MAY 04, 2016 8:53 AM PDT

Macrophages Repair Microbleeds in the Brain

WRITTEN BY: Kara Marker
Rupture of small blood vessels in the brain can cause hemorrhagic stroke and brain microbleeds, and finding the fastest repair mechanisms is the best way to treat these conditions. In a new study from Southwest University in China, researchers have discovered for the first time the unique role of macrophages in the repair broken blood vessels.
Vessels have the potential to rupture all over the body, but when they break in the brain, the damage is directly associated with cognitive decline from neurodegenerative diseases. Brain bleeds, detectable by MRI, are most common in elderly people, especially with dementia or cerebrovascular disease, but they can happen to anyone. Until the current study, published in Immunity, scientists were unsure about the level of capability the brain had to repair broken vessels.
Blood vessel repair process with the help of a macrophage
The research team from China used a multi-photon laser in a large zebrafish study to visualize how the organisms responded to vascular injury. The laser cleanly ruptured small blood vessels in the zebrafish brains, creating two clearly broken ends. Using a specialized microscope, the scientists incorporated in vivo time-lapse imaging to see how the vessels were repaired.
Approximately 30 minutes post-laser injury, a white blood cell called a macrophage arrived to the scene of rupture. These cells of the immune system are present in virtually every tissue of the body, providing multiple services relating to cellular clean-up, production of immune effector molecules, and engulfing harmful pathogens.
Upon arrival, the macrophage used two arm-like extensions, called filopodia or lamellipodia, to connect to both of the broken ends of the blood vessel. During a period of three hours, the macrophage reattached the broken ends using secreted adhesion molecules from the damaged blood vessel.
 “We confirmed that the macrophage mediates this repair through direct physical adhesion and generation of mechanical traction forces,” said PhD student Chi Liu. “This is a previously unexpected role of macrophages."
In addition to the macrophage repair seen in the zebrafish brain, similar repair occurred in ruptured blood vessels in the zebrafish fin. Another rare occurrence is two macrophages responding to the distress call emitted by ruptured small blood vessels. In this case, both of the macrophages begin the process but then quit, as if they left because they thought the other macrophage had the job covered. Additionally, there is a chance of microfilament depolymerization and inhibition of phosphatidylinositide 3-kinase (PI3K) or Rac1 activity. Researchers saw that these events disrupted macrophage-endothelial adhesion.
Lastly, the researchers also saw that zebrafish blood vessels can repair themselves independently of macrophages, but the process is much slower and less efficient.
Timeline of Blood Vessel Repair
Other aspects of vascular development and remodeling are shared between zebrafish and humans, so scientists are hopeful that this discovery will also be seen in humans. Further studies backing up this hypothesis will soon help scientists improve treatments for human vascular repair.
Sources: Lancet Neurology, Nature Reviews Immunology, Immunity, Cell Press/Southwest University
About the Author
  • I am a scientific journalist and enthusiast, especially in the realm of biomedicine. I am passionate about conveying the truth in scientific phenomena and subsequently improving health and public awareness. Sometimes scientific research needs a translator to effectively communicate the scientific jargon present in significant findings. I plan to be that translating communicator, and I hope to decrease the spread of misrepresented scientific phenomena! Check out my science blog:
You May Also Like
NOV 23, 2019
NOV 23, 2019
An app that can help better monitor Parkinson's Disease
A study published in the Journal of Parkinson's Disease describes how an app, called ‘SleepFit’, could be used as a useful tool in monitori...
JAN 08, 2020
Clinical & Molecular DX
JAN 08, 2020
MicroRNA emerges as a biomarker for migraines
Intense, debilitating pain that can last for days. Nausea, numbness and sensitivity to light. For people who experience migraines, it’s frustrating t...
JAN 16, 2020
Drug Discovery & Development
JAN 16, 2020
Fatty Acid Supplement Repairs Brain After Stroke in Mice
Researchers have found that supplements containing short chain fatty acids (SCFAs) may be able to help the brain recover from having a stroke. This comes a...
JAN 19, 2020
JAN 19, 2020
New Proteins Found in the Optical Processing of Lazy Eyes
Ophthalmology – Amblyopia: By Christine Law M.D.   Researchers in the Bear Lab at the Massachusetts Institute of Technology found surprising con...
FEB 06, 2020
Clinical & Molecular DX
FEB 06, 2020
Concussion detector could pick up concussions in athletes, right from the sidelines
Concussions are brain traumas caused by a blow to the head or a whiplash injury. The risk of concussions are greatly heightened in athletes playing high co...
FEB 26, 2020
Genetics & Genomics
FEB 26, 2020
Optogenetic Techniques Provide Insight Into ALS
In humans, motor neurons link thoughts with the motion of the body. Now researchers have learned more about how they are impacted by ALS....
Loading Comments...