Featured Research

from universities, journals, and other organizations

Jefferson Scientists Develop Method To Isolate Blood Stem Cells, The Lifetime Source Of All Blood Cells

Date:
September 8, 1999
Source:
Jefferson Medical College
Summary:
Scientists at Jefferson Medical College have found a way to isolate hard-to-find hematopoietic stem cells. The researchers, in identifying a chemical beacon – a protein marker – on the cell, believe the new work will lead to laboratory production of all types of blood cells for transfusions and innovative approaches for bone marrow transplants and gene therapy.

The work could lead to laboratory production of blood cells for transfusions and to clinical innovations in bone marrow transplants and gene therapy

Scientists at Jefferson Medical College have found a way to isolate hard-to-find hematopoietic stem cells. The researchers, in identifying a chemical beacon – a protein marker – on the cell, believe the new work will lead to laboratory production of all types of blood cells for transfusions and innovative approaches for bone marrow transplants and gene therapy.

"The hematopoietic stem cell has been considered the elusive Holy Grail of hematology and immunology," says Cesare Peschle, M.D., professor of microbiology and immunology at Thomas Jefferson University, who led the work. "Now it has been found and captured by identifying the first specific and functional stem cell marker."

Dr. Peschle, who is also Chairman of the Department of Hematology-Oncology at Istituto Superiore di Sanita in Rome, and his co-workers at Jefferson’s Kimmel Cancer Center, and in Italy, Germany, and at the University of Nevada report their work September 3 in the journal Science.

Hematopoietic stem cells, created by bone marrow, have the two unique abilities: to develop into any kind of blood cell and to self-renew by generating new daughter stem cells. Yet they are very rare, making up only 1 in 100,000 marrow cells. They have been notoriously difficult to distinguish from the blood’s other progenitor cells, which are further along in the differentiation process.

"We have for the first time a marker – KDR – which seems to be specific for the hematopoietic stem cell as compared to other primitive hematopoietic cells," Dr. Peschle says.

"The use of the stem cell is very important and broad," Dr. Peschle says. "Having the stem cell purified, we have the possibility finally of characterizing it at a functional, phenotypic and molecular level." Scientists can also learn to manipulate the cell in the laboratory, he says, and "will induce the stem cell to do in the laboratory what it does in the body – self-renew and differentiate to generate a huge number of red blood cells, white blood cells and platelets." Scientists then can generate in the laboratory the circulating blood cells required for blood transfusions, which currently are obtained by transfusions from normal donors.

For years, researchers have had tremendous difficulty distinguishing between two types of precursor blood cells: Hematopoietic progenitor and stem cells. Progenitor cells are immature cells that can differentiate into red blood cells, white blood cells and platelets. They are used to restore patients’ blood and immune systems after high-dose chemotherapy or radiation for cancer. Stem cells are earlier cells which have the unique capacity to self-perpetuate. They generate progenitor cells and blood cells throughout life. Progenitors have no self-renewal capacity – they only give rise to more differentiated precursor cells.

Scientists can isolate undifferentiated progenitor cells using a marker on the cell known as CD34. This methodology was pioneered by Dr. Peschle and co-workers in a report in Science in 1990. But identifying hematopoietic stem cells has been more difficult, explains Dr. Peschle. Hematopoietic progenitor cells are rare – between .5 and 1 percent of bone marrow cells are progenitors carrying CD34. Yet, stem cells are even less frequent, perhaps .1 percent of CD34 cells, or 1 stem cell in 100,000 marrow cells.

The problem was that there was no specific marker on the cell surface of stem cells comparable to CD34 on progenitor cells. "Once you have a marker protein for hematopoietic stem cells," Dr. Peschle explains, "you can theoretically raise antibodies against the marker, and then you can separate stem cells from other cell populations."

They focused on KDR, a protein that functions as a receptor for the vascular endothelial growth factor, or VEGF. KDR is expressed on endothelial cells. The scientists found that it is also expressed at low levels on CD34-positive progenitor cells. In embryonic life, primitive hematopoietic cells are made in close contact with KDR-positive endothelial cells. They argued that KDR may represent a marker for hematopoietic stem cells after birth.

They found an antibody that recognized the KDR receptor and which could isolate the KDR-expressing cells from the other progenitors in the CD34-positive progenitor population. Those cells with KDR comprised all of the hematopoietic stem cells and no progenitor cells. In contrast, the great majority of CD34 cells lacking KDR contained no stem cells and all progenitors.

Now, Dr. Peschle says, he and his co-workers have precisely evaluated the capability of KDR-positive stem cells to repopulate the bone marrow with blood cells in transplanted animals. They can also determine the exact frequency of stem cells in the KDR-positive population.

Dr. Peschle believes that the ability to eventually harness the hematopoietic stem cell in both the laboratory and clinic will someday help alleviate blood shortages for transfusions and to develop innovative approaches to bone marrow transplants (such as in solid tumor patients, by purging the transplanted stem cells from tumor cells) and gene therapy. In AIDS patients, for example, anti-HIV sequences could be inserted in isolated stem cells.

For more information, please call 1-800-JEFF NOW.


Story Source:

The above story is based on materials provided by Jefferson Medical College. Note: Materials may be edited for content and length.


Cite This Page:

Jefferson Medical College. "Jefferson Scientists Develop Method To Isolate Blood Stem Cells, The Lifetime Source Of All Blood Cells." ScienceDaily. ScienceDaily, 8 September 1999. <www.sciencedaily.com/releases/1999/09/990908075857.htm>.
Jefferson Medical College. (1999, September 8). Jefferson Scientists Develop Method To Isolate Blood Stem Cells, The Lifetime Source Of All Blood Cells. ScienceDaily. Retrieved September 21, 2014 from www.sciencedaily.com/releases/1999/09/990908075857.htm
Jefferson Medical College. "Jefferson Scientists Develop Method To Isolate Blood Stem Cells, The Lifetime Source Of All Blood Cells." ScienceDaily. www.sciencedaily.com/releases/1999/09/990908075857.htm (accessed September 21, 2014).

Share This



More Health & Medicine News

Sunday, September 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Sierra Leone's Nationwide Ebola Curfew Underway

Sierra Leone's Nationwide Ebola Curfew Underway

Newsy (Sep. 20, 2014) Sierra Leone is locked down as aid workers and volunteers look for new cases of Ebola. Video provided by Newsy
Powered by NewsLook.com
Changes Found In Brain After One Dose Of Antidepressants

Changes Found In Brain After One Dose Of Antidepressants

Newsy (Sep. 19, 2014) A study suggest antidepressants can kick in much sooner than previously thought. Video provided by Newsy
Powered by NewsLook.com
Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) 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:
from the past week

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