Paralysed mice walks again after gel is injected into spinal cord

A section of the spinal cord in a gel treated mouse, showing regenerated nerve fibers in red Samuel I.

Stupp a self assembling gel injected into the site of the spinal cord injury in paralyzed mice allowed them to walk again after four weeks.

The gel mimics the matrix normally found around cells, providing a scaffold that helps cells grow. It also provides signals that stimulate nerve regeneration.

Samuel Stupp of Northwestern University in Chicago and his colleagues created a material made up of protein units, called monomers, that self assemble into long chains, called supra molecular fibrils, in water.

When injected into the spinal cord of paralyzed mice in the hind legs, these fibrils formed a gel at the site of the injury.

The researchers injected 76 paralyzed mice with fibrils or a sham saline treatment a day after the initial injury.

They found that the gel allowed paralyzed mice to walk for four weeks after the injection, while the mic and placebo failed to regain the ability to walk.

The team found that the gel helped regenerate severed ends of neurons and reduced the amount of scar tissue at the injury site, which usually forms a barrier to regeneration.

The gel also improved the growth of blood vessels, which supplied more nutrients to the cells in the spinal cord.

“The extent of functional recovery and strong evidence for biological repair that we have seen using a model that truly emulates severe human damage makes therapy superior to other approaches,” says Stupp.

Other treatments use stem cells, genes or proteins and have questionable safety and effectiveness, says Stupp.

The walking ability of the mice was assessed in two ways. First, the mice were given an overall score to represent ankle movement, body stability, leg placement, and steps.

The gel-treated mice scored three times higher than the sham-treated mice.

The team also assessed walking ability by dipping the mice’s hind legs in colorful dyes and letting them walk on a narrow track lined with p and a whites.

This test showed that the gel increased both the width and the length of the strides.

“A higher stride length and width should be related to more regrown axons [nerve fibers] that innervate the muscles in the leg,” says Stupp.

The regenerative effect of the gel is due to the short protein sequences the team designed at the ends of the monomers.

These sequences provide regenerative signals that are picked up by receptors on the surface of cells in the spinal cord.

By modifying the non signal portion of these monomers, the team found that improving the ability of molecules to enter and exit the larger fibrillar structure improved recovery in mice, possibly because the increased movement allowed signals to interact with multiple receivers. on the cells.

“It would be very exciting if this finding could translate into humans, although the scale issues of murine therapies for humans are not insignificant,” says Ann Rajnicek of the University of Aberdeen in the UK .

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