In Mouse Study, Researchers Discover New Mechanism for Clearing Blockages from Smallest Blood Vessels
Researchers have identified in mice a previously unknown protective mechanism by which the smallest blood vessels remove blood clots and other blockages from the brain. The findings provide insights into mechanisms that may be involved in age-related cognitive decline, Alzheimer's disease and recovery from stroke.
Balintfy: Uninterrupted blood flow is critical for brain function, and the brain has developed various mechanisms to maintain it. Blockages in the smallest blood vessels can be cleared by processes that disintegrate or wash them out. However, not all blockages are cleared completely. Dr. Suzana Petanceska at the National Institute of Aging explains that even tiny blockages in the smallest blood vessels — called microvessels — are bad.
Petanceska: Obstructed blood flow, even in the tiniest microvessel, has negative consequences on the connections between nerve cells, which is how they communicate and this is how the brain operates, and on the general health of individual nerve cells.
Balintfy: Persistent blockage can reduce or stop blood flow, limiting the supply of oxygen and nutrients to the surrounding tissue and nerve cells. This, in turn, can lead to impaired communications between nerve cells and ultimately cell death. Petanceska: So the body has developed a number of mechanisms to actually eliminate spontaneously occurring blood clots in these vessels. One is by what is called hemodynamic forces; clots are being just pushed through or squeezed through.
Balintfy: Another way, she adds, is the anti-clotting activity that exists in the bloodstream. Dr. Petanceska says scientists were curious to further investigate the ways that microvessels eliminate blood clots and to also examine the consequences when blood clots are not removed.
Petanceska: So, this was a study conducted in mice, where they used some cutting-edge new technology that allowed them to visualize.
Balintfy: She explains that researchers were surprised to see the cells known as endothelial cells basically reach out and surround clots and push them out of the microvessels after two to seven days. Petanceska: So this was fascinating; this was neither anticipated nor previously described.
Balintfy: The researchers also found that the ability to move the blockage out of the blood vessel diminished with age. Dr. Petanceska cautions these are early results and this discovery needs to be followed up by much more research; but she says it could have broad implications.
Petanceska: First, this may hold true in other organs, not just the brain, and it is important in terms of understanding microvascular resilience in a number of body organs. Second is that given that this process may be compromised and less efficient in the aged brain, this may be part of the mechanism by which age-related cognitive decline occurs in humans, and this may also play into what are the early pathogenic steps for neurodegenerative disorders such as Alzheimer's disease that has a huge cognitive component.
Balintfy: She says this also may play a role in processes that are required for recovery after stroke. The findings were described in a recent issue of Nature by researchers at Northwestern University Feinberg School of Medicine. For more on this study, visit www.nia.nih.gov. This is Joe Balintfy, National Institutes of Health, Bethesda, Maryland.
About This Audio Report
Reporter: Joe Balintfy
Sound Bite: Dr. Suzana Petanceska
Topic: brain, blood vessels, microvessel, capillary, blockage, stroke, Alzheimer’s Disease