Usefulness of adult stem cells questioned

Two teams of scientists have published research that suggests that adult stem cells may not have the as much potential to develop into other kinds of body cell as was previously thought.

A team of researchers from the University of Florida, US, cultured stem cells taken from the bone marrow of adult mice in the same dish as embryonic stem cells. The scientists hoped that the adult cells would be altered in some way by the embryonic cells and would revert to a more 'primitive' state. They found that a new type of cell, that showed many of the characteristics of an embryonic stem cell, was formed and believed that the experiment had been successful.

However, when the new cells were examined, it was found that some of the adult stem cells had fused with the embryonic stem cells, resulting in cells with double the amount of chromosomes ordinarily present. The new cells were coaxed to develop into nerve, muscle and other types of cell.

A second team of scientists, based at the University of Edinburgh, Scotland, conducted a similar experiment using stem cells taken from the brains of adult mice. Austin Smith, leader of the Edinburgh research team, said that the research 'suggests a need for caution with regard to the therapeutic use of adult-tissue stem cells', adding 'If they only make other tissues by fusing with existing cells rather than by producing new cells, their utility for tissue repair and regenerative medicine will be greatly restricted'. Naohiro Terada, lead author of the Florida study, said that more experiments would have to take place 'before concluding that adult stem cells have real pluripotency or not'.