Featured Research

from universities, journals, and other organizations

Blood Stem Cells Originate And Are Nurtured In The Placenta

Date:
March 6, 2008
Source:
University of California - Los Angeles
Summary:
Solving a long-standing biological mystery, stem cell researchers have discovered that blood stem cells, the cells that later differentiate into all the cells in the blood supply, originate and are nurtured in the placenta.

Solving a long-standing biological mystery, UCLA stem cell researchers have discovered that blood stem cells, the cells that later differentiate into all the cells in the blood supply, originate and are nurtured in the placenta.

Related Articles


The discovery may allow researchers to mimic the specific embryonic microenvironment necessary for development of blood stem cells in cell culture and grow them for use in treating diseases like leukemia and aplastic anemia, said Dr. Hanna Mikkola, a researcher in the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research and senior author of the study.

“It was a big mystery, where these cells originated,” said Mikkola, an assistant professor of molecular, cell and developmental biology. “This is the first time we can really say definitively that blood stem cells are generated in the placenta. There’s no more speculation.”

The study is published March 6, 2008 in the journal Cell Stem Cell. Researchers in Mikkola’s lab are working now to replicate this work, done in mouse models, in humans.

“If we want to fully harness the potential of embryonic stem cells to treat disease, it’s critical for us to learn how to make tissue specific stem cells,” said Mikkola, who also is a researcher at UCLA’s Jonsson Comprehensive Cancer Center. “We can learn that by studying what happens during embryonic development.”

Scientists now can take embryonic stem cells, the cells that can become any tissue type in the body, and coax them into becoming all the cells in the blood supply, such as red and white blood cells and platelets. However, they can’t make blood stem cells that self-new, or make more of themselves, and don’t differentiate prematurely when transplanted into patients.

The only way this currently can be achieved is by manipulating the cell’s nuclear regulatory machinery with genes using retroviruses. To generate blood stem cells that are safe for use in patients, it is imperative that scientists learn how to generate self-renewing blood stem cells in a more natural way, by providing the correct developmental cues from the environment in which the cells develop.

Currently, patients with certain types of leukemia have one shot at a cure – a bone marrow transplant. However, there aren’t nearly enough bone marrow donors to provide patients with perfect matches. Use of a less than perfect donor match carries a risk of graft vs. host disease, in which the immune cells from the donated marrow attack the body of the transplant patient. Cord blood contains blood stem cells, but not in large enough quantities to transplant an adult patient, Mikkola said.

If researchers could grow blood stem cells, those cells could be transplanted into these patients. The blood stem cells would then differentiate into a new, and healthy, blood supply. And with the recent success in creating induced pluripotent stem cells (iPS) from human skin cells, a patient’s own skin cells could perhaps be used to create iPS cells. Those cells could then be transformed into blood stem cells, creating an immune-compatible source of blood supply that eliminates the risk of graft vs. host disease.

In her previous research, Mikkola and collaborators in Harvard and France had discovered that the placenta contained a large pool of blood stem cells, but it wasn’t clear if they originated elsewhere and migrated to the placenta to self-renew. Using a unique mouse model, a mouse embryo without a heartbeat, Mikkola and her team were able to find the blood stem cells at the site of their origin because there was no circulation of blood through the body.

“Using this model, we identified that the placenta has the potential to make hematopoietic (blood) stem cells with full differentiation ability to create all the major lineages of blood cells,” Mikkola said. “The placenta acts as a sort of kindergarten for these newly made blood stem cells, giving them the first education they need.”

It was previously known that blood stem cells could be found in the dorsal aorta, but there were so few located there that scientists reasoned it could not be the sole source of blood stem cells in the embryo. Mikkola’s discovery indicates that the blood stem cells are generated in the large arteries of the embryo and placenta, and then move to a specific site, or niche, where they expand and mature.

This recent study indicates that the first niche for expansion of blood stem cells is the placenta’s vascular labyrinth, where oxygen and nutrients are exchanged between the mother and the fetus. The findings show the placenta harbors two different microenvironments, one area where blood stem cells originate and another area, the labyrinth, that nurtures them, allowing them to expand in number.

These niches serve different roles and could provide clues to researchers seeking to grow blood stem cells. Mikkola now is seeking to uncover the critical biological signals and cues during embryonic development that drive blood stem cell generation and expansion and keep the cells from differentiating prematurely.

“The labyrinth is a source of many growth factors and cytokines,” Mikkola said. “We just need to identify what those signaling molecules and cues are that are nurturing those cells when in the placenta.”

Mikkola is confident the study can be confirmed in humans. “Everything we’re learning suggests we will find the same thing in the human placenta,” she said.


Story Source:

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


Cite This Page:

University of California - Los Angeles. "Blood Stem Cells Originate And Are Nurtured In The Placenta." ScienceDaily. ScienceDaily, 6 March 2008. <www.sciencedaily.com/releases/2008/03/080305121006.htm>.
University of California - Los Angeles. (2008, March 6). Blood Stem Cells Originate And Are Nurtured In The Placenta. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2008/03/080305121006.htm
University of California - Los Angeles. "Blood Stem Cells Originate And Are Nurtured In The Placenta." ScienceDaily. www.sciencedaily.com/releases/2008/03/080305121006.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Kids Die While Under Protective Services

Kids Die While Under Protective Services

AP (Dec. 18, 2014) As part of a six-month investigation of child maltreatment deaths, the AP found that hundreds of deaths from horrific abuse and neglect could have been prevented. AP's Haven Daley reports. (Dec. 18) Video provided by AP
Powered by NewsLook.com
Dads-To-Be Also Experience Hormone Changes During Pregnancy

Dads-To-Be Also Experience Hormone Changes During Pregnancy

Newsy (Dec. 18, 2014) A study from University of Michigan researchers found that expectant fathers see a decrease in testosterone as the baby's birth draws near. Video provided by Newsy
Powered by NewsLook.com
Prenatal Exposure To Pollution Might Increase Autism Risk

Prenatal Exposure To Pollution Might Increase Autism Risk

Newsy (Dec. 18, 2014) Harvard researchers found children whose mothers were exposed to high pollution levels in the third trimester were twice as likely to develop autism. Video provided by Newsy
Powered by NewsLook.com
UN: Up to One Million Facing Hunger in Ebola-Hit Countries

UN: Up to One Million Facing Hunger in Ebola-Hit Countries

AFP (Dec. 17, 2014) Border closures, quarantines and crop losses in West African nations battling the Ebola virus could lead to as many as one million people going hungry, UN food agencies said on Wednesday. Duration: 00:52 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