A world where DNA can be rewritten to fix deadly diseases has moved a step closer after scientists announced they had genetically-edited the cells of a human for the first time using a groundbreaking technique.

A man in China was injected with modified immune cells which had been engineered to fight his lung cancer. Larger trials are scheduled to take place next year in the US and Beijing, which scientists say could open up a new era of genetic medicine.

The technique used is called Crispr, which works like tiny molecular scissors snipping away genetic code and replacing it with new instructions to build better cells.

It has been hailed the future of genetic editing because it is far cheaper, easier and more accurate than previous methods of replacing DNA code.

British experts said the technique has the power to be ‘transformative’ for many diseases and said they were expecting to see ‘significant progress in the next few years.’

Dr Lu You of Sichuan University in Chengdu has become the first to inject a man with CRISPR altered DNA

Prof Andrew Sharrocks, of the faculty of biology, medicine and health at the University of Manchester said: “It is clear that with future improvements in the Crispr technology that the current study will be the first of many that attempt to harness this technology for treating human medical conditions.

“Treating cancer is one of the uses but also potentially combating auto-immune type diseases including things like arthritis although a lot more work will be needed to bring that to fruition.

“I would expect similar types of approaches to be pioneered in the next few years as the potential for using this technology in the medical sphere is high and potentially transformative.”

In the case of the Chinese man, scientists led by oncologist Dr Lu You at Sichuan University in Chengdu, took immune cells from his blood and disabled a gene which holds the instructions to build a protein called PD-1.

PD-1 works like an antenna, sitting on the surface of immune cells, and looking out for healthy cells, so that the immune system knows not to attack them.

However cancer masquerades as a healthy cell which is why it is often so deadly because the immune system does not see it as a threat.

Cancer cells hide themselves from the immune system by using the body's own safety mechanism against it

To give the immune system a better chance against cancer, the scientists took immune cells from the Chinese man and altered their DNA to remove the antenna, before increasing them in a lab and injecting them back into the patient’s bloodstream.

Experts say it is effectively like cutting the brakes on the immune system.

The initial phase one trial was carried out for safety, and doctors will be monitoring the man’s progress over the next six months. They are also planning to inject ten more people with genetically edited immune cells in the coming months.

Dr Carl June, of the University of Pennsylvania in Philadelphia is also planning a trial in the US next year which will target three genes to treat cancer, while Peking University is planning Crispr trials for bladder, prostate and renal-cell in China next March.

Prof June said the race had begun to get gene edited cells into the clinic.

"I think this is going to trigger ‘Sputnik 2.0’, a biomedical duel on progress between China and the United States, which is important since competition usually improves the end product,” he told the journal Nature.

Although there are no trials ongoing in the UK at the moment, British scientists have already been at the forefront of genetic editing techniques and are likely to start trials in the near future.

Layla Richards who was given designer immune cells to fight her cancer after all other attempts failed credit: 2015

Last year scientists at Great Ormond Street Hospital and University College London used a DNA snipping technique called TALEN to create designer immune cells which could hunt out and eradicate the leukaemia of 17 month old Layla Richards.

It was so experimental and difficult that it had only ever been tried in mice, and specialists had to apply for emergency permission from health regulators and the hospital’s ethics committee.

However Crispr is easier and is likely to make the practice more widespread for a range of conditions.

Dr Adrian Thrasher of the Molecular Immunology Unit at UCL’s Institute of Child Health said: “At the moment cancer is easiest and safest target as immune cells are modified in lab and given back.

“But there are increasing numbers of applications for genetic disease which will be translated over coming years.”

However some experts warned that there were still several hurdles to overcome. While scientists can manipulate the DNA of cells in the blood it is far harder when disease affect tissues.

Dr Andrew Wood of the Institue of Genetics and Molecular Medicine at the University of Edinburgh, said: “It's certainly true that the technical barriers to the effective application of somatic genome editing are being steadily removed, particularly in tissues such as the blood where patient cells can be removed and edited ex vivo before being reintroduced.

“The major difficulty arises where diseases affect tissues such as the lung or the heart where ex vivo culture is problematic.

“In this case, low editing efficiencies in situ may not be sufficient to yield clinical benefit. Of course, there is a huge global effort to overcome this problem, and it is reasonable to assume that there will be significant progress in the next few years.”