X-Message-Number: 27245
Date: 19 Oct 2005 13:57:13 -0700
From: 
Subject: [News] NanoAging.com News

New University Of Toronto Strategy Will Boost Cord Blood Stem Cells



A team of bioengineers led by the University of Toronto has discovered a way to 
increase the yield of stem cells from umbilical cord blood, to an extent which 
could broaden therapeutic use of these cells.


In a paper published in the October issue of Experimental Hematology, 
researchers working in the University of Toronto''s Stem Cell Bioengineering 
Laboratory have identified an important component blocking the growth of stem 
cells. U of T scientists discovered stem cells in 1961, and for about two 
decades researchers around the world have been searching for a way to expand the
number of stem cells harvested from umbilical cord blood, which can be used 
instead of bone marrow for transplantation into patients with blood cancers. <br
/>
<br />

"It''s been very hard to grow blood stem cells at all," says Professor Peter W. 
Zandstra of the University of Toronto''s Institute of Biomaterials and 
Biomedical Engineering, and head of the laboratory in which the research was 
conducted. "We''ve tried to understand how those cells talk to each other, and 
by controlling that, trying to get the ones we want to grow better." <br />
<br />

In any culture, blood stem cells are very rare, Zandstra explains: typically 
less than one in 100 cells. "If you want to grow that one cell among the other 
cells that are more aggressive, you have to target that cell." <br />
<br />

The research team developed a way to remove the non-stem cells -- differentiated
cells, or "lineage-positive" cells -- to create an environment that allows stem
cells to grow better. "A mature [lineage-positive] cell expresses markers of 
differentiated lineages, and a stem cell is typically negative for these 
markers," Zandstra says. "So we removed the lineage-positive cells. They secrete
molecules, or cytokines, which inhibit growth of stem cells. So, by removing 
them, we''re making the environment better for stem cells." <br />
<br />

Typically, the umbilical cord does not yield a large volume of stem cells -- 
perhaps enough to treat a child, but rarely an adult. The new research findings 
may allow new cord-blood stem cells to be developed in the laboratory -- enough 
to treat adult patients as well as children. The major use of blood stem cells 
is for transplantation into patients with leukemia and other blood-borne 
cancers. <br />
<br />

>From their studies in mice, the researchers know that new stem cells obtained 
through their expansion technology can engraft in bone marrow and maintain 
special properties such as the ability to migrate in the body. <br />
<br />

The researchers have further refined their system by developing a "bioreactor" 
-- a vessel in which to grow the stem cells in a closed and controlled 
environment, away from environmental contaminants. <br />
<br />

"The hope is that very soon, if the results are the same with the bioreactor as 
they were with our experiments to date, we will move to clinical trials," says 
Zandstra -- ideally within the next year.

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