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A patient's own blood has been used to make personalised stem cells, which doctors hope will eventually be used to treat a range of diseases.

The team at the University of Cambridge says this could be one of the easiest and safest sources of stem cells.

In a study, published in the journal Stem Cells: Translational Medicine, the cells were used to build blood vessels.

However, experts cautioned that the safety of using such stem cells was still unclear.

Stem cells are one of the great hopes of medical research. They can transform into any other type of cell the body is built from - so they should be able to repair everything from the brain to the heart, and eyes to bone.

One source of stem cells is embryos, but this is ethically controversial and they would be rejected by the immune system in the same way as an organ transplant.

Researchers have shown that skin cells taken from an adult can be tricked into becoming stem cells, which the body should recognise as part of itself and would not reject.

The team at Cambridge looked in blood samples for a type of repair cell that whizzes through the bloodstream repairing any damage to the walls of blood vessels. These were then converted into stem cells.

Dr Amer Rana said this method was better than taking samples from skin.

"We are excited to have developed a practical and efficient method to create stem cells from a cell type found in blood," he said.

"Tissue biopsies are undesirable - particularly for children and the elderly - whereas taking blood samples is routine for all patients."

Dr Rana told the ����ý the cells also appeared to be safer to use than those made from skin.

"The fact that these appeared to be fairly stable is very promising," he said.

"The next stage obviously is to say, 'OK if we can do all this, let's actually make some clinical grade cells,' we can then move this technology into the clinic for the first time."

Prof Chris Mason, an expert on regenerative medicine at University College London, said there was some "beautiful work" coming out of the lab in Cambridge.

"It's a hell of a lot easier to get a blood sample than a high quality skin sample, so that's a big benefit," he said.

"However, induced pluripotent stem cells [those converted from adult cells] are still very new, we need far more experience to totally reprogram a cell in a way we know to be safe."

The British Heart Foundation said these cells had "great potential".

The Medical Research Council said there was "rapid progress" being made in the this field.