The stem cell revolution is not what you suppose it’s

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Michelle D’urbano

AT THE turn of the 21st century, stem cells – the master builders of the body – took hold of our collective imagination. We began to dream of their marvellous healing powers. The era of “regenerative medicine” seemed to be dawning. Soon, we would be using stem cells to repair and replace damaged hearts, joints, spinal cords, kidneys, livers, windpipes, eyes and more. You name it, stem cells would fix it.

More than 20 years have passed and we are still waiting. Despite the great promise of stem cell research and the hard work of scientists worldwide, the dream of regenerative medicine remains just that – a dream. If this sounds surprising, perhaps it is because you have heard about stem cell clinics offering treatments directly to consumers for all kinds of conditions: AIDS, Alzheimer’s, arthritis and even covid-19. However, these are unproven therapies. Rigorous clinical trials haven’t generally established their effectiveness, and there are still safety concerns.

Yet business is booming for those selling unproven stem cell treatments, with a global turnover of an estimated $2.4 billion annually. In their hands, stem cells become snake oil, and stem cell research a pseudoscience.

So far, there is only one tried-and-true stem cell therapy available: bone marrow transplantation and its variants, all of which involve the use of blood stem cells to restore someone’s blood-making capacities. Pioneered in the 1950s by researchers like Don Thomas (who won a Nobel prize for his efforts), this method has been routinely used since the 1980s to treat conditions like leukaemia. Over 1.5 million blood stem cell transplants have been performed globally, with most recipients seeing significant benefits in the length and quality of their lives.

Bone marrow transplantation is certainly a form of regenerative medicine. However, it was developed long before stem cell fever took hold. The dream of regenerative medicine hinges on stem cells working other wonders. Over the years, hundreds of thousands of scientific articles have explored this possibility, but without much success.

The chief exception is the approved use of mesenchymal stromal cells (which some scientists regard as stem cells) to treat immune disorders like Crohn’s disease and graft-versus-host disease. While this is a fertile field of research, it isn’t regenerative medicine. The transplanted mesenchymal cells aren’t expected to restore damaged tissues and organs, merely to release useful chemicals.

Still, there is no reason to despair. The fact that regenerative medicine hasn’t yet lived up to its promise doesn’t mean it never will. As the history of medicine shows, good things take time and effort. Bone marrow transplantation is a case in point.

Make no mistake, stem cell research is thriving. It has taught us a great deal about how the body works and how to treat disease.

Especially exciting is the recent invention of “organoids“. These are cultured from stem cells and usually combine several different cell types, which spontaneously form themselves into miniature organs, such as mini-brains or hearts. Organoids provide us with a much better picture of what goes on in the body than a regular two-dimensional cell culture.

So if you want a stem cell revolution, look no further. Sure, it isn’t the one that we have all been dreaming of – and that stem cell charlatans have tried to hijack. But in one respect, it is infinitely better: it is real.

Although this is a lab-based revolution, its clinical implications are huge. Stem cells are speeding up the development of new drugs across the board, making it easier to decide which ones to take to clinical trial and what side effects they are likely to have.

John E. J. Rasko is at Royal Prince Alfred Hospital, Sydney and Carl Power is at the University of Sydney. Their new book, Flesh Made New: The Unnatural History and Broken Promise of Stem Cells, is out now.

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