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 Immune Defense Without Collateral Damage
23.01.2017 | Universität Basel

nachricht The interactome of infected neural cells reveals new therapeutic targets for Zika
23.01.2017 | D'Or Institute for Research and Education

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Tracking movement of immune cells identifies key first steps in inflammatory arthritis

23.01.2017 | Health and Medicine

Electrocatalysis can advance green transition

23.01.2017 | Physics and Astronomy

New technology for mass-production of complex molded composite components

23.01.2017 | Process Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>