Medics are on the brink of a major breakthrough, meaning conditions  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 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.
 
One 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.
 
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.
 
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.