Aug 07, 2002
By Pooja Vig
SINGAPORE (Reuters Health)
A Singapore-Australia joint venture, ES Cell International, and one of its collaborative partners, the National University of Singapore (NUS), announced the world's first published report of a human embryonic stem cell line grown entirely without exposure to mouse cells or other non-human ingredients.
The research is due to be published in the September 2002 edition of Nature Biotechnology.
Stem cells are immature cells capable of developing, or differentiating, into a number of different types of body cells. They offer promise for treating diseases in which a person's own cells have deteriorated, such as Alzheimer's disease, Parkinson's disease and many more.
The standard technique for creating human embryonic stem cell lines has been to extract cells from an embryo and grow them atop embryonic mouse cells, known as "feeder" cells, which excrete nutritional or growth factors that sustain the cell lines. But this close association with mouse cells raises safety questions, as the cell lines could transfer animal viruses to people.
In fact, all 78 stem cell lines listed on the National Institutes of Health Stem Cell Registry have been mixed in the laboratory with mouse cells, making them xenotransplant products. This could create substantial hurdles to US Food and Drug Administration (FDA) approval for clinical trials based on these cells.
Professor Ariff Bongso, who spearheaded the research at NUS, told Reuters Health that the team's early work on isolating embryonic stem cells in 1994 used human feeder cells derived from fallopian tubes. When the scientists could not sustain the cell lines for more than two generations, they thought the feeder cells were the problem, and so they started using mouse feeder cells.
"This has bothered me all these years because I did not believe the problem was with the feeder cells," said Bongso.
"Our recent experiments show that the feeder cells are not the issue," Bongso explained. "Embryonic stem cells are social cells that work best in a community -- in the past, we grew individual cells but our latest work shows that if we maintain clusters of cells, they survive well regardless of the feeder cells they are grown on.
"We have created a new cell line in a totally animal-free system and maintained it for 50 generations without differentiation," said Bongso.
This work, which has taken the team 20 months to complete, demonstrates that embryonic stem cells can successfully be grown on human feeder cells -- adult skin cells, at that. This bypasses any controversy about where these feeder cells may come from -- and has also created a complete system in which no animal ingredients are used to culture the cells.
ES Cell, which funded the research, has filed patents for the system, the world's first of its kind. The company plans to refine the process and then begin creating new cell lines that are completely animal-free. "We expect this to be the next gold standard in stem cells," Bongso said.
"We plan to make these new cell lines commercially available in the future -- in our opinion, this is the best thing we can do for our company and for this young area of research," Robert Klupacs, CEO of ES Cell International, told Reuters Health.
From a commercial perspective, the development of these cell lines using the new technology means that ES Cell International has overcome a significant obstacle to using embryonic stem cells in clinical trials. The company is looking into using embryonic stem cells for cancer treatment under the direction of Dr. Alan Colman, who recently joined the company from PPL Therapeutics PLC.
This does raise the question of the usefulness of the cell lines already approved for US federal funding; commercially available cell lines could, in the future, be more likely to meet FDA standards than the cell lines approved by the Bush administration.
On The Net:
ES Cell International: http://www.escellinternational.com/
© 2002 Reuters Ltd