Print 11 comment(s) - last by tmouse.. on Nov 10 at 3:10 PM

Micelles are commonly used in biomedicine to deliver drugs to tissue

Spinal cord injuries can be the most devastating of any type of injury sustained in an accident. The injuries can leave the victim paralyzed and can lead to death. Research into the treatment of spinal cord injuries is well funded and being undertaken around the world.

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 cord.

"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.

"With the micelles, you need only about 1/100,000th the concentration of regular polyethylene glycol," Cheng said.

Researchers at 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 cell function.

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.

The 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 Research Fund.

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By Visual on 11/10/2009 5:10:35 AM , Rating: 3
It is still unclear to me, are the micelles effective just by themselves, even without carrying PEG? Or do they simply make PEG more effective? The way I read things, different parts of the article seemed to imply a different answer on this question. Very confusing.

If the micelles are effective just by themselves, this seems like a totally random discovery to me, and I wonder if it is understood and explained at all.

RE: random
By tmouse on 11/10/2009 9:18:28 AM , Rating: 3
They use PEG–polyester micelles. Its the PEG that "heals" the damaged membranes. PEG unimers are rapidly cleared whereas the micelles are not. The micelles are composed of PEG. It sees to be more effective than just injecting or IV 30% PEG.

RE: random
By bentheman939 on 11/10/2009 11:32:06 AM , Rating: 3
I completely agree about the random part. I'm a biomedical engineer, and PEG/PEO are used all the time in copolymers or to treat surfaces. It "masks" these surfaces from the immune system, making whatever you are implanting much less immunogenic. I have personally made many formulations of micelles using PEG. I have no idea how this common biomaterial on its own is doing anything therapeutic to nerve cells.

If it is... boy would the field of biomedical engineering feel stupid. We've been using this stuff every day for 50 years!

RE: random
By tmouse on 11/10/2009 3:10:53 PM , Rating: 3
It does have effects helping to reestablish the membrane integrity shortly after damage. The alterations in calcium transfer by the damaged membranes and the establishment of free radical cascades often cause additional damage leading to more neural apoptosis. Current therapies include IV 30% PEG or local injections, but systemic clearance results in minimal improvement, but any decrease in damage is a bonus to the patient. Interesting read, it's in the current advanced publication section of Nature nanotechnology

can this technique...
By MrPoletski on 11/10/2009 3:58:58 AM , Rating: 3
be adapted?

Yes, fixing spinal cords is awesome, but I wonder if it can be applied to more general nerve injuries... i.e. actual brian injuries and damage.

Maybe it could fix cereberal palsy? I have a friend who would be very happy if it could in the future...

RE: can this technique...
By tmouse on 11/10/2009 9:29:01 AM , Rating: 2
I cannot say it will not help but it does not restore dead nerve bodies. It's similar to patching a tire that has a hole, after the tire is shredded the patch will not restore the tire. If the condition (and there are many) that causes the CP is treated at the same time it could limit the extent, but that just speculation. Think of PEG as a compound that makes the membrane more fluid so the hole fills in. Some form of neural regeneration would be required to help most CP patients. Believe me it is being worked on.

How long till Grey Goo?
By Bateluer on 11/9/2009 4:55:19 PM , Rating: 1
1 year? 5 years? 10 years?

RE: How long till Grey Goo?
By MozeeToby on 11/9/2009 5:15:04 PM , Rating: 2
Kurzweil had a great article a while back about Grey Goo and how it isn't a significant issue. The basic argument boils down to the fact that it always takes more energy and time to rip something apart and re-arrange it's pieces the way you want them then it does to just rip something apart. In other words, replicators will always be vulnerable to nano-machines created in a controlled manufacturing environment.

If it is a problem it all, it will be on par with fires, and indeed that is the solution that Kurzweil invisioned; having stocks of nano-phages at fire stations, literally hosing the grey goo down with nano-phages.

If only
By trisct on 11/9/2009 4:33:46 PM , Rating: 2
Quick, someone call Christopher Reeve...

By R6Raven on 11/9/09, Rating: 0
RE: Alternative?
By Camikazi on 11/10/2009 10:49:01 AM , Rating: 2
Only problem is, like Ron White said, "You can't fix stupid". They will just ignore and kill off those new brain cells :/

"The whole principle [of censorship] is wrong. It's like demanding that grown men live on skim milk because the baby can't have steak." -- Robert Heinlein

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