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Questions over stem cell findings

7 April 2003
By BioNews
Appeared in BioNews 202

Adult stem cells from bone marrow may be fusing with other types of body tissue, rather than replacing them, two new US studies suggest. The research, published in Nature, shows that in mice, liver damage can be repaired using transplanted bone marrow stem cells. But it seems that the stem cells are fusing with existing damaged cells, rather than turning into new liver cells, as was previously believed. There is now serious concern over whether these earlier studies 'reflected reality', says lead researcher Markus Grompe, of Oregon Health and Sciences University in Portland. However, another recent study of cheek cells derived from transplanted bone marrow cells shows no evidence of fusion.

Previous studies suggested that bone marrow stem cells, which normally make different types of blood cell, can also turn into liver, muscle and pancreas cells. These findings promise new treatments for a range of diseases, and offer an alternative to the use of 'master' stem cells obtained from early embryos. But Grompe says he's not convinced that bone marrow stem cells give rise to anything other than blood. His team found that damaged mouse livers were repaired following bone marrow transplants, but that the new liver cells contained two or three times the normal amount of DNA. This finding indicates that the donor bone marrow cells had fused with the recipient liver cells. In a separate study, a team from the University of Washington, Seattle, reported similar results. Grompe thinks that bone marrow cells can 'reprogramme' themselves as liver cells, and maybe other types of cell, by fusing with them.

But Eva Mezey, lead author of another stem cell study published recently, thinks that cell fusion could be peculiar to the liver. Her team, based at the National Institute of Neurological Disorders and Stroke in Maryland, US, studied cheek cells from female leukaemia patients who had received bone marrow transplants from men. They found that between two and 12 per cent of the women's cheek cells originated from the male transplanted cells, and that only 2 out of 9700 cells studied showed evidence of fusion.

Differentiation of human bone marrow-derived cells into buccal epithelialcells in vivo
The Lancet |  29 March 2003
Excess DNA prompts stem-cell rethink
Nature |  31 March 2003
Fusion claims rock stem cell research
New Scientist |  5 April 2003
16 December 2004 - by BioNews 
A clinical trial using bone marrow stem cells to treat irreversible liver damage has started in Japan, New Scientist magazine reports. Scientists at Yamaguchi University began the trial after showing that bone marrow stem cell transplants can partly reverse serious liver damage in mice. A similar trial using bone marrow...
25 March 2004 - by BioNews 
Two new studies have cast further doubt on the ability of blood stem cells to turn into heart cells, even though several clinical trials based on this promising new treatment are currently underway. Researchers at Stanford University, California, and the University of Washington in Seattle have failed to duplicate the...
20 October 2003 - by BioNews 
Adult bone marrow stem cells fuse with existing cells to grow new tissues, rather than transforming into other types of cell, two new studies suggest. Researchers at Stanford University have shown that transplanted bone marrow cells fuse with specialised brain cells involved in controlling movement and balance. A second study...
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