Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

"Laser Tweezers" Permit Penn Researchers to Describe Microscopic Mechanical Properties of Blood Clots

27.06.2005


A Better Understanding of Clot Physiology Can Lead to More Effective Therapies

For the first time ever, using “laser tweezers,” the mechanical properties of an individual fiber in a blood clot have been determined by researchers at the University of Pennsylvania School of Medicine. Their work, led by John W. Weisel, PhD, Professor of Cell and Developmental Biology at Penn, and published in this week’s early online edition of the Proceedings of the National Academy of Sciences, provides a basis for understanding how the elasticity of the whole clot arises.

Clots are a three-dimensional network of fibrin fibers, stabilized by another protein called factor XIIIa. A blood clot needs to have the right degree of stiffness and plasticity to stem the flow of blood when tissue is damaged, yet be digestible enough by enzymes in the blood so that it does not block blood-flow and cause heart attacks and strokes.



Weisel and colleagues developed a novel way to measure the elasticity of individual fibrin fibers in clots-with and without the factor XIIIa stabilization. They used "laser tweezers"-essentially a laser-beam focused on a microscopic bead ‘handle’ attached to the fibers-to pull in different directions on the fiber.

The investigators found that the fibers, which are long and very thin, bend much more easily than they stretch, suggesting that clots deform in flowing blood or under other stresses primarily by the bending of their fibers.

Weisel likens the structure of a clot composed of fibrin fibers to a microscopic version of a bridge and its many struts. “Knowing the mechanical properties of each strut, an engineer can extrapolate the properties of the entire bridge,” he explains. “To measure the stiffness of a fiber, we used light to apply a tiny force to it and observed it bend in a light microscope, just as an engineer would measure the stiffness of a beam on a macroscopic scale. The mechanical properties of blood clots have been measured for many years, so now we can develop models to relate individual fiber and whole clot properties to understand mechanisms that can yield clots that have vastly different properties.”

He states that these findings have relevance for many areas: materials science, polymer chemistry, biophysics, protein biochemistry, and hematology. “We present the first determination of the microscopic mechanical properties of any polymer of this sort,” says Weisel. “What’s more, our choice of the fibrin clot has particular biological and clinical significance, since fibrin’s mechanical properties are essential for its functions in clotting and also are largely responsible for the pathology of thrombosis that causes most heart attacks and strokes.”

By understanding the microscopic mechanical properties of a clot and how that relates to its observed function within the circulatory system, researchers may be able to make predictions about clot physiology. For example, when clots are not stiff enough, problems with bleeding arise, and when clots are too stiff, there may be problems with thrombosis, which results when clots block the flow of blood.

But how can this knowledge be used to stop bleeding or too much clotting? “Once we understand the origin of the mechanical properties, it will be possible to modulate those properties,” explains Weisel. “If we can change a certain parameter perhaps we can make a clot that’s more or less stiff.” For example, various peptides or proteins, such as antibodies, bind specifically to fibrin, affecting clot structure. The idea would be to use such compounds in people to alter the properties of the clot, so it can be less obstructive and more easily dissolved.

“This paper shows how new technology has made possible a simple but elegant approach to determine the microscopic properties of a fibrin fiber, providing a basis for understanding the origin of clot elasticity, which has been a mystery for more than 50 years,” adds Weisel.

Weisel’s Penn co-authors are Jean-Philippe Collet, Henry Shuman, Robert E. Ledger, and Seungtaek Lee. Funding for the study was provided by the National Institutes of Health, Assistance Publique Hopitaux de Paris, and Parke-Davis. The authors claim no conflicts of interest.

Karen Kreeger | EurekAlert!
Further information:
http://www.uphs.upenn.edu

More articles from Life Sciences:

nachricht The birth of a new protein
20.10.2017 | University of Arizona

nachricht Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>