October 2, 2008: Purdue U. researchers have developed a method of using nanoparticles to deliver treatments to injured brain and spinal cord cells.
A team led by Richard Borgens of the School of Veterinary Medicine’s Center for Paralysis Research and Welden School of Biomedical Engineering coated silica nanoparticles with a polymer to target and repair injured guinea pig spinal cords. That research is being published in the October edition of the journal Small.
The team used the coated nanoparticles to deliver both polymer and hydralazine to cells with secondary damage from a naturally produced toxin. That research was published in August by the journal Nanomedicine.
Borgens’ group had previously shown benefits of the polymer polyethylene glycol, or PEG, to treat rats with brain injuries and dogs with spinal cord injuries. PEG specifically targets damaged cells and seals the injured area, reducing further damage. It also helps restore cell function, Borgens said.
“These particles are so tiny they can’t be seen with a regular microscope. They are about the size of a large virus. So you can inject as many as you need,” he said, adding that “they are safe inside bodies.”
In the first study, the researchers coated the nanoparticles with PEG to treat guinea pig spinal cord injuries. The treated spinal cord cells showed improved physiological functioning.
In the second study, the researchers added both PEG and hydralazine, an antihypertension drug, to mesoporous silica nanoparticles. These nanoparticles have pores that can hold the drug, which is later delivered to the damaged cells. The hydralazine was added to fight off secondary damage to cells that occurs after the initial injury.
“When cells are injured, they produce natural toxins,” Borgens said. “Acrolein is the most poisonous of these toxins. It’s an industrial hazard for which hydralazine is an antidote.”
Borgens and his team introduced acrolein into cells and then treated the cells with different combinations of hydralazine and/or PEG delivered by the mesoporous silica nanoparticles. They found that the treatment restored disrupted cell function caused by acrolein.
The team concluded that the use of nanoparticles to deliver both PEG and hydralazine increased the effectiveness of earlier PEG-only treatment by controlling and concentrating release of the drug and the polymer, producing a dual treatment and prolonging the treatment’s duration.
The goal of Borgens’ research is to improve the quality of life of those who have suffered head or spinal cord injuries. “All ambulances should have PEG on board,” he said. “It can probably save thousands of people from more severe head and spinal damage.”
The researchers now are testing the PEG/hydralazine treatment on rats with brain injuries. By the end of the year, they hope to test the treatment on naturally injured paraplegic dogs.
Financial support for the studies came from the state of Indiana and an endowment from Mari Hulman George.