We'll soon be building new hearts to order in just 24 hours say stem cell scientists

Dean Third used to look forward to weekends spent refereeing local football matches, and outings with his young family. But now even walking to the end of the road can leave him breathless and exhausted.

For the past four years, the father of four has suffered from dilated cardiomyopathy (DCM), a disease of the heart muscle which causes it to enlarge, affecting its ability to pump blood to the arteries.

The condition afflicts 12,000 people in the UK, and for most sufferers the cause is unknown. If uncontrolled it can be fatal, and patients must adhere strictly to a regime of medication.

Breakthrough: Dean Third studies a rat's heart built using stem cells, seen in close-up below

For Dean, a mature student from Brightlingsea, Essex, the only chance of a normal life is a heart transplant. But he says: 'I am way down the list because there are so few. I may die before one becomes available.'

Dean, 39, also has to live with the knowledge that he may have given the disease to his children. Although his wife, Cathy, 40, does not have it, there is a 50 per cent chance he could have given it to Nadine, 16, William, 14, Ross, 12, and Charlotte Rose, nine.

They will have to be monitored for the rest of their lives.

However, Dean has just taken part in a BBC Horizon TV programme where he discovered that medics are on the brink of a major breakthrough, meaning conditions such as his could be cured by making new hearts from the patient's own stem cells.

Often referred to as the body's 'building blocks', stem cells have the remarkable potential to develop into many different cell types in the body during early life and growth. In addition, in many tissues they serve as a sort of internal repair system, dividing without limit to replenish other cells as they die out.

When a stem cell divides, each new cell has the ability either to remain a stem cell or become another type of cell with a more specialised function, such as a brain cell, a red blood cell or, as Dean learnt, healthy heart cells.

The documentary team examined the cases of three patients with chronic conditions to discover whether, within their lifetimes, they might be cured.

Dean visited Dr Anthony Mathur, from University College London, to witness the world's first trial using stem cells taken from bone marrow. The cells are injected into the muscles of the heart to regenerate damaged tissue.

He also travelled to Minnesota in America to visit laboratories carrying out research to produce new hearts using stem cells.

Although the research has so far been used only to produce a new rat's heart, experts believe the prospects for the future are limitless.

Dean's health problems began in May 2005 when he began to feel lethargic and nauseous and assumed he was coming down with a cold.

'I was absolutely exhausted and just wanted to sleep, which was just not like me. My GP thought it was a stomach bug. I'd passed a medical the month before because I was planning to join Essex Police as a special constable, so I thought the doctor was right and I'd get over it.'

But two weeks later Dean's wife went to check on him and found him almost unrecognisable. 'I was horribly bloated and struggling to breathe,' he says. 'It was really frightening. My heart was pounding as if I'd just run a sprint. Cathy called the doctor and I was rushed to Colchester Hospital.'

An echocardiogram - an ultrasound scan of the heart - revealed cardiomyopathy. Dean's rapid heart beat - 220 beats per minute instead of the normal 80bpm - was a complication of his condition.

Doctors were able to stabilise him, but he was in hospital for three weeks before going home. 'When I got home and could barely walk down the stairs, I knew that my life was never going to be the same. I am now registered as disabled.'

DCM can be triggered by a virus, poor nutrition, pregnancy and childbirth. But Dean believes his illness is hereditary. 'I found out my cousin died of it aged 27, and that my two uncles also suffer from it,' he says.

The progress of the disease varies between patients. In some cases the condition remains stable, while in others the heart gradually deteriorates. Sudden death, due to severe arrhythmia (irregular heart beat) bringing on a stroke, is a rare but not unheard-of consequence.

Dean now takes the blood-thinning drug Warfarin and beta blockers, which slow the heart rate.

But the prospect of creating new functioning hearts from a patient's own tissue is now a real possibility. While researchers have yet to get results in human subjects, scientists at the University of Minnesota have produced new working hearts using rats' and pigs' stem cells.

Dr Doris Taylor, of the Centre for Cardiovascular Repair, has taken a heart from a dead rat and drained it of all its stem cells so that it is nothing more than a lump of protein, a process called whole-organ decellularisation.

She then took stem cells from a live rat and injected them into the inert heart. The stem cells are able to recognise it is a heart and begin working to form new cells, producing a new organ.

She says: 'The main problem of heart transplants is the body rejecting the organ. If all the tissues come from the original patient, there is minimal risk of rejection.'

Dr Taylor thinks that their research could provide new organs within 24 hours for desperate recipients.

Dean admits: 'For the first time, I've been given hope.'

• Horizon, BBC2, Tuesday, 9pm.