Can a body grow its own spare parts?

Nanoscientist Molly Stevens is working on techniques to enable a damaged heart to repair itself or bone tissue to regenerate
Molly Stevens
Nanoscientist Molly Stevens. Photograph: Andy Hall for the Observer Andy Hall/Guardian

The human body has tremendous capacity to repair itself after disease or injury. Skin will grow over wounds, while cells in our blood supply are constantly being manufactured in our bone marrow. But there is a limit to the body's ability to replace lost tissue. Cartilage cells are notoriously poor at regrowing after injury, for example. As a result, accidents and illnesses – including cancers – often leave individuals with disfiguring wounds or life-threatening damage to tissue. The aim of Molly Stevens, a nanoscience researcher at Imperial College, London, and founder of the biotech firm RepRegen, is a simple but ambitious one. Working with a team of chemists, cell biologists, surgeons, material scientists and engineers, she is developing techniques that will help the body repair itself when it suffers damage. This is the science of regenerative medicine.

What is the potential for boosting the body's ability to regrow damaged tissue?

It depends on the type of tissue. Some will regenerate of its own account more easily than others. Bone is not too bad, for example, while cartilage is very poor. Bone has a good blood supply while cartilage has virtually none, and that makes a key difference in supplying nutrients that boost growth. A patient's condition is also important. For instance, it is more of a problem in older individuals or in those who have diseases that are particularly well advanced.

In any case, even in tissue that regenerates well, like bone, there can be problems – if a severe accident has removed a large chunk of a person's jaw or pelvis, or if they have osteoporosis that is very advanced. The bone tissue will simply not regenerate in these cases and that is when doctors want to help it.

So how do you help bone to regrow?

One approach that we have had considerable success with involves taking quite straightforward materials including simple polymers and using them to boost bone growth in a person. We made them into gels that we could inject into bones.

The key to this technique lies with the fact that our bones are covered in a layer of stem cells. We inject our material under that layer and that wakes up those stem cells. They start to multiply and produce lots of new bone. Then you can take that bone and move it somewhere else in a person's body, a place where they have suffered a severe loss of bone – where they suffered an injury suffered after a car accident, for example. In such a case, we would be using a person's body as a biological reactor. And when you think about it, that makes sense. The best place to grow tissue for yourself is in your own body, after all.

How productive is the technique?

So far, we have been able to generate huge amounts of bone in our experiments using these techniques. In addition, the bone that was made this way was well organised. It had blood vessels and a proper architecture. That allows it to be really strong. We have only done this in animals, in rabbits, but we are now preparing to carry out the same procedures in humans. The aim would be to use bone generated within a person to help with spinal fusion, for example, or for someone who has had part of their jaw removed after an operation to remove a cancer.

We also have developed other materials that work in a slightly different way. Instead of stimulating one part of the skeleton to make bone that would replace a missing section somewhere else in the body, we would use this directly at the affected site. Bone would grow at the affected site. There would be no transplant involved. Essentially, it would help a person grow a new jawbone if theirs had been removed after a cancer operation.

Both these techniques involve the regeneration of bone, but we are also working heart muscle and cartilage cells. We are at a much earlier stage with this work. We envisage making gels that you could inject into the miocardium which is damaged after a person has had a heart attack. This could help the heart to repair itself.

What sections of the population are likely to benefit most from advances in regenerative medicine?

One obvious group of individuals who are likely to benefit most from the development of regenerative medicine is the elderly. More and more people are living to their 80s and beyond as we tackle diseases like cancer and heart illness with increasing success. Organ failure will become an increasing problem among these people. Regenerative medicine will help them regrow lost tissue and help them tackle problems like osteoporosis.

However, my real motivation in getting involved in regenerative medicine has been children. I was completing my PhD in biophysics when I attended a lecture in which a photograph was shown of a little boy with terminal liver failure. He was about two years old and that picture made me switch fields – to regenerative medicine.

We have been working with children's charities since then because of the potential of our techniques to fix failing organs in very young people. That is the big driver. A child with a heart valve problem is going to face multiple surgical operations throughout its life. Or if a child is born with half its face missing, its future is likely to be really distressing. These are heart-rending problems. Regenerative medicine could make an enormous difference to them.

This article was amended on 18 May 2010. The original gave the name of the biotech firm founded by Stevens as Reprogen. This has been corrected.