Featured Research

from universities, journals, and other organizations

New aspect of platelet behavior in heart attacks revealed: Clots can sense blood flow

Date:
November 7, 2012
Source:
University of Pennsylvania
Summary:
Atherosclerosis involves the build up of fatty tissue within arterial walls, creating unstable structures known as plaques. These plaques grow until they burst, rupturing the wall and causing the formation of a blood clot within the artery. These clots also grow until they block blood flow; this can cause a heart attack. New Penn research shows that clots forming under arterial-flow conditions have an unexpected ability to sense the surrounding blood moving over it.

The microfluidic device the research team used to observe the flow-dependent clotting behavior.
Credit: Image courtesy of University of Pennsylvania

The disease atherosclerosis involves the build up of fatty tissue within arterial walls, creating unstable structures known as plaques. These plaques grow until they burst, rupturing the wall and causing the formation of a blood clot within the artery. These clots also grow until they block blood flow; in the case of the coronary artery, this can cause a heart attack.

New research from the University of Pennsylvania has shown that clots forming under arterial-flow conditions have an unexpected ability to sense the surrounding blood moving over it.If the flow stops, the clot senses the decrease in flow and this triggers a contraction similar to that of a muscle. The contraction squeezes out water, making the clot denser.

Better understanding of the clotting dynamics that occur in atherosclerosis, as opposed to the dynamics at play in closing a wound, could lead to more effective drugs for heart-attack prevention.

The research was conducted by graduate student Ryan Muthard and Scott Diamond, professor and chair of the Department of Chemical and Biomolecular Engineering in the School of Engineering and Applied Science.

Their work was published in the journal Arteriosclerosis, Thrombosis and Vascular Biology, which is published by the American Heart Association.

"Researchers have known for decades that blood sitting in a test tube will clot and then contract to squeeze out water," Muthard said. "Yet clots observed inside injured mouse blood vessels don't display much contractile activity.We never knew how to reconcile these two studies, until an unexpected observation in the lab."

Using a specially designed microfluidic device, the researchers pulsed fluorescent dye across a clot to investigate how well it blocked bleeding. When they stopped the flow in order to adjust a valve to deliver the dye, the researchers were startled to see that a massive contraction was triggered in the clot. If they delivered the dye without stopping flow, there was no change in the clot properties.

"We think this may be one of the fundamental differences between clots formed inside blood vessels that cause thrombosis and clots formed when blood slowly pools around a leaking blood vessel during a bleeding event," Diamond said. "The flow sensing alters the clot mechanics."

To investigate this alteration, the researchers used an intracellular fluorescent dye that binds to calcium. They found that when the flow stops, the platelets' calcium levels increase and they become activated. By adding drugs that block ADP and thromboxane, chemicals involved in the clotting process, the researchers were able to prevent this platelet calcium mobilization and stop the contraction.

Millions of patients already take drugs that target these chemical pathways: P2Y12 inhibitors, such as Plavix, block ADP signaling in platelets, and aspirin blocks platelets' synthesis of thromboxane. This discovery suggests that these drugs may be interfering with contractile mechanisms that are triggered when ADP and thromboxane become elevated, such as when the flow around the clot decreases or stops.Beyond slowing the growth of clots, these anti-platelet drugs may also be altering the mechanics of the clot by preventing contraction.

"It is an example of 'quorum sensing' by the platelets in the clots," Diamond said. "The platelets are sensing each other and the prevailing environment. This causes them to release ADP and thromboxane, but it is rapidly diluted away by the surrounding blood flow.

"However, when the flow over the clot decreases or stops, the ADP and thromboxane levels rapidly build up, and this drives platelet contraction," Diamond said.


Story Source:

The above story is based on materials provided by University of Pennsylvania. Note: Materials may be edited for content and length.


Journal Reference:

  1. T. V. Colace, S. L. Diamond. Direct Observation of von Willebrand Factor Elongation and Fiber Formation on Collagen During Acute Whole Blood Exposure to Pathological Flow. Arteriosclerosis, Thrombosis, and Vascular Biology, 2012; DOI: 10.1161/ATVBAHA.112.300522

Cite This Page:

University of Pennsylvania. "New aspect of platelet behavior in heart attacks revealed: Clots can sense blood flow." ScienceDaily. ScienceDaily, 7 November 2012. <www.sciencedaily.com/releases/2012/11/121107200154.htm>.
University of Pennsylvania. (2012, November 7). New aspect of platelet behavior in heart attacks revealed: Clots can sense blood flow. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2012/11/121107200154.htm
University of Pennsylvania. "New aspect of platelet behavior in heart attacks revealed: Clots can sense blood flow." ScienceDaily. www.sciencedaily.com/releases/2012/11/121107200154.htm (accessed September 30, 2014).

Share This



More Health & Medicine News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How 'Yes Means Yes' Defines Sexual Assault

How 'Yes Means Yes' Defines Sexual Assault

Newsy (Sep. 29, 2014) Aimed at reducing sexual assaults on college campuses, California has adopted a new law changing the standard of consent for sexual activity. Video provided by Newsy
Powered by NewsLook.com
Scientists May Have Found An Early Sign Of Pancreatic Cancer

Scientists May Have Found An Early Sign Of Pancreatic Cancer

Newsy (Sep. 29, 2014) Researchers looked at 1,500 blood samples and determined people who developed pancreatic cancer had more branched chain amino acids. Video provided by Newsy
Powered by NewsLook.com
Colo. Doctors See Cluster of Enterovirus Cases

Colo. Doctors See Cluster of Enterovirus Cases

AP (Sep. 29, 2014) Doctors at the Children's Hospital of Colorado say they have treated over 4,000 children with serious respiratory illnesses since August. Nine of the patients have shown distinct neurological symptoms, including limb weakness. (Sept. 29) Video provided by AP
Powered by NewsLook.com
Dr.'s Unsure of Cause of Fast-Spreading Virus

Dr.'s Unsure of Cause of Fast-Spreading Virus

AP (Sep. 29, 2014) Doctors at the Children's Hospital of Colorado say they have treated over 4,000 children with serious respiratory illnesses since August. Nine of the patients have shown distinct neurological symptoms, including limb weakness. (Sept. 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins