A new type of stem cell isolated from human bone marrow could have all the medical potential of embryonic stem cells (ES cells), US researchers say. However, not all scientists are convinced of that the cells are as versatile as they appear to be, according to a report in the Washington Post. The new study, published in the Journal of Clinical Investigation, builds on earlier studies which suggest that adult bone marrow cells can help repair other body tissues, such as heart and liver.
Scientists based at Tufts University in Boston used cell sorting machines to isolate the new cells from bone marrow donated by three different individuals. When injected into the hearts of rats that had experienced heart attacks, some of the bone marrow-derived cells became new heart cells, whilst others turned into new blood vessels. Further experiments showed that the cells could turn into nerve-like cells in the laboratory, suggesting that they could be capable of growing into many different cell types.
ES cells are the body's 'master cells', capable of developing into any kind of body tissue. Many scientists are hoping to develop new ES cell-based therapies for a range of different diseases in which a particular cell type is lost or damaged. However, ES cell research has triggered controversy in many countries, including the US, since it involves the destruction of embryos. This has lead several groups to look for alternative cells that have the same properties as ES cells. Team leader Douglas Losordo says of the latest study: 'I think embryonic stem cells are going to fade into the rearview mirror of adult stem cells', adding that bone marrow 'is like a repair kit. Nature provided us with these tools to repair organ damage'.
However, several other scientists, while praising the study, think it is too early to halt research into any type of stem cell. James Battey, head of the stem cell program at the National Institutes of Health, called the study 'very impressive, very interesting and I think very significant'. But he stressed that 'we're very early in the game and I can't say the results are absolutely airtight'. Battey added that 'we'd like to see this type of stem cell and other bone marrow stem cells and research on human embryonic stem cells move forward'. Stem cell researcher John Gearhart also cautioned that 'the contention that we have no need for embryonic stem cells is a very premature statement'.
In January 2002, Caroline Verfaille of the University of Minnesota, reported the discovery of multipotent adult progenitor cells (MAPCs) - apparently capable of giving rise to all tissues in the body, just like ES cells. Also, in June 2002, a team of US researchers, again led by Catherine Verfaille showed that a type of adult stem cell derived from bone marrow (mesenchymal cells or MSCs) has many of the same characteristics as ES cells. A later report suggested that MAPCs and MSCs might actually be the same type of cell. Verfaille told the Washington Post that she was not sure that Losordo's cells are different from hers. 'In a lot of respects these cells 'smell' very much like the cells we've described in the past', she said.