For bold investors, their claimed scientific coup, made under the auspices of a company called TriStem, could earn prodigious fortunes for themselves and their backers. But if they are wrong, they will not only lose their shirts: they will have exposed what many scientists believe is fundamentally at fault in the epoch-making scientific field known as stem-cell research.

Stem cells are primitive living cells that can be artificially coaxed to grow into any type of specific cell or tissue in the body. Scientists are confident that stem cells will one day deliver cures for virtually any kind of organ, blood or tissue dysfunction. Stem cells are tantamount to medicine's philosopher's stone – the mythical alchemical process that turned dross to gold – offering astounding new prospects for people afflicted by a huge range of debilitating and life-threatening illnesses – including cancer, heart and brain diseases, spinal-cord injury and diabetes.

Stem-cell therapy promises stunning cuts in hospital and medical-care budgets. Expensive drug courses, postoperative and long-term care of the aged could become a thing of the past. Each individual would have a set of stem cells in storage matching their DNA. Treatment for a wide range of illnesses would involve injections of appropriately enhanced cells to replace damaged tissue or defective blood, or absent bone, cartilage and muscle, or degenerating brain and nerve cells.

Several trips to the doctor each year would replace in most cases the vast expense of hospitalisation and surgery. The elderly would be given a new lease of life, prolonging their productive years and reducing the rising costs of geriatric care. Treatment of kidney damage due to diabetes would be an early beneficiary of stem-cell therapy, precluding expensive dialysis treatment. Parkinson's patients would rise from their wheelchairs. Hip-replacement operations would be a thing of the past.

Stem cells are a siren call, moreover, for people who would spare no expense to alter their self-image – a new nose, a full head of hair, greater sexual potency, even a return of youth. If stem-cell research delivers on its promises, it could transform the way we see nature. No longer will we have to accept what is given to us at birth, our looks and health, or even our destined life span.

But first, scientists must settle on the best way to acquire appropriate stem cells – and they must learn sure ways of differentiating them into the required tissue and cell types for therapy. Stem cells exist at different levels of purity and potency, ranging from pluripotent to multipotent. Pluripotent cells can in theory be turned into every and any kind of cell and tissue type, while multipotent cells are capable of being turned into certain restricted kinds of cells.

And this is where our Hampstead-based husband-and-wife team come in. Ilham Abuljadayel, a postdoctoral biotech scientist originally from Saudi Arabia, claims that she has discovered an infallible and cheap technique for changing white blood cells into perfect, pluripotent stem cells – the gold standard of stem-cell values. Her husband, Ghazi Dhoot, a physicist turned merchant banker, originally from north India, has patented the discovery and seeks to develop it to the point where TriStem (named in honour of their three children) can go public.

Abuljadayel claims that she can take half a pint of your blood and within three hours produce a large quantity of pure stem cells peculiar to your personal DNA. "What we're doing," she tells me, "is taking cells and turning their clocks back to make them young primitive cells, capable of becoming any cell or tissue type in your body." She calls the process "retrodifferentiation". At the same time, and this is the crucial point, she claims that she has already found ways of reprogramming these stem cells into a variety of specialised cells and tissues that could mend a damaged heart, treat Parkinson's disease and spinal-cord injury, and cure diabetes. And that's just the beginning.

So why isn't the world hailing her discovery and seeking to adopt it? The answer is in the fraught connection between stem cells, the complex development of the human organism from the embryo, and the pace at which establishment science moves when faced with new discoveries.

Pluripotent stem cells exist in a natural state in the human embryo, which looks like a ball of cells no bigger than a full stop on this page. Pluripotent stem cells of varying efficacy are to be found in foetal tissue, the umbilical cord and in various parts of the adult body, including bone marrow. The accepted wisdom among scientists in this frenetically expanding research field is that embryonic stem cells alone contain the best potential to be turned into any kind of organ tissue, blood type or brain cell.

But if the TriStem technique works, it means that pluripotent stem cells can now be cheaply and simply created from your own blood, bypassing a host of scientific and ethical problems that surround the exploitation of embryonic stem cells. However, the prospects for Abuljadayel's technique are problematic, not least because many scientists in the field are counselling caution. They insist that embryonic stem cells are naturally primitive and therefore the safest for exploitation.

They argue that stem cells produced by reprogramming of adult cells found, for example, in blood, could be compromised in ways as yet unknown. And yet a huge constituency of people, including the Pope and George W Bush, along with ethicists, religionists, politicians and huge numbers of the general public, believe that exploiting embryos to harvest stem cells is ethically unacceptable, since they see the embryo as the beginning of individual human life.