Crab shells help spinal injury?

Material from crushed up crab and shrimp shells can restore electrical function to damaged guinea pig spinal cords, suggesting it may one day serve as a treatment for spinal cord injuries, according to a study published April 16th in the Journal of Experimental Biology. This paper is an "intriguing first step," said linkurl:Scott Whittemore,;http://louisville.edu/kscirc/bios/dr-scott-r-whittemore.html professor of neurological surgery at the University of Louisville, who was not involved in this research. But there are many steps that need to be taken first, he cautioned. "There needs to be more research and data presented before this is applied in a clinical setting," he added.Image: Wikimedia commons, Alex Trauma to the spinal cord often results in the deterioration of cell membranes, which then results in cell and tissue death, often leading to paralysis. One way to help eliminate loss of body functions is to seal the deteriorating cell membranes, researchers suggest. Chitin -- the main component of crustacean exoskeletons and fungi cell walls, previously used to build scaffolding for tissue growth -- has recently been suggested to stimulate spinal cord regeneration in rats. To see if chitosan, a form of chitin, could help seal cell membranes after spinal cord injury, neuroscientist linkurl:Youngnam Cho;http://www.vet.purdue.edu/cpr/who_we_are.html of the Center for Paralysis Research at Purdue University and her colleagues examined the spinal cords of guinea pigs. After dissection, the researchers soaked a sample of the injured spinal cord fragments in chitosan, and then looked for leakage of lactate dehydrogenase (LDH) -- an intracellular enzyme that is found in cerebrospinal fluid -- to see if the cell membrane was intact. Surprisingly, the researchers detected only low levels of LDH release from the chitosan-treated cells -- even lower than those treated with polyethylene glycol (PEG), a "well-known cell membrane sealant," Cho said -- suggesting that the cells had been fused and sealed. The researchers also tested the treatments in vivo, examining spinal cord recovery in the guinea pigs after causing a compression injury to the middle region of the spinal cord. Following the injury, all animals lost nerve signaling from the tibial nerve -- a sensory nerve in the hind limb -- confirming the damage to the spinal cord. But when treated with a subcutaneous injection of chitosan, all eight animals recovered tibial sensory activity in their hind limb, indicating that the treatment had successfully repaired the disrupted membrane. Cho speculated that the chitosan is able to penetrate the injured cell membranes, where it interacts with the disorganized phospholipids, somehow repairing the membrane. The exact details of this mechanism, however, remain unclear, linkurl:Patrick Carr,;http://www.med.und.edu/depts/anatomy/carr.html a neuroscientist at the School of Medicine and Health Sciences, University of North Dakota, said in an email to The Scientist. He added that the mechanisms will require additional work to "extract the subtle nuances" of chitosan's action. More research is also required, Whittemore said, to "fully evaluate the approach" in other contexts. First on Cho's list of follow-up experiments is to determine if chitosan will have the same effect on the cutaneous trunchi muscle reflex -- a motor pathway widely used to test for functional recovery after nerve damage. In the current study, the researchers only looked at "a sensory pathway," Carr said, and they "must be careful not to over-interpret the sensory findings, as they do not indicate the level of motor recovery," and therefore the possibility of paralysis recovery. Additionally, spinal cord research has historically focused on rats as the dominant model system, raising the question of whether the guinea pig results will translate to other species. Because guinea pig spinal cords are easier to extract than rat spinal cords, they are an ideal first step in spinal cord research, Cho said, but the next steps will include testing the treatment in rats and eventually dogs before it is even considered for humans. Still, this paper raises a lot of interesting questions, Carr said. "From this work, scientists must now dig into this issue with gusto" to see how chitosan is working and how broadly the treatment may be applied. "Ultimately," Cho hopes, "we will observe the potential of chitosan to be capable of restoring the integrity of the neuronal membranes after mechanical brain damage." Y. Cho et al., "Chitosan produces potent neuroprotection and physiological recovery following spinal injury," The Journal of Experimental Biology, published online April 16, 2010, doi:10.1242/jeb.035162. **__Related stories:__***linkurl:Sizing up nanoparticles;http://www.the-scientist.com/article/display/57245/ [1st April 2010]*linkurl:Plugging up the injured spinal cord;http://www.the-scientist.com/article/display/12753/ [10th December 2001]*linkurl:Food dye lessens spinal injuries;http://www.the-scientist.com/blog/display/55865/ [27th July 2009]

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