Rutgers University

Study reveals new evidence of key mechanism in Alzheimer’s

/ Esteban Cortez / 1 Comment

In California, 690,000 people aged 65 and older are living with Alzheimer’s, a degenerative brain disease and the most common form of dementia. In the United States, 5.8 million people aged 65 and older live with Alzheimer’s disease. Alzheimer’s affects memory, thinking and behavior and symptoms eventually grow in severity to interfere with daily tasks.  

There is no cure for Alzheimer’s, which is why Rutgers scientists are examining human brain cells in mice to identify a pivotal mechanism that could result in a potential therapy for the disease. In a recent study, the Rutgers team found more clear-cut evidence of how the destructive proteins linked to Alzheimer’s disease attack human brain cells and destroy surrounding tissue. 

The researchers studied human brain immune cells injected into the brains of specially bred immunodeficient mice, creating what they called a human-mouse chimera. The researchers detailed what happened to specialized immune brain cells known as microglia after those cells were exposed to tau proteins—destructive substances believed to be involved in Alzheimer’s and other severe human brain diseases. 

“This provided an unprecedented opportunity to investigate the role of human microglia in brains as well as the cognitive impairment seen in Alzheimer’s Disease and Down syndrome, a genetic disorder with a high risk of developing Alzheimer’s disease,” said Peng Jiang, an associate professor in the Department of Cell Biology and Neuroscience at the Rutgers School of Arts and Sciences. 

By studying the process in the newly-developed brain—which allowed human cells to grow, develop and mature with appropriate functions—the scientists were able to witness and analyze a cellular brain attack that has been largely elusive up to this point. 

In autopsies, scientists have been able to study the brains of people who died from Alzheimer’s and have seen residues of tau proteins and cellular changes. The human-mouse brain chimera has allowed the Rutgers team to extract and see human cells in the actual process of deterioration. 

The mice in the study were specially bred to be immunodeficient so that they could receive implanted human cells without rejecting them due to normal immune defenses.  The immunodeficient mice were injected with human microglial cells and, later, with tau proteins, which are linked to the development of the brain disease. 

“Since microglial cells are one of the first cell responders when something goes wrong in the brain, we believe the changes we saw to be significant,” said Mengmeng Jin, a postdoctoral researcher in the Department of Cell Biology and Neuroscience at Rutgers and first author on the study. 

The California Institute for Regenerative Medicine (CIRM) is committed to investing at least $1.5 billion—more than double what CIRM funded between 2006 and 2020—in treatments that target conditions affecting the brain and central nervous system (CNS), including Alzheimer’s. 

Read the source release about the study here.  

Blocking spike in stem cell growth after brain injury may lessen memory decline, seizures

/ Todd Dubnicoff / Leave a comment

Survivors of traumatic brain injury (TBI) often suffer from debilitating, life changing symptoms like memory decline and epileptic seizures. Researchers had observed that following TBI, a stem cell-rich area of the brain provides a spike in new nerve cell growth, presumably to help replace damaged or destroyed brain cells. But, like a lot of things in biology, more is not always better. And a new report in Stem Cell Reports provides evidence that this spark of brain cell growth shortly after TBI may actually be responsible for post-injury seizures as well as long-term memory problems for people with this condition.The Rutgers University research team behind the study came to this counterintuitive conclusion by examining brain injury in laboratory rats. They showed that brain cells at the injury site that are known to play a role in memory had doubled in number within three days after injury. But a month later, these brain cells had decreased by more than half the amount seen in rats without injury. Neural stem cells, which develop into the mature cells found in the brain, showed this same up and down pattern, suggesting they were responsible for the loss of the brain cells. Lead scientist, professor Viji Santhakumar, described how these changes in brain cell growth lead to brain injury symptoms:

“There is an initial increase in birth of new neurons after a brain injury but within weeks, there is a dramatic decrease in the normal rate at which neurons are born, depleting brain cells that under normal circumstances should be there to replace damaged cells and repair the brain’s network,” she said in a press release. “The excess new neurons lead to epileptic seizures and could contribute to cognitive decline. It is normal for the birth of new neurons to decline as we age. But what we found in our study was that after a head injury the decline seems to be more rapid.”

The researchers next aimed to slow down this increase in nerve cell growth after injury. To accomplish this goal, they used an anti-cancer drug currently in clinical trials which has been known to block the growth and survival of new nerve cells. Sure enough, the drug blocked this initial, rapid burst in nerve cells in the rats, which prevented the long-term decline in the brain cells that are involved in memory decline. The team also reported that the rats were less vulnerable to seizures when this drug was administered.

“That’s why we believe that limiting this process might be beneficial to stopping seizures after brain injury,” Dr. Santhakumar commented.

Hopefully, these findings will one day help lessen these short- and long-term, life-altering symptoms seen after brain injury.