Na Duk-lyul
Professor in Department of Neurology, Sungkyunkwan University School of Medicine
Na Duk-lyul, a noted neurologist in Korea, published more than 250 articles on dementia and cognitive neuroscience in peer-reviewed, international journals. In 1995, the Alzheimer’s disease expert established a cognitive test, the Seoul Neuropsychological Screening Battery, which is now the most commonly used one in the country.
Despite the huge amount of money and effort that have gone into Alzheimer’s research, the disease remains incurable, and current treatments bring only temporary relief but cannot significantly slow its progression. Scientists still do not know how the disease develops in the first place. However, they do know now that one of the disease’s hallmarks is sticky protein clumps, or amyloid plaques, in the brain. The plaques and neurofibrillary tangles are prime suspects in damaging and killing nerve cells, which eventually creates voids in the brain. Thus, it is widely assumed that removing the plaques from the brain will alleviate symptoms of the disease such as memory loss and language impairment. Over the past two decades, scientists in collaboration with global pharmaceutical firms have been trying hard to develop drugs that can eliminate amyloid plaques from an affected brain, but have not yet been able to do so. Na Duk-lyul, a renowned neurologist at Samsung Medical Center, took a different approach to the issue. Since 2008, he has been working with Medipost, a Korea-based biotechnology company, to develop a drug using mesenchymal stem cells, which he believes can cure the disease without having to remove amyloid plaques. “After conducting experiments on mice and beagles, our team has found that human umbilical cord blood-derived mesenchymal stem cells can significantly reduce the level of amyloid plaques in the brain,” Na said in an interview. “We still don’t know much about how the stem cells work, but they certainly do.” After receiving approval from the Ministry of Food and Drug Safety in 2013, he began conducting phase 1 of the clinical trials for Neurostem, a novel therapeutic agent for Alzheimer’s disease.
“The results are expected to come out in a few years, and I’m confident that it will be a success,” he said. For many years, Na said the biggest challenge for him was to come up with an effective way of delivering the drug to the affected spots in the brain. The blood–brain barrier (BBB), a filtering mechanism of the capillaries that carries blood to the brain, prevents the drug from reaching the brain. “At first we tried intravenous injection, but the drug ended up getting trapped inside the lungs. So we tried some other ways, which also failed.” Na then adopted a different approach, injecting mesenchymal stem cells directly into the hippocampus, which is located in the inner temporal lobe of the brain. The approach worked. Nine people have so far been tested with the method, and he confirmed that the symptoms of Alzheimer’s disease can be relieved with repeated injections. “The more we study stem cells, the more we are amazed by what they are capable of,” he said. “Stem cells can transform into what is needed to fix any health problem. They are like a panacea.”
Stem cell breakthrough: blessing or curse?
The clinical trials, if successful, will be groundbreaking for the 48 million Alzheimer’s patients in the world. But even if the trials fail, he believes they will put researchers a step closer to successfully using stem cells to conquer the disease. Na also said Alzheimer’s research could raise a major ethical issue later for mankind. “What we use now is mesenchymal stem cells, which are not capable of differentiating into neurons. But, sooner or later, scientists will find ways to use neural stem cells, which are capable of doing so, on humans,” Na said. “When it comes to treating Alzheimer’s disease, with mesenchymal stem cells, doctors can only relieve its symptoms. On the other hand, if they use neural stem cells with better technologies, they may bring about results that are unimaginable right now. For instance, they may bring back memories that you don’t want to remember.” It will be difficult to get approval from governments for using neural stem cells, but he thinks that scientists will, somehow, someday. He also believes, considering the current pace of development, with stem cell technologies, scientists will eventually be able to control the human lifespan and even create humans in the not-so-distant future. “But that is a line that no one should cross,” Na said. “It will erase human dignity because you can kill and make humans as you want. What if the technology falls into the hands of bad people? It will be disastrous for the whole world. Think about it.” “Perhaps it is time for scientists and governments to start thinking about how to ensure the good use of stem cell technologies, which are expected to have profound impacts on mankind.”
Journey into the brain
Na is one of the most renowned Alzheimer’s disease experts in Korea. In 1995, when the disease was barely understood in the country, he established a cognitive test for Korea, called Seoul Neuropsychological Screening Battery. The cognitive test is now the most commonly used one in the country. Over the past 20 years, the scholar has also published more than 250 articles on dementia in Korea and abroad, helping set up clinical methods for the disease, especially in the area of vascular dementia. After Alzheimer’s disease, which is identified as the cause for 70 percent of dementia, vascular dementia is the second most common cause (about 20 percent). And thanks to Na’s efforts, vascular dementia, which is caused by problems in the blood supply to the brain, can be managed today better with proper treatments. His journey as a brain researcher started with an intense curiosity, he said. “When I was a student at Seoul National University College of Medicine, I was just fascinated by the brain, where each lobe serves different functions,” Na said. “At that time, the school’s neurology department was new and few students chose the major, but I did simply because I liked it a lot.” After obtaining his doctor of medicine degree in 1982, Na went to the University of Western Ontario in Canada to study Alzheimer’s disease as a research fellow, and then to the University of Florida to study the field more deeply. When he returned to Korea in 1995, dementia was still considered a natural consequence of aging, and there were no clinical guidelines or facilities for patients with the disease. So he started to develop guidelines or facilities to help patients and their families. “At some point, I started to pursue one goal in my life: conquering dementia. Finally, the goal may be within my grasp,” he said.