A group of researchers
at Purdue University have discovered a new
way to repair damaged nerve fibers in spinal cord injuries. The
researchers are using nano-spheres injected into the blood shortly
after the accident to repair the nerve fibers. The nano-spheres are
synthetic copolymer micelles.
These spheres are used for drug
delivery and are about 60nm in size making them about 100 times
smaller than the diameter of a red blood cell. The spheres are being
studied as a method to deliver drugs to targeted cells in the body,
like cancer cells. The Purdue researchers have demonstrated that the
micelles themselves can repair damaged axons. Axons are nerve fibers
in the body that transmit electrical impulses to the spinal
"That was a very surprising discovery," said
Ji-Xin Cheng, an professor in the Weldon School of Biomedical
Engineering and Department of Chemistry. "Micelles have been
used for 30 years as drug-delivery vehicles in research, but no one
has ever used them directly as a medicine."
One of the
features of these micelles is that they combine two types of
polymers. One of the polymers is hydrophobic and the other is
hydrophilic (water hating and water loving). The hydrophobic polymer
can be loaded with drugs to treat disease.
In the Purdue
research, the micelles are used instead of conventional membrane
sealing agents. The outside of the micelles can be coated with poly
ethylene glycol (PEG) and with the coating they are not quickly
filtered by the kidney or captured by the liver. That gives the
micelles enough time to reach the site of tissue and nerve damage
inside the body. The researchers say that the micelles coated with
PEG can be used in non-toxic concentrations.
micelles, you need only about 1/100,000th the concentration of
regular polyethylene glycol," Cheng said.
Purdue have been using PEG to treat spinal cord injuries in animals
and have shown that PEG targets damaged cells and seals the damaged
area thereby reducing further damage. The PEG also helps to restore
During testing the researchers found that
treatment with PEG without using micelles was able to restore about
18% of axons in a segment of damaged spinal cord. When treated with
PEG infused micelles 60% of the axons in the damaged area recovered.
Micelle treated animals recovered the coordinated use of all four
limbs while those treated without micelles did not.
experiment mimics what happens in a traumatic spinal cord injury and
the findings have shown that the treatment with micelles could be
used to repair damage caused to the spinal cord from compression
injuries. The research is funded by a grant from Showalter Trust from
Purdue and a grant from the Indiana Spinal Cord and Brain Injury