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Hopes rise after stem cell breakthrough

Alok Jha

All of the concerns about contaminating proteins in existing stem cell lines can essentially be removed using this medium

London: Scientists have created human stem cell cultures without using any animal cells for the first time.

The breakthrough will bring possible treatments for diseases such as diabetes, Alzheimer's and Parkinson's a step closer.

Growing cells outside the body needs a carefully controlled environment.

Typically, the mix of nutrients, growth factors and blood serum used to keep the cells healthy is derived from animals — in the case of human embryonic stem cells, the materials come from mouse embryos.

Inherent problems

Some scientists argue that this method of growing cells has inherent problems: viruses from the animal cells, for example, may be taken up by the human cells and could infect patients.

``All of the concerns about contaminating proteins in existing stem cell lines can essentially be removed using this medium,'' said Tenneille Ludwig, a University of Wisconsin-Madison scientist working at WiCell, the company which led the effort to develop the new culture medium. ``This work helps us clear some of the major hurdles for using these cells therapeutically.''

James Thomson, a professor of anatomy at the same university who was the first person to successfully grow human embryonic stem cells in the lab seven years ago, said there had been dramatic improvements in the way cells were grown in the lab in recent years.

``This is the first time it has been possible for us to derive new cell lines in completely defined conditions in a medium that completely lacks animal products,'' he said.

Professor Thomson said researchers had previously grown stem cell cultures without animal products, but those methods used poorly defined or proprietary products.

In early 2005, WiCell scientists reported that they were able to culture stem cells in the absence of mouse cells, the most commonly used animal product in stem cell culture systems.

The new work in effect removes remaining animal products such as bovine serum and replaces them with products of human origin in a recipe that is completely defined. The two new Wisconsin stem cell lines have survived for more than seven months in the new culture medium.

The authors of the study add that the new technique could open up the stem cell debate in the U.S.: ``Derivation and culture in serum-free, animal product-free, feeder-independent conditions mean that new human [embryonic stem] cell lines could be qualitatively different from the original lines, and makes current public policy in the United States increasingly unsound.''

No access

U.S. researchers have no access to federal funding for work on stem cells created after 2001, a policy which will be debated in the Senate early this year. Scientists have called for a relaxation of the rules because existing stem cell lines have been shown to accumulate genetic mutations.

While these mutations pose no serious threat to research, they could stop the cells being used for therapies. —

© Guardian Newspapers Limited 2004

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