Human umbilical cord blood cells found to enhance survival and maturation of key brain cells

 Laboratory culture (in vitro) studies examining the activity of human umbilical cord blood cells (HUCB) on experimental models of central nervous system aging, injury and disease, have shown that HUCBs provide a 'trophic effect' (nutritional effect) that enhances survival and maturation of hippocampal neurons harvested from both young and old laboratory animals.

"As we age, cognitive function tends to decline," said Alison E. Willing, PhD, a professor in the University of South Florida's (USF) Department of Neurosurgery and Brain repair and lead author for a study published in the current issue of Aging and Disease. "Changes in cognitive function are accompanied by changes in the hippocampus, an area of the brain where long term memory, as well as other functions, are located, an area of the brain among those first to suffer the effects of diseases such as Alzheimer's disease."

According to Dr. Willing and her USF co-authors, these changes contribute to stroke and dementia in the aging population when neural cells become more susceptible to stressors and disease processes. Because HUCB cells have received attention as an alternative source of stem cells that have been studied and shown to be effective with wide therapeutic potentials, how the cells might be used to repair the diseased, as well as normally aging brain, has become an important question.

"It is important to understand how these cells may be manipulated to support hippocampal function in order to develop new therapies," she explained. "Accordingly, this study sought to examine the potential for HUCBs to enhance proliferation and increase survival of hippocampal cells derived from aging adult rat brains."

The study found that HUCBs were not only able to protect hippocampal neurons taken from the brains of young adult and aged rats, but also promoted the growth of dendrites — the branching neurons acting as signaling nerve communication channels — as well as induced the proliferation hippocampal neurons.

"These protective effects may be a function of growth factors and cytokines (a small signaling protein linked to the inflammatory response) produced by the HUCB cells," observed Dr. Willing.

The researchers also reported that the difference between HUCB-treated cultures and non-treated cultures was "more dramatic in the older adult rat brain cultures" than in those younger rats. Further, they speculated that synapses — the communication links between neuronal cells -may have been forming in the cultures.

They concluded that HUCB cells benefit aging adult hippocampal neurons by 'increasing their survival, growth, differentiation, maturation and arborization' (branching).

"The mechanisms by which HUCB cells extend the life of hippocampal cells may include enhancing the proliferative capacity of the cells or protecting existing and newly generated neurons from damage and death," concluded Dr. Willing.

According to Dr. John Sladek, professor of neurology at the University of Colorado School of Medicine, this study is important for its potential contribution to regenerative medicine's future ability to benefit from an important source for stem cells, the umbilical cord.

"The fact that HUCBs enhanced the survival of — and maturation of — hippocampal neurons has profound implications for the treating brain injury and degenerative diseases such as Alzheimer's disease, ALS and Parkinson's disease," said Dr. Sladek.

Study contributors included: Ning Chen, Jennifer Newcomb, Svitlana Garbuzova-Davis, Cyndy Davis Sanberg, and Paul R. Sanberg.


Journal Reference:

  1. Ning Chen, Jennifer Newcomb, Svitlana Garbuzova-Davis, Cyndy Davis Sanberg, Paul R. Sanberg, and Alison E. Willing. Human Umbilical Cord Blood Cells Have Trophic Effects on Young and Aging Hippocampal Neurons in Vitro. Aging and Disease, Volume 1, Number 3; 173-190, 2010

New mechanism links cellular stress and brain damage

A new study uncovers a mechanism linking a specific type of cellular stress with brain damage similar to that associated with neurodegenerative disease. The research, published by Cell Press in the Dec. 9 issue of the journal Neuron, is the first to highlight the significance of the reduction of a specific calcium signal that is directly tied to cell fate.

Body cells are constantly exposed to various environmental stresses. Although cells possess some natural defenses, excessive stress can lead to a type of cell death called apoptosis. "It is thought that excessive stress impacts brain function by inducing neuronal apoptosis and may play a role in neurodegenerative diseases such as Alzheimer's disease and Huntington's disease (HD)," explains senior study author, Dr. Katsuhiko Mikoshiba, from the Laboratory for Developmental Neurobiology at RIKEN Brain Science Institute.

HD is also associated with abnormal calcium signaling and the accumulation of misfolded proteins. Altered function of an intracellular structure called the endoplasmic reticulum (ER) that plays a key role in protein "quality control" and is a critical regulator of intracellular calcium signaling has been implicated in HD pathogenesis, but the specific underlying mechanisms linking ER stress with calcium and apoptosis are poorly understood.

Dr. Mikoshiba and colleagues demonstrated that a neuronal protein called inositol 1,4,5-trisphosphate receptor 1 (IP3R1) which regulates cellular calcium signaling was destroyed by ER stress and subsequently induced neuronal cell death and brain damage. The researchers went on to show that a protective "chaperone" protein called GRP78 positively regulated IP3R1 and that ER stress led to an impaired IP3R1-GRP78 interaction, which has also been observed in an animal model of HD.

"Based on our observation that the functional interaction between IP3R1 and GRP78 is impaired during ER stress and in the HD model, we propose that IP3R1 functions to protect the brain against stress and that the linkage between ER stress, IP3/calcium signaling, and neuronal cell death are associated with neurodegenerative disease." concludes Dr. Mikoshiba.


Journal Reference:

  1. Takayasu Higo, Kozo Hamada, Chihiro Hisatsune, Nobuyuki Nukina, Tsutomu Hashikawa, Mitsuharu Hattori, Takeshi Nakamura, Katsuhiko Mikoshiba. Mechanism of ER Stress-Induced Brain Damage by IP3 Receptor p865. Neuron, 2010; 68 (5): 865-878 DOI: 10.1016/j.neuron.2010.11.010

Stroke damage reversed by jumpstarting nerve fibers

A new technique that jump-starts the growth of nerve fibers could reverse much of the damage caused by strokes, researchers report in the Jan. 7, 2011, issue of the journal Stroke.

"This therapy may be used to restore function even when it's given long after ischemic brain damage has occurred," senior author Gwendolyn Kartje, MD, PhD, and colleagues write.

The article has been published online in advance of the print edition.

Kartje is director of the Neuroscience Institute of Loyola University Chicago Stritch School of Medicine and chief of neuroscience research at Edward Hines Jr. VA Hospital.

Currently doctors can do little to limit stroke damage after the first day following a stroke. Most strokes are ischemic (caused by blood clots). A drug called tPA can limit damage but must be given within the first three hours for the greatest benefit — and most patients do not receive treatment within that time frame.

Kartje and colleagues report on a treatment called anti-Nogo-A therapy. Nogo-A is a protein that inhibits the growth of nerve fibers called axons. It serves as a check on runaway nerve growth that could cause a patient to be overly sensitive to pain, or to experience involuntary movements. (The protein is called Nogo because it in effect says "No go" to axons.) In anti-Nogo therapy, an antibody disables the Nogo protein. This allows the growth of axons in the stroke-affected side of the body and the restoration of functions lost due to stroke.

Kartje and colleagues report dramatic results of anti-Nogo therapy in rats that had experienced medically induced strokes. Researchers trained rats to reach and grab food pellets with their front paws. One week after experiencing a stroke, the animals all had significant deficits in grabbing pellets with their stroke-impaired limbs. There was little improvement over the next eight weeks.

Nine weeks after their stroke, six rats received anti-Nogo therapy, four rats received a control treatment consisting of an inactive antibody and five rats received no treatment. Nine weeks later, rats that had received anti-Nogo therapy regained 78 percent of their ability to grab pellets. By comparison, rats receiving no treatment regained 47 percent of that ability, and rats receiving the control treatment of inactive antibodies regained 33 percent of their pre-stroke performance.

Subsequent examination of brain tissue found that the rats that received anti-Nogo therapy experienced significant sprouting of axons.

Researchers wrote that anti-Nogo-A therapy "can induce remarkable compensatory sprouting and fiber growth, indicating the responsiveness of the chronically injured brain to form new neural networks under the proper growth conditions."

The findings "are of great clinical importance," researchers concluded. Anti-Nogo-A therapy "may benefit not only victims of spinal-cord injury or patients in the early stage of stroke recovery, but also patients in later stages who suffer from neurological disability due to brain damage from stroke or other causes."

In a Phase I trial including other centers, patients paralyzed by spinal-cord injuries are receiving anti-Nogo therapy. The trial is sponsored by the pharmaceutical company Novartis.

Kartje's study co-authors are first author Shih-Yen Tsai, MD, PhD, and Catherine Papadopoulos, PhD, of Hines VA Hospital and Martin Schwab, PhD, of the University of Zurich.

The study was funded by the Department of Veterans Affairs and the National Institute of Neurological Disorders and Stroke.


Journal Reference:

  1. S.-Y. Tsai, C. M. Papadopoulos, M. E. Schwab, G. L. Kartje. Delayed Anti-Nogo-A Therapy Improves Function After Chronic Stroke in Adult Rats. Stroke, 2010; DOI: 10.1161/STROKEAHA.110.590083

Bone marrow stromal stem cells may aid in stroke recovery

A research study from the Farber Institute for Neurosciences and the Department of Neuroscience at Thomas Jefferson University determines bone marrow stromal stem cells may aid in stroke recovery. The results can be found in Cell Transplantation — The Regenerative Medicine Journal.

The study examining the effects of a systematic administration of either rat (allogenic) or human (xenogenic) bone marrow stem cells (MSC) administered to laboratory rats one day after their simulated strokes found "significant recovery" of motor behavior on the first day. Early administration was found to be more effective than administration seven days after the simulated strokes.

"The timing of stem cell treatment was critical to the magnitude of the positive effects," said the study's lead author, Lorraine Iacovitti, Ph.D., professor, Department of Neuroscience at Jefferson Medical College of Thomas Jefferson University. "In the host animals we found profound changes and preserved brain structure along with long-lasting motor function improvement."

According to Dr. Iacovitti, there has been little research into just how stem cell transplantation modifies inflammatory and immune effects as well as promotes regenerative effects, such as blood vessel growth. They observed increased activation of microglia as well as modification of the circulating levels of cytokines and growth factors, including elevated VEGF and new blood vessel formation (angiogenesis) following transplantation.

"The mechanism through which MSCs achieve these remarkable effects remains elusive," said Dr. Iacovitti. "It is possible that activated glia cells (nonneuronal cells that perform a number of tasks in the brain) may play some role in the response, perhaps by partitioning off the infarcted region and limiting the spread of ischemic brain damage without inducing scar formation."

The research team concluded that there was "little doubt" that the administration of stem cells can modify the cellular and molecular landscape of the brain and blood, limiting damage and protecting the stroke-injured brain.

Other Jefferson researchers participating in this study included Robert Rosenwasser, M.D. (Neurological Surgery) and Ming Yang, M.D., Ph.D. (Neuroscience).


Journal Reference:

  1. Ming Yang, Xiaotao Wei, Jing Li, Lynn A. Heine, Robert Rosenwasser, Lorraine Iacovitti. Changes in Host Blood Factors and Brain Glia Accompanying the Functional Recovery After Systemic Administration of Bone Marrow Stem Cells in Ischemic Stroke Rats. Cell Transplantation, 2010; 19 (9): 1073 DOI: 10.3727/096368910X503415

Eye movement problems common cause of reading difficulties in stroke patients

Visual problems can affect up to two thirds of stroke patients, but can sometimes go undetected if patients do not recognise them as an after-effect of the condition or if they are unable to communicate the problem to their medical team or families.

Research has often focused on visual field loss, caused by an interruption in the pathways that deliver an image from the eye to the brain for processing. Study led by scientists at Liverpool, however, has shown that damage to the nerve supply that controls eye movement is also a common problem after a stroke. Impaired eye movement can impact on the ability to follow a moving object or read words on a page.

Treatments include exercises to strengthen the eye muscles when looking at objects close to the face, as well as prisms that can be fitted to glasses to join double vision. The research highlights the need for developing stricter assessment methods to ensure vision problems are detected and appropriately identified as the after-effects of stroke as opposed to a symptom of old age.

Other vision problems include central vision loss, a complete loss of vision in one or both eyes, and 'higher' visual processing problems, in which the image is formed by the eye and transmitted to the brain, but cannot be interpreted properly.

Dr Fiona Rowe, from the University's Directorate of Orthoptics and Vision Science, said: "If a stroke patient has vision problems it can impact on the rest of their rehabilitation in a variety of ways, including reading difficulties and moving around properly. It is vital that health care services are aware of the different vision problems that stroke patients can face and have clear guidelines on identifying where the condition originates, whether it is in the eye, brain or the connecting pathways.

"Quite often patients do not connect difficulties with reading with the after-effects of stroke and so they can be missed. It is important, therefore, that health workers ask the right questions of the patient in order to understand whether the condition is as result of a stroke or if the problem existed prior to this. We hope this new research will increase awareness of vision problems in stroke patients and encourage those affected by the condition to consult medics with any difficulties they experience."

The research will be presented at the UK Stroke Forum conference on 2 December and published in the International Journal of Stroke in the New Year.

Collaborators in the research include: Altnagelvin Hospitals HHS Trust; NHS Ayrshire and Arran; Royal United Hospitals Bath NHS Trust Sandwell and West Birmingham NHS Trust; East Lancashire Hospitals NHS Trust; Bury PCT; Derby Hospitals NHS Trust; Durham and Darlington Hospitals NHS Foundation Trust; Ipswich Hospital NHS Trust; Gloucestershire Hospitals NHS Foundation Trust; St Helier General Hospital; United Lincolnshire Hospitals NHS Trust; Nottingham University Hospital NHS Trust; Oxford Radcliffe Hospitals NHS Trust; Salford Primary Care Trust; Sheffield Teaching Hospitals NHS Foundation Trust; Swindon and Marlborough NHS Trust; Taunton and Somerset NHS Trust; Warrington and Halton Hospitals NHS Foundation Trust; Wrightington, Wigan and Leigh NHS Trust.

Virtual biopsy may allow earlier diagnosis of brain disorder in athletes

In a study of ex-pro athletes, researchers found that a specialized imaging technique called magnetic resonance spectroscopy (MRS) may help diagnose chronic traumatic encephalopathy (CTE), a disorder caused by repetitive head trauma that currently can only be definitively diagnosed at autopsy. Results of the study were presented at the annual meeting of the Radiological Society of North America (RSNA).

"The devastating effects of brain injuries suffered by pro football players who repeatedly suffered concussions and subconcussive brain trauma during their careers have put the spotlight on CTE," said Alexander P. Lin, Ph.D., a principal investigator at the Center for Clinical Spectroscopy at Brigham and Women's Hospital in Boston. "However, blows to the head suffered by all athletes involved in contact sports are of increasing concern."

According to the Centers for Disease Control and Prevention, an estimated 3.8 million sports- and recreation-related concussions occur in the U.S. each year. In addition, subclinical concussions — injuries that cannot be diagnosed as concussions but have similar effects — are often unrecognized.

Studies have shown that individuals who suffer repetitive brain trauma are more likely to experience ongoing problems, from permanent brain damage to long-term disability.

CTE is a degenerative brain disease caused by repeated brain trauma and marked by a buildup of abnormal proteins in the brain. CTE has been associated with memory difficulty, impulsive and erratic behavior, depression and eventually, dementia.

"Cumulative head trauma invokes changes in the brain, which over time can result in a progressive decline in memory and executive functioning in some individuals," Dr. Lin said. "MRS may provide us with noninvasive, early detection of CTE before further damage occurs, thus allowing for early intervention."

In Dr. Lin's study, conducted in collaboration with the Boston University Center for the Study of Traumatic Encephalopathy (CSTE), five retired professional male athletes from football, wrestling and boxing with suspected CTE and five age- and size-matched controls between the ages of 32 and 55 were examined with MRS. In MRS, sometimes referred to as "virtual biopsy," a powerful magnetic field and radio waves are used to extract information about chemical compounds within the body, using a clinical MR scanner.

The results revealed that compared with the brains of the control patients, the brains of the former athletes with suspected CTE had increased levels of choline, a cell membrane nutrient that signals the presence of damaged tissue, and glutamate/glutamine, or Glx. MRS also revealed altered levels of gamma-aminobutyric acid (GABA), aspartate, and glutamate in the brains of former athletes.

"By helping us identify the neurochemicals that may play a role in CTE, this study has contributed to our understanding of the pathophysiology of the disorder," Dr. Lin said.

For example, the amino acid and neurotransmitter glutamate is involved in most aspects of normal brain function and must be present in the right places and at the right concentration in order for the brain to be healthy — too much or too little can be harmful.

"Being able to diagnose CTE could help athletes of all ages and levels, as well as war veterans who suffer mild brain injuries, many of which go undetected," Dr. Lin said.

Results of CSTE neuropathological studies of retired football players and other athletes have led to significant changes in the NFL, as well as collegiate and youth sports. Recently, the researchers found evidence of CTE in 21-year-old Owen Thomas, the University of Pennsylvania football captain who committed suicide in April 2010.

Coauthors are Saadallah Ramadan, Ph.D., Hayden Box, B.S., Peter Stanwell, Ph.D., and Robert Stern, Ph.D. Dr. Lin's research team is led by Carolyn Mountford, D.Phil. Other collaborators include Ann McKee, M.D., Robert Cantu, M.D., and Christopher Nowinski.

Color-changing 'blast badge' detects exposure to explosive shock waves

Mimicking the reflective iridescence of a butterfly's wing, investigators at the University of Pennsylvania School of Medicine and School of Engineering and Applied Sciences have developed a color-changing patch that could be worn on soldiers' helmets and uniforms to indicate the strength of exposure to blasts from explosives in the field. Future studies aim to calibrate the color change to the intensity of exposure to provide an immediate read on the potential harm to the brain and the subsequent need for medical intervention.

The findings are described in the ahead-of-print online issue of NeuroImage.

"We wanted to create a 'blast badge' that would be lightweight, durable, power-free, and perhaps most important, could be easily interpreted, even on the battlefield," says senior author Douglas H. Smith, MD, director of the Center for Brain Injury and Repair and professor of Neurosurgery at Penn. "Similar to how an opera singer can shatter glass crystal, we chose color-changing crystals that could be designed to break apart when exposed to a blast shockwave, causing a substantial color change."

D. Kacy Cullen, PhD, assistant professor of Neurosurgery, and Shu Yang, PhD, associate professor of Materials Science and Engineering, were co-authors with Smith.

Blast-induced traumatic brain injury is the "signature wound" of the current wars in Iraq and Afghanistan. However, with no objective information of relative blast exposure, soldiers with brain injury may not receive appropriate medical care and are at risk of being returned to the battlefield too soon.

"Diagnosis of mild traumatic brain injury [TBI] is challenging under most circumstances, as subtle or slowly progressive damage to brain tissue occurs in a manner undetectable by conventional imaging techniques," notes Cullen. There is also a debate as to whether mild TBI is confused with post-traumatic stress syndrome. "This emphasizes the need for an objective measure of blast exposure to ensure solders receive proper care," he says.

Sculpted by Lasers

The badges are comprised of nanoscale structures, in this case pores and columns, whose make-up preferentially reflects certain wavelengths. Lasers sculpt these tiny shapes into a plastic sheet.

Yang's group pioneered this microfabrication of three-dimensional photonic structures using holographic lithography. "We came up the idea of using three-dimensional photonic crystals as a blast injury dosimeter because of their unique structure-dependent mechanical response and colorful display," she explains. Her lab made the materials and characterized the structures before and after the blast to understand the color-change mechanism.

"It looks like layers of Swiss cheese with columns in between," explains Smith. Although very stable in the presence of heat, cold or physical impact, the nanostructures are selectively altered by blast exposure. The shockwave causes the columns to collapse and the pores to grow larger, thereby changing the material's reflective properties and outward color. The material is designed so that the extent of the color change corresponds with blast intensity.

The blast-sensitive material is added as a thin film on small round badges the size of fill-in-the-blank circles on a multiple-choice test that could be sewn onto a soldier's uniform.

In addition to use as a blast sensor for brain injury, other applications include testing blast protection of structures, vehicles and equipment for military and civilian use.

This research was funded by the Philadelphia Institute of Nanotechnology, and supported in part by the Office of Naval Research and the Air Force Office of Scientific Research.


Journal Reference:

  1. D. Kacy Cullen, Yongan Xu, Dexter V. Reneer, Kevin D. Browne, James W. Geddes, Shu Yang, Douglas H. Smith. Color changing photonic crystals detect blast exposure. NeuroImage, 2010; DOI: 10.1016/j.neuroimage.2010.10.076

Adding face shields to helmets could help avoid blast-induced brain injuries

More than half of all combat-related injuries sustained by U.S. troops are the result of explosions, and many of those involve injuries to the head. According to the U.S. Department of Defense, about 130,000 U.S. service members deployed in Iraq and Afghanistan have sustained traumatic brain injuries — ranging from concussion to long-term brain damage and death — as a result of an explosion. A recent analysis by a team of researchers led by MIT reveals one possible way to prevent those injuries — adding a face shield to the helmet worn by military personnel.

In a paper to be published November 22  in the Proceedings of the National Academy of Sciences, Raul Radovitzky, an associate professor in MIT's Department of Aeronautics and Astronautics, and his colleagues report that adding a face shield to the standard-issue helmet worn by the vast majority of U.S. ground troops could significantly reduce traumatic brain injury, or TBI. The extra protection offered by such a shield is critical, the researchers say, because the face is the main pathway through which pressure waves from an explosion are transmitted to the brain.

In assessing the problem, Radovitzky, who is also the associate director of MIT's Institute for Soldier Nanotechnologies, and his research team members recognized that very little was known about how blast waves interact with brain tissue or how protective gear affects the brain's response to such blasts. So they created computer models to simulate explosions and their effects on brain tissue. The models integrate with unprecedented detail the physical aspects of an explosion, such as the propagation of the blast wave, and the anatomical features of the brain, including the skull, sinuses, cerebrospinal fluid, and layers of gray and white matter.

"There is a community studying this problem that is in dire need of this technology," says Radovitzky, who is releasing the computer code for the creation of the models to the public this week. In doing so, he hopes the models will be used to identify ways to mitigate TBI, which has become prominent because advances in protective gear and medicine have meant that more service members are surviving blasts that previously would have been fatal.

To create the models, Radovitzky collaborated with David Moore, a neurologist at the Defense and Veterans Brain Injury Center at Walter Reed Army Medical Center, who used magnetic resonance imaging to model features of the head. The researchers then added data collected from colleagues' studies of how the brain tissue of pigs responds to mechanical events, such as shocks. They also included details about what happens to the chemical energy that is released upon detonation (outside the brain) that instantly converts into thermal, electromagnetic and kinetic energy that interacts with nearby material, such as a soldier's helmet.

The researchers recently used the models to explore one possibility for enhancing the helmet currently worn by most ground troops, which is known as the Advanced Combat Helmet, or ACH: a face shield made of polycarbonate, a type of transparent armor material. They compared how the brain would respond to the same blast wave simulated in three scenarios: a head with no helmet, a head wearing the ACH, and a head wearing the ACH with a face shield. In all three simulations, the blast wave struck the person from the front.

The analysis revealed that although the ACH — as currently designed and deployed — slightly delayed the arrival of the blast wave, it didn't significantly mitigate the wave's effects on brain tissue. After the researchers added a conceptual face shield in the third simulation, the models showed a significant reduction in the magnitude of stresses on the brain because the shield impeded direct transmission of blast waves to the face.

Radovitzky hopes that the models will play a major role in developing protective gear not only for the military, but also for researchers studying the effects of TBI in the civilian population as a result of car crashes and sports injuries. While the study was limited to a single set of blast characteristics, future simulations will study different kinds of blast conditions, such as angle and intensity, as well as the impact of blast waves on the neck and torso, which have been suggested as a possible indirect pathway for brain injury.


Journal Reference:

  1. Nyein, M., Jason, A., Yu. L., Pita, C., Joannopoulos, J., Moore, D., Radovitzky, R. In silico investigation of intracranial blast mitigation with relevance to military traumatic brain injury. Proceedings of the National Academy of Sciences, 22 November, 2010

Protein found to predict brain injury in children on extra-corporeal membrane oxygenation (ECMO) life support

Johns Hopkins Children's Center scientists have discovered that high blood levels of a protein commonly found in the central nervous system can predict brain injury and death in critically ill children on a form of life support called extra-corporeal membrane oxygenation or ECMO.

ECMO, used to temporarily oxygenate the blood of patients whose heart and lungs are too weak or damaged to do so on their own, is most often used as a last resort because it can increase the risk for brain bleeding, brain swelling, stroke and death in some patients.

A detailed report of the Hopkins team's findings is published ahead of print Nov. 4 in the journal Pediatric Critical Care Medicine.

Following 22 ECMO patients, ranging from two days to 9 years of age, the researchers found that those with abnormally high levels of glial fibrillary acidic protein (GFAP) were 13 times more likely to die and 11 times more likely to suffer brain injury than children with normal GFAP levels. GFAP levels are already used as a marker of neurologic damage in adults who suffer strokes and traumatic brain injuries.

Although preliminary, the team's findings may pave the way to a much-needed way to monitor the precarious neurologic status of children on ECMO without using imaging tests like ultrasounds or CT scans. Periodic blood tests measuring GFAP levels may be one such tool to monitor brain function and help ward off brain injury and death, the researchers say.

"A simple, fast and easy-to-use test has been needed to monitor, predict and prevent brain damage in children on ECMO because these children are unresponsive or heavily sedated, and doctors cannot easily gauge their neurologic function," says study lead investigator Melania Bembea, M.D., M.P. H., a pediatric critical-care specialist at Hopkins Children's.

"Early detection of brain injury can help us prevent further harm by changing medication doses and rapidly weaning the patient from ECMO support," she adds.

The findings may have implications beyond ECMO, the researchers say, as they offer a way to monitor brain damage in other high-risk situations, including heart surgery and severely premature birth.

"Our long-term goal is to make lifesaving therapies like ECMO and heart surgery safer and more effective by improving protection of the brain, and GFAP and other biomarkers can give us a much-needed benchmark around which we can make these therapies safer," says senior investigator Allen Everett, M.D., a cardiologist at Hopkins Children's.

In the study, seven of the 22 children on ECMO developed brain bleeding or brain swelling, five of whom died subsequently. These children had much higher peak levels of GFAP than children without brain injury — 5.9 nanograms per milliliter of blood compared to 0.09 in children without brain injury. GFAP levels were also markedly higher among eight of the 22 children in the study who had poor neurologic outcomes after ECMO (3.6 ng/ml) than in those children who had good neurologic outcomes (0.09 ng/ml).

Researchers also measured GFAP levels among healthy children and among newborns without neurologic injuries. Their median GFAP level was 0.055 nanograms per milliliter of blood and as high as 0.436 in some cases. By comparison, overall GFAP levels in children with neurologic injuries were 13 times greater than GFAP levels in healthy children.

The researchers caution that their findings should be replicated in a larger trial with more patients and that future studies must clarify the relationship between a rise in GFAP levels and the onset of brain injury. In the current study, GFAP levels rose sharply in some patients one or two days before their brain damage was discovered on ultrasound.

ECMO is used in about 1,000 children each year. Between 10 percent and 60 percent of children who survive ECMO suffer neurologic damage either because of their underlying disease or complications during ECMO therapy, the researchers say.

Hopkins Children's is Maryland's only hospital providing pediatric ECMO service.

The research was funded by the National Institutes of Health.

Other investigators in the study included William Savage, M.D., John Strouse, M.D., Ph.D., Jamie Schwartz, M.D., Ernest Graham, Carol Thompson, M.B.A., M.S., all of Hopkins.

Brain cells called pericytes become a player in Alzheimer's, other diseases

Cells in the brain called pericytes that have not been high on the list of targets for treating diseases like Alzheimer's may play a more crucial role in the development of neurodegenerative diseases than has been realized.

The findings, published Nov. 4 in Neuron, cast the pericyte in a surprising new role as a key player shaping blood flow in the brain and protecting sensitive brain tissue from harmful substances. By manipulating pericyte levels, scientists were able to re-create in the brains of mice an array of abnormalities that mirror in striking fashion the brain difficulties that occur in many people as they age.

"For 150 years these cells have been known to exist in the brain, but we haven't known exactly what they are doing in adults," said Berislav Zlokovic, M.D., Ph.D., the neuroscientist who led the research at the University of Rochester Medical Center. "It turns out that pericytes are very important for helping maintain a brain environment crucial to the health of neurons. The pericyte offers us an exciting new target for new treatments for neurodegenerative diseases."

While damage to neurons oftentimes causes the symptoms that patients experience — dementia in Alzheimer's, and movement difficulties in Parkinson's disease, for instance — neuroscientists know that neurons depend on a broad variety of factors coming together to create just the right environment to thrive. Zlokovic himself has pioneered the concept that impaired blood flow and flaws in the blood-brain barrier may play a huge role in the development of diseases like Alzheimer's through their impact on neurons.

In the most recent findings from Zlokovic's laboratory, the two first authors who contributed equally to the research, graduate student Robert Bell and M.D./Ph.D. student Ethan Winkler, teased out the role of the pericyte in the process. Pericytes ensheath the smallest blood vessels in the brain, wrapping around capillaries like ivy wrapping around a pipe and helping to maintain the structural integrity of the vessels.

It turns out that pericytes do much more. The team found that the cells are central to determining the amount of blood flowing in the brain and play an instrumental role in maintaining the barrier that stops toxic substances from leaking out of the capillaries and into brain tissue. When the team reduced the number of working pericytes in the brains of mice, the effects included reduced blood flow, greater exposure of brain tissue to toxic substances, impaired learning and memory, and damage to the neurons — all phenomena that are more likely to happen to people as they age.

"This work shows that other cells in the brain have a tremendous effect on the neurons, even driving the neurodegenerative process," said Winkler. "This is very exciting."

To make the finding, the team studied mice in which the normal number of pericytes is reduced dramatically. Scientists studied young mice (about one month old), middle-aged mice (about six to eight months old), and older mice (14 to 16 months old).

The amount of damage that occurred depended on age, with the worst damage occurring consistently in the oldest mice — a finding that parallels what happens with people, whose brains are much more likely to suffer neurodegenerative conditions like Alzheimer's or Parkinson's disease as they age. The mice experienced an array of problems that match up pretty closely with the brain abnormalities that people with neurodegenerative conditions like Alzheimer's experience.

Among the findings in mice with reduced levels of pericytes:

Cerebral blood flow was reduced, and the problem worsened as the mice got older. Older mice had 50 percent less blood flow than mice of similar age with a normal number of pericytes. Younger and middle-age mice had 23 percent less and 33 to 37 percent less blood flow, respectively.

Serum proteins and toxic molecules were much more likely to gain entry to the brain, thanks to a breakdown of the blood-brain barrier. For instance, molecules such as hemosiderin, fibrin, thrombin and plasmin are toxic in the brain and are normally not found in brain tissue. The older mice had 20 to 25 times as much accumulation of these toxins in their brain tissue as their normal counterparts; the younger and middle-age mice had three times as much and 8 to 10 times as much, respectively.

The breakdown in the blood-brain barrier was especially evident in blood vessel structures known as tight junctions, which play an important role in stopping harmful substances from reaching brain tissue. Their activity in the older mice was down 40 to 60 percent in older and middle-age mice compared to their normal counterparts.

Compared to normal mice, the mice with fewer pericytes had structural damage to their neurons, including loss of dendritic length and spine density. Again, the amount of damage correlated to the age of the mice, with older mice showing more damage. The team also documented impaired learning and memory in the middle-age and the older mice, but not the youngest mice.

"Our findings show that chronic vascular damage due to pericyte loss results in neurodegeneration," said Zlokovic, who is Dean's Professor in the Departments of Neurosurgery and Neurology and director of the Center for Neurodegenerative and Vascular Brain Disorders. "It may be that a vascular insult is common to many different types of neurodegenerative processes and may be significant in causing the symptoms seen in diseases such as Alzheimer's and amyotrophic lateral sclerosis."

The findings could cause neuroscientists to change their views of the origins of many neurodegenerative disorders, said Bell, who notes that a recently developed tool to track pericyte activity in the brain helped the team tackle the role of the pericyte.

"If all your tools are designed to study neurons, you'll learn a lot about neurons," Bell said. "We haven't known much about pericytes simply because we haven't had good tools to watch them. If you can't see the cells, it is difficult to study them."

In addition to Bell, Winkler, and Zlokovic, other authors include Abhay Sagare, Ph.D., senior instructor; Rashid Deane, Ph.D., research professor; Itender Singh, Ph.D., postdoctoral research associate; and Barbra LaRue, technical associate. The project was funded by the National Institute on Aging (grant # R37AG023084) and the National Institute of Neurological Disorders and Stroke (grant # R37NS34467).

Zlokovic is the founder of and an equity holder in three companies exploring new treatments for stroke and neurodegenerative diseases like Alzheimer's: Socratech, ZZ Alztech, and ZZ Biotech. The University of Rochester holds an equity interest in all three companies as well.


Journal Reference:

  1. Robert D. Bell, Ethan A. Winkler, Abhay P. Sagare, Itender Singh, Barb LaRue, Rashid Deane, Berislav V. Zlokovic. Pericytes Control Key Neurovascular Functions and Neuronal Phenotype in the Adult Brain and during Brain Aging. Neuron, 2010; 68 (3): 409 DOI: 10.1016/j.neuron.2010.09.043