(SG)'Clean' human stem cells grown

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http://www.newscientist.com/news/news.jsp?id=ns99992631

 

'Clean' human stem cells grown

 

19:00 04 August 02

 

NewScientist.com news service

 

Embryonic stem cells that are free from the risk of

animal pathogens have been grown by scientists in

Singapore. The technique overcomes a key stumbling

block to using ESCs to cure diseases like Parkinson's

or diabetes.

 

The therapeutic promise of ESCs depends on their

ability to develop into any different type of cell.

But they are notoriously difficult to grow in the lab,

not least because they must first be persuaded to

divide to produce more cells, without specialising.

 

Until now, biologists have done this by growing ESCs

with cells from mouse fetuses, and often with cow

serum as well. But this raised concerns that animal

pathogens could infect humans if the ESCs were ever

used in a patient.

 

Researchers fear that animal pathogens could cause

serious diseases in humans. For instance, HIV is

thought to have originated in chimpanzees.

 

Cells and serum

 

Ariff Bongso's team at the National University of

Singapore successfully replaced the mouse cells and

cow serum with muscle cells from human fetuses and

human serum. The cells and serum were screened for

HIV-1, HIV-2 and for hepatitis B.

 

" No one in their right mind commercially would try and

develop a cell product that was xeno-derived, " says

Chris Juttner, medical director at BresaGen, an

Adelaide-based stem cell company. " If they truly have

derived cell lines that are pathogen-free, every one

will be trying to repeat it. "

 

The ESCs produced by Bongso's team look and behave

just like ESCs grown using mouse cells. For instance,

when the researchers injected the cells into mice with

severely depressed immune systems, they formed tumours

called teratomas, which contain cells from each of the

three main classes of tissue. Teratoma formation is a

classic test for ESCs.

 

 

Further hurdles

 

 

Bongso's team is getting guidance from experts at the

US Food and Drug Administration to help them develop

cell lines that stand the best chance of being

approved for medical use when and if stem cell therapy

is shown to work in humans. For example, they will try

to improve safety even more by screening cells for

other human diseases such as CJD.

 

They are also trying to grow ESCs using adult muscle

and skin cells as an alternative to fetal muscle

cells, because of ethical issues. The results are

" very promising, " says Bongso.

 

But there are still many hurdles to overcome before

stem cell therapy becomes a reality, researchers warn.

These include ensuring implanted cells cannot cause

cancers and finding ways to churn out the large

numbers of the different cell types that would be

needed for transplants.

 

And the US government will only support research on

the 78 cell lines that existed prior to August 9, 2001

- all of which were grown with animal cells and could

therefore theoretically contain animal pathogens.

 

Journal reference: Nature Biotechnology

(DOI:10.1038/nbt726)

 

Rachel Nowak, Melbourne

 

 

 

 

 

 

 

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