Jump to content
RemedySpot.com

How injured nerves grow themselves back

Rate this topic


Guest guest

Recommended Posts

How injured nerves grow themselves back

http://www.eurekalert.org/pub_releases/2010-09/cp-hin092710.php

Unlike nerves of the spinal cord, the peripheral nerves that connect our limbs

and organs to the central nervous system have an astonishing ability to

regenerate themselves after injury. Now, a new report in the October 1st issue

of Cell, a Cell Press publication, offers new insight into how that healing

process works.

" We know a lot about how various cell types differentiate during development,

but after a serious injury like an amputation, nerves must re-grow, " said

Lloyd of University College London. " They need a new mechanism to do

that because the developmental signals aren't there. "

That kind of regrowth isn't easy to pull off. Peripheral nerves are long cells;

their nucleus is in the spinal cord and the axons that extend from them and

relay nerve messages can reach all the way down a leg. " When a nerve gets cut,

all the axons downstream degenerate, " Lloyd said. Regrowth requires that the two

ends somehow find their way back to each other through damaged tissue.

Scientists knew that Schwann cells were important to that process. Those cells

are found wrapped around axons, where under normal circumstances they are rather

" quiet " cells. All of that changes when an injury occurs; those Schwann cells

de-differentiate back to a stem-cell-like state and play an important role in

bridging the gap to repair damaged neurons.

" Schwann cells could sit on a nerve for years and then, at any point, switch

states, " Lloyd said. " They are quite unusual cells. " (There are other examples

of cells that can return to a stem-cell-like state, she said. For instance,

cells in the liver and the endothelial cells that line blood vessels.)

But, the new study shows, the Schwann cells need help to repair the nerves

properly. That help comes from a well-studied cell type known to play a role in

wound healing: fibroblasts.

" This is a new role for fibroblasts, " Lloyd said, an exciting find given that

the cells are the type that grows when you place animal tissue in cell culture

and have been very well studied as a result. " There is lots known about them,

and they are always present at wounds. This shows that they act in a completely

new way. "

The fibroblasts send a signal to the Schwann cells, causing them to sort

themselves into clumps, or cords, that make their way out of the nerve stump as

a group. Those cords guide the regrowth of axons across the wound. Lloyd's team

found that the response to the so-called ephrin-B signal issued by the

fibroblasts depends on a factor called Sox2, best known for its central role in

embryonic stem cells. Sox2 is also one of a handful of ingredients that can help

reprogram adult cells to behave like embryonic stem cells.

Without the ephrin-B signal, Schwann cells fail to migrate in an organized

fashion and the axons don't grow back properly.

Lloyd said the new findings might lead to ways to improve the repair of

peripheral nerves, noting that the natural process isn't all that efficient.

" It's not perfect, but if a hand is cut off and sewn back on, you can get some

movement, " Lloyd said. Her team is actively exploring ways to improve upon the

natural nerve-healing mechanism now.

The researchers also have plans to investigate whether similar mechanisms might

be involved in the movement and spread of cancers of the peripheral nervous

system. " We don't know yet, but it wouldn't be surprising if this is relevant to

the movement of other cells, " Lloyd said.

###

The researchers include Simona Parrinello, MRC Laboratory for Molecular Cell

Biology and the UCL Cancer Institute, University College London, London, UK;

Ilaria Napoli, MRC Laboratory for Molecular Cell Biology and the UCL Cancer

Institute, University College London, London, UK; Sara Ribeiro, MRC Laboratory

for Molecular Cell Biology and the UCL Cancer Institute, University College

London, London, UK; Wingfield Digby, MRC Laboratory for Molecular Cell

Biology and the UCL Cancer Institute, University College London, London, UK;

Marina Fedorova, MRC Laboratory for Molecular Cell Biology and the UCL Cancer

Institute, University College London, London, UK; B. Parkinson, University

of Plymouth, Plymouth, UK; Robin D.S. Doddrell, University of Plymouth,

Plymouth, UK; Masanori Nakayama, University of Munster, Munster, Germany; Ralf

H. , University of Munster, Munster, Germany; and Alison C. Lloyd, MRC

Laboratory for Molecular Cell Biology and the UCL Cancer Institute, University

College London, London, UK.

Link to comment
Share on other sites

Join the conversation

You are posting as a guest. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...