self-assembles when the molecules come together in a salty solution — and, because it is composed of nanofibres, allows an intimate interaction between the peptide matrix and the surrounding tissue. The researchers say that it provides a 'permissive environment' that helps cells, such as neurons, regrow and knit together damaged tissue.

The scaffold is formed from peptides containing ionic amino-acids groups, designed so that they will come together spontaneously in -sheet structures like those found in proteins. Ellis-Behnke's colleague Shuguang Zhang of MIT has been designing such peptides for several years, tuning the peptide structures to make fibrous aggregates just a few nanometres thick that link up into three-dimensional networks with possible uses in tissue engineering2. Several years ago he and his co-workers reported that these scaffolds could support the growth of neuronal cells and the outgrowth of neurites (neuron filaments) in cell cultures3.

These promising results were echoed by those obtained by Samuel Stupp's group at Northwestern University in Illinois, who have found that a nanofibre network made from a different kind of self-assembling peptide, with an amphiphilic structure, can form around neuron progenitor cells in solution and trigger the sprouting of neurites4.

Both the MIT and Northwestern researchers hope that these self-assembling nanoscaffolds might help damaged brain or neural tissue to regenerate, for example after spinal-column injuries. Such damage is problematic not only because it can be particularly debilitating but because there are several obstacles to the regrowth of the neural conduits (axons). Adult axons don't tend to grow back spontaneously; instead, such lesions create scar tissue. That is another reason why Stupp's peptide scaffolds4, which suppressed the differentiation of neuron progenitor cells into scar-forming astrocytes, looked so appealing.

Ellis-Behnke and colleagues have now taken things a step further by demonstrating the regeneration of functional brain tissue in live animals. They made cuts in the part of the midbrain of hamsters that processes vision, rendering them sightless. In untreated animals, this lesion turned into scar tissue that prevented any regrowth, and the hamsters remained blind. But when Zhang's self-assembling peptides were injected into the wound region, the lesions healed within several weeks: the axons grew to close the gap, and the animals regained some sight. The peptide network, say the researchers, "appears to knit the tissue together".

They hope ultimately to conduct trials on humans who have suffered spinal-cord injuries.


TOPICS: Miscellaneous
KEYWORDS: biotechnology; brain; medicine; mit; nanotechnology; science
Rat hippocampal neurons grown on a self-assembling peptide nanofibre scaffold. Green portions show active synapses. Reprinted from ref. 3. Copyright (2000) National Academy of Sciences, USA.


1 posted on 04/18/2006 4:50:18 AM PDT by Neville72
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To: Neville72

Very cool!


2 posted on 04/18/2006 4:57:12 AM PDT by Woodstock
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To: Neville72

The cosmos is God's holy scripture. His truth is continuously revealed. Mankind's discoveries are God's revelations.


3 posted on 04/18/2006 5:14:50 AM PDT by Savage Beast ( The Spirit of Flight 93 is the Spirit of America. R.I.P., Todd Beamer.)
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