The search for stem cells may prove as elusive as earlier scientific searches for substances such as phlogiston, an expert has claimed.
Although phlogiston does not exist, the concept of a single chemical being responsible for fire led to major breakthroughs in chemistry and the discovery of oxygen.
According to Professor Arthur Lander, of the Center for Complex Biological Systems at the University of California, Irvine, USA, scientists are struggling to identify cells that are distinctively and uniquely stem cells.
But, he says, the search for stem cells is still leading to biological breakthroughs.
Writing in the Journal of Biology, he says: "It is curious that, after 45 years, we are unable to place the notion of ‘stemness’ on a purely molecular footing. Of course, the fact that a goal has not been achieved after a long time does not mean that the answer is not around the corner.
"But it does give one cause to wonder whether something we are doing needs to change, either in the question we are asking or the way we are approaching it."
Professor Lander argues that ordinary cells may be able to take on the role of stem cells, as part of biological systems. This would make efforts to identify and target stem cells to treat cancer unsuccessful.
He adds: "If feedback and lineage progression continue to take place in cancerous tissues, we might observe that under different conditions – different stages of tumorigensis, different parts of a tumour, different amounts of tumour cells – that different cell types will assume the role of cancer stem cell.
"Like phlogiston, the term ‘stem cell’ is a scientific concept. Just as investigating the concept of phlogiston allowed the discovery of oxygen and the process of oxidation, it may be that by refashioning our thinking about stem cells ? with systems relationships and dynamics taking the place of molecular signatures and simple gene regulatory circuits – the concept of stemness will continue to light the path toward understanding."
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