Scientists don’t like the word ‘breakthrough’. It tends to produce the response: ‘Hype!’. But the first transplant of a whole, complex organ, engineered specifically for a particular patient, might really deserve the ‘b’ word.

Stem cells and immature cells are already being used to treat blood cancers, to repair skin and the cornea of the eye. Trials are underway for the use of stem cells to help repair damaged hearts and to prevent type 1 diabetes. Insulin-producing tissue can be transplanted and bits of bladders have been made and successfully implanted. But creating a whole organ is a big step forward. A step that would have been impossible without prior experiments on animals – pigs in the case of this trachea transplant.

The trachea was a particularly good candidate for tissue engineering because of its non-living "matrix" - a collagen structure that can form the perfect scaffold for cells to be grown on it. Stem cells derived from the patient, put into a donor’s trachea, stripped of its own cells, became flexible cartilage for the outside of the new windpipe and her own epithelial cells were used to line the inside.

What does this mean for the future? Well, we are not going to be able to produce custom-made replacements for the most complex organs in the body – hearts, brains, kidneys – any time soon. But other potential targets for this kind of tissue-engineering technique include bladders, eye balls and the larynx. Beyond this, there aren't many parts of the body that have this same kind of natural structural matrix that could be derived from a donated organ.

Researchers are trying to create artificial matrices for sculpting cartilage and bone and the extent to which they are successful may determine whether or not we can expand these techniques to other organs, or make this kind of transplant more cost-effective.

At the much earliest steps on the ladder to treatment, researchers are now trying to grow entire organs – hearts, kidneys, pancreases – from embryonic stem cells, in test tube conditions.

The capacity of embryonic stem cells to turn into virtually any other kind of cell obviously gives them the most potential for organ and tissue replacement. But there is much to learn about how to grow and control them and prevent them being rejected, before they are likely to be widely used. And there are exciting new developments that make it possible to create cells that behave just like embryonic stem cells by genetic modification of adult skin cells. It’s not inconceivable that, down the road, there will be ways to take a few cells from the skin of a patient, convert them into safe stem cells and to use those cells to treat conditions from stroke or heart failure to spinal cord injury or diabetes.

I’m trying to avoid the ‘b’ word and trying not to give false hope. The fairytale developments are likely to take decades rather than years. But advances such as this trachea transplant are the kind of encouragement that we need to have hope that stem cells and tissue engineering will eventually deliver the promised revolution in medical treatment.

Colin Blakemore is Professor of Neuroscience at Oxford and Warwick, and is a former chief executive of the UK Medical Research Council

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