A widely criticized experiment last year saw a Chinese researcher remove a gene in twin girls on the embryonic stage in an attempt to protect them from HIV. A new study suggests that using a drug to remove the same gene in people with stroke or traumatic brain damage can help improve their recovery.
The new work shows gene removal benefits in stroke-forced mice by drug use, approved as an HIV treatment. It also focuses on a sample of people who are naturally born without a gene. People with no genes get faster and more fully from stroke than the general population, researchers found.
Combined results suggest medication boost recovery to people after stroke or traumatic brain damage, says S. Thomas Carmichael, senior researcher of study and a neurologist at the University of California, Los Angeles , David Geffen School of Medicine. His team started a follow-up human study to test drug effectiveness.
The combination of mouse research and the use of human genetic data to confirm the relevance of drug targets makes new research a "landmark paper," says Jin- Moo Lee, co-director of Barnes -Jewish Hospital at Washington University Stroke and Cerebrovascular Center in Saint Louis who are out of work.
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Carmichael and others spent years looking for genes and other biological pathways that could lead to medications to help repair the brain itself after a stroke or brain injury. CCR5 is the first candidate to show real promise, some experts say. For stroke and traumatic brain injury patients, "I believe this is the beginning of hope," says Alcino Silva, a neuroscientist at U.C.L.A. who worked with Carmichael in the new study. The results were published this week at Cell .
The drug used to block the activity of CCR5 was on the market since 2007 and was approved as a treatment to slow the progression of HIV and AIDS. Carmichael gave the drug, called maraviroc, to stroke-induced mice. The loss of gene activity in brain motor neurons has "had a tremendous impact on recovery," he said. Drugs are not easy to cross the blood-brain barrier but have done enough to maintain brain connections involved in chemical signaling and increasing connections between regions of the brain, the study showed .
For human-study analysis-the study examined 68 individuals without CCR5 genes, including 446 controls. Those who suffered from stroke-and also had a natural gene removal-recovered movement abilities more quickly and had less cognitive deficit months after stroke than patients with full CCR5 . The exact mechanism behind the result is unknown. To a healthy person, the gene CCR5 was thought to promote learning and memory by acting as a "stop" signal, telling neurons to receive only one memory and hold it , instead of continuing to receive and keep every signal coming in, says Carmichael. Immediately after a stroke or brain injury the gene helps to reduce the excitability of the neurons, which helps limit the damage, he says. But if the gene persists in pumping out "stop" signs, it also affects the brain's ability to develop new connections and damage repairs, he added.
Carmichael's method will turn off these signals by starting people with medication about five to seven days after stroke and continuing about three months, allowing the brain to have more great opportunity to recover. At present clinical trial participants also undergo intensive physical therapy to restore the movement. These two treatment strategies are important, says Steven Cramer, a stroke recovery expert at the University of California, Irvine, who did not participate in research. Drug treatment can open the door for reorganizing circuits in the brain, but individual recovery efforts-such as studying the activity in the first place-must also be noted. "Because you'll throw a magic pixie dust into the brain, you do not mean to fix the problem," he said. "You must pair them with training experience."
Cramer claims that anti-1945 treatment CCR5 can be "one of the main pillars" of therapeutic advances in stroke recovery