Mind Bender

Perspectives: Research and Creative Activities at SIUC, Fall 2007

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MIND BENDER

How do you mend a broken brain? Neuroscientist Michael Hoane and his team of undergraduate and graduate students have made it their mission to find out.

Literally and figuratively, traumatic brain injury is a killer. Each year in the United States it causes about 50,000 deaths, results in a quarter of a million hospitalizations, and permanently disables 80,000 to 90,000 survivors.

It's also a risk factor for depression, Parkinson's disease, and Alzheimer's disease. And it's become an even more pressing problem because thousands of Iraq War veterans are returning with often-undiagnosed brain injuries from explosions and accidents.

Yet doctors have few tools to fight TBI. Medical intervention focuses on reducing swelling of the brain in the days after injury to save lives and limit damage.

"TBI survivors have permanent disabilities—motor, sensory, cognitive, affective [emotional]," says Michael Hoane, an assistant professor of psychology who heads SIUC's Restorative Neuroscience Lab. "It's a socially and economically debilitating condition, and all potential treatments for it have failed in Phase III clinical trials" (the final stage of testing before a drug can be approved by the FDA).

When a person takes a punishing blow to the head, the trauma sets off a cascade of biochemical effects—swelling, inflammation, oxygen deprivation in the brain, and eventually neuron death—that can lead to short- or long-term impairment. The time course of this cascade varies, but the die is cast within a week or two of the injury. Beyond that, little can be done medically, although rehabilitation facilities can help disabled patients function better.

In fall 2001 Perspectives reported on research to improve learning and memory in TBI survivors by using a small implant that delivers mild electrical impulses to the body's vagus nerve (www.siu.edu/~perspect/01_fall/vagus.html). Hoane is pursuing another avenue: testing substances that might be able to prevent, reduce, or repair the post-injury flood of damage. He thinks that something as simple and inexpensive as mega-vitamin "cocktails," if given within a few hours of the injury, could change the outlook for TBI patients.

Hoane's lab team induces brain injuries in anesthetized rats, either unilaterally (on one side of the cortex) or bilaterally (like the frontal injuries so often caused by car accidents). Then they try to minimize or repair the resulting damage, restoring lost function to the injured animal. The information they're gaining will be critical to designing eventual clinical trials in humans.

One of the most promising substances they've tested is nicotinamide, a form of vitamin B3. Given in massive amounts shortly after an injury, it seems to protect the brain from damage.

"With different types and severities of brain injury, animals treated with B3 are no different from controls on many measures," Hoane says. "The first time I saw those effects, I didn't believe them." But repeated trials convinced him.

Hoane's team has many ways to assess injury and recovery. Physiological measures look at changes in the brain: the size of the lesion caused by the injury, the extent of swelling and cell death, the amount of inflammation. "B3 has strong effects on all these pathophysiological markers," Hoane says. In rats injected with B3, "the lesions are smaller, sometimes hardly observable" when compared to those of injured rats given a saline (placebo) injection.

Behavioral tests measure changes in function. In rats as in humans, an injury to one side of the brain causes motor problems on the opposite side of the body. When you hold a rat up to a table edge and tickle its whiskers, for instance, it normally will place its forelimbs on the table—but a rat injured on the left side of the brain can't do that with its right forelimb. Likewise, a normal rat placed in a glass tank will rear up and use both forepaws to explore the sides of the enclosure; an injured rat won't use the afflicted forepaw.

If a high dose of B3 is given to the animal shortly after it's injured, however, it will act like a normal rat on both of these measures.

Other TBI impairments include sensory deficits. Some TBI patients will pay less attention to one side of their body or even lose awareness of it, for example. This "sensory neglect" is studied in rats with a simple test that involves putting adhesive dots on a rat's forelimbs and seeing whether he pulls them off with his teeth.

"Rats are naturally clean, just like cats; they don't like things on their fur," Hoane explains. A rat with a left-brain injury may ignore dots placed on his right forelimb, but after treatment with B3, he'll once again be able to notice and remove those annoying stickies.

Other tests, such as negotiating a water maze, gauge the animal's ability to form new memories. B3 improves injured rats' performance on this test as well, though to a lesser degree.

Despite these hopeful indicators, Hoane cautions, "Whether [B3 therapy] will translate to humans is hard to say."

Before coming to SIUC three years ago, as a professor at East Carolina University, he and his students found that giving magnesium to brain-injured rats facilitated recovery. Physicians at the University of Washington later ran clinical trials with TBI patients based on these data. "An early study found some reduction in mortality," Hoane says, "but a later, larger study found no benefit. It was very disheartening."

Part of his research at SIUC, he says, involves "how best to test these compounds. How can we make the animal models more representative of what we might see in humans?"

For instance, whereas most of the lab's research has been done using young male rats, graduate student Alicia Swan is now testing middle-aged rats. ("They show an age-related vulnerability," Hoane says.) The team plans to run tests with female rats too.

One of the most important things they're doing is to give B3 at different times post-injury. In their initial, proof-of-principle studies, they administered the vitamin only 15 minutes post-injury. That's an ideal scenario, one that would seldom be possible for injury victims in the real world.

"Now we test giving B3 six, eight, 24 hours after injury and try to optimize those treatments," Hoane says. Promisingly, B3 "still has very strong effects, even given in a low dose at late onset."

The University of Washington team, which hopes to test B3 in TBI patients, is working closely with Hoane to determine the type of lab data that will be most useful to them. "Those conversations have helped us a lot (in planning experiments)," Hoane says. "One of the things that's of great interest to them is how the presence of alcohol would interact with B3 treatment, since 40 to 50 percent of TBI patients have alcohol in their system when they arrive in the emergency room.

"We're also trying to figure out ways to test the animals to [assess] more human-like deficits [resulting from TBI]. A major one in humans is impulsivity. No one has studied that in rats. Also emotionality and depression. We try to test across the whole spectrum of behavior. We're even looking at anxiety in some studies."

Hoane's lab has tested two B3 dosages: 50 versus 500 milligrams per kilogram of body weight. The higher dose works better, but the differences aren't huge, Hoane says, and "most clinicians would prefer 50 milligrams per kilogram for humans."

brain sections from treated and untreated rats

His lab is now testing the 50 mg/kg dose in rats over a longer time period to see if that boosts effectiveness. And graduate student Andrea Goffus is treating rats with a time-release capsule that will continuously infuse B3. This is a particularly interesting study, Hoane says: "Most drugs have never been tested this way in animals."

The University of Washington team has an investigational new drug license from the Food and Drug Administration to test tolerance of the 50 mg/kg dose in people. Note, this is not a try-it-yourself treatment. The dose far exceeds the recommended daily intake; it is given by IV; and it requires a sterile, medical-grade formulation of vitamin and solution media. And of course no one knows yet if B3 will work in humans with TBI.

The Washington group has shown, however, that this dosage does cross the blood-brain barrier in humans—an important hurdle. "We think a lot of failed treatments [for TBI] have failed because they haven't crossed into the brain," Hoane says. Such pilot data are critical if the group is to win a grant for clinical trials.

Meanwhile, Hoane's lab has seen benefits from giving high doses of vitamin B2 to injured rats, and is testing B6 as well (undergraduate Nick Kuypers is running these studies). Jeremy Pierce, another undergraduate, explains that the lab is analyzing urine from injured rats to see what vitamins are being metabolized more—used more by the body—after brain injury. That could give clues as to which other vitamins might help recovery.

The team is guessing that a combination of nutrients may work better than any one alone. Since TBI involves multiple types of damage in the brain, says Hoane, "You may need a cocktail therapy."

Vitamins aren't the only substances Hoane's lab is testing. In a project funded by SIUC's undergraduate research program and by a company called Cognosci Inc., Pierce and fellow undergrads Nicholas Birky, Michael Holland, and Tan Dang got good results with a compound called COG1410, a snippet of a fat-transporting protein. Former graduate student Olga Kokiko showed that raloxifene, a drug that acts on estrogen receptors, may hold promise too.

And in other work done at East Carolina, Hoane found "immediate improvements" when he transplanted a certain type of neuron derived from mouse embryonic stem cells into rats one week after injury. This result was startling, he explains, because "it couldn't be due to cell replacement by the stem cells—it takes weeks for them to actually integrate with the body's tissue. We think it's due to some kind of growth factor or neuroprotective chemical that these cells are producing."

Although he'd like to continue research with stem cells if he can get funding, he remains most interested in vita-nutrient therapy. "It seems logical that if you're putting something in the body that it's used to using, it should be able to handle that in a crisis," he says. "There's a whole field of nutritional neuroscience, and I'm evolving in that direction."

Hoane's research has been funded by the National Institute of Neurological Disorders and Stroke—specifically, by a type of grant aimed at getting undergraduates involved with research. Since joining SIUC, Hoane has hired more than a dozen undergraduates to work with him and his graduate students. This fall, he has four upper-level undergraduates running their own projects, plus another four to five undergraduates at the beginning stages of lab work.

He believes that undergraduates can usually get more extensive research experience at SIUC than at bigger institutions.

"My senior undergraduates are working at the same level as graduate students," he says. "I put a lot of responsibility on their shoulders. You have to take the risk of giving them an important project to do. Mistakes happen, but we deal with that."

Hoane finds both the interaction and the research fun. "It comes naturally to me," he says. "As a small child I liked to take things apart and put them back together.

"We're [investigating] how to put the brain back together."

—by Marilyn Davis