Featured Research

from universities, journals, and other organizations

Immune Cells From Spleen May Be Essential In Healing Heart Attack Damage, Mouse Study Indicates

Date:
July 31, 2009
Source:
Massachusetts General Hospital
Summary:
Researchers have discovered an unexpected reservoir of monocytes in the spleen and found that these cells are essential to recovery of cardiac tissue in an animal heart attack model.

It takes a spleen to mend a broken heart – that's the conclusion of a surprising new report from researchers at the Massachusetts General Hospital (MGH) Center for Systems Biology, directed by Ralph Weissleder, MD, PhD. In the July 31 issue of Science the team reports how, in following up an intriguing observation, they discovered an unexpected reservoir of the immune cells called monocytes in the spleen and went on to show that these cells are essential to recovery of cardiac tissue in an animal heart attack model.

Related Articles


"Monocytes are known to serve as a central defense system against injury, and we found that monocytes released from the spleen go directly to the injured heart and participate in wound healing," says Matthias Nahrendorf, MD, PhD, a co-lead author of the study.

Monocytes are generated in the bone marrow, released into the blood and are known to accumulate at injured or infected tissues, where they differentiate into macrophages or dendritic cells. In investigating processes involved in the healing of ischemic heart tissue – the sort of injury produced in a heart attack – in mice, the research team was surprised to find more monocytes accumulating at the site of injury than would be found in the animals' entire circulatory system. When they searched many types of tissue for the presence of cells with monocyte-specific molecules, they only found significant numbers of such cells in the spleen.

Monocytes in the spleen were identical in appearance, composition and function to monocytes in the blood. To investigate the splenic monocyte reservoir's potential involvement in cardiac healing, the researchers used several new technologies. A newly developed microscopic technique allowed them to determine how and where monocytes are stored in the spleen – previously known to store red blood cells – and to study how monocytes are released in response to an experimentally-induced heart attack. A novel three-dimensional optical imaging technique (fluorescence molecular tomography, developed at the MGH Center for Molecular Imaging Research) allowed study of monocyte-mediated immune functions at the site of heart muscle injury.

In mice whose spleens were removed and replaced with a donor organ, an induced heart attack led to rapid increase of spleen-derived donor monocytes in the bloodstream and massive accumulation of donor cells at the site of injury. In animals from whom spleens were removed but not replaced, heart attack produced no significant monocyte increase in the bloodstream or in the heart. "With all these approaches together, we found that the monocytes that travel to the heart after a heart attack come directly from the spleen and that, without the splenic monocytes, the heart tissue does not heal well," says Filip Swirski, PhD, co-lead author of the Science report.

The investigators also found that the hormone angiotensin II, known to be released in response to a heart attack, is actively involved in the release of monocytes from the spleen. Identifying that pathway could lead to ways of manipulating the splenic monocyte reservoir to improve healing after a heart attack and potentially regulate other inflammatory situations. "We need to know whether this monocyte reservoir is important in other diseases – such as viral or bacterial infection, cancer or atherosclerosis – and understand how to precisely control storage and release of monocytes in a therapeutic setting, both of which we are currently investigating," says Mikael Pittet, PhD, senior author of the Science report.

Pittet and Nahrendorf are both assistant professors of Radiology at Harvard Medical School, and Swirski is an instructor in Radiology. Additional co-authors of the Science report are Martin Etzrodt, Moritz Wildgruber, Virna Cortez-Retamozo, Peter Panizzi, PhD, Jose-Luiz Figueiredo, MD, Rainer Kohler, PhD, Aleksey Chudnovskiy, Peter Waterman, Elena Aikawa, MD, PhD, Thorsten Mempel, MD, PhD, and Ralph Weissleder, MD, PhD, MGH Center for Systems Biology; and Peter Libby, MD, Brigham and Women's Hospital. The study was supported by grants from the National Institutes of Health and the MGH Center for Systems Biology.


Story Source:

The above story is based on materials provided by Massachusetts General Hospital. Note: Materials may be edited for content and length.


Cite This Page:

Massachusetts General Hospital. "Immune Cells From Spleen May Be Essential In Healing Heart Attack Damage, Mouse Study Indicates." ScienceDaily. ScienceDaily, 31 July 2009. <www.sciencedaily.com/releases/2009/07/090730141557.htm>.
Massachusetts General Hospital. (2009, July 31). Immune Cells From Spleen May Be Essential In Healing Heart Attack Damage, Mouse Study Indicates. ScienceDaily. Retrieved November 22, 2014 from www.sciencedaily.com/releases/2009/07/090730141557.htm
Massachusetts General Hospital. "Immune Cells From Spleen May Be Essential In Healing Heart Attack Damage, Mouse Study Indicates." ScienceDaily. www.sciencedaily.com/releases/2009/07/090730141557.htm (accessed November 22, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Saturday, November 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

WFP: Ebola Risks Heightened Among Women Throughout Africa

WFP: Ebola Risks Heightened Among Women Throughout Africa

AFP (Nov. 21, 2014) Having children has always been a frightening prospect in Sierra Leone, the world's most dangerous place to give birth, but Ebola has presented an alarming new threat for expectant mothers. Duration: 00:37 Video provided by AFP
Powered by NewsLook.com
Could Your Genes Be The Reason You're Single?

Could Your Genes Be The Reason You're Single?

Newsy (Nov. 21, 2014) Researchers in Beijing discovered a gene called 5-HTA1, and carriers are reportedly 20 percent more likely to be single. Video provided by Newsy
Powered by NewsLook.com
Milestone Birthdays Can Bring Existential Crisis, Study Says

Milestone Birthdays Can Bring Existential Crisis, Study Says

Newsy (Nov. 21, 2014) Researchers find that as people approach new decades in their lives they make bigger life decisions. Video provided by Newsy
Powered by NewsLook.com
Ebola: Life Without School in Guinea

Ebola: Life Without School in Guinea

AFP (Nov. 21, 2014) Following the closure of schools and universities in Guinea because of the Ebola virus, students look for temporary work or gather in makeshift classrooms to catch up on their syllabus. Duration: 02:14 Video provided by AFP
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