Researchers have converted lungs donated for transplants to a universal blood type in a step towards creating neutral organs that could expand the options for patients awaiting a transplant.

The achievement could mean blood-matching no longer being an issue, resulting in more lives being saved and fewer organs being wasted.

Scientists were able to treat donated lungs and convert them from blood type A lungs into universal type O without causing any damage to the organs, and essentially making them neutral.

Lung transplants can be the last resort for people with end-stage lung diseases such as cystic fibrosis, but wait times can be extremely long due to constant shortages of donor organs.

These waits are made worse by the need to match the blood types of the donor and the recipient, for the best chance of a successful transplant.

The need to match blood types also leads to the waste of unmatched organs and disproportionately impacts certain patients.

For example, patients with blood type O have a 20% greater risk of dying while waiting for a suitable donor.

Marcelo Cypel, surgical director of the Ajmera Transplant Centre and the senior author of the study, said: “With the current matching system, wait times can be considerably longer for patients who need a transplant depending on their blood type.”

He added: “Having universal organs means we could eliminate the blood-matching barrier and prioritise patients by medical urgency, saving more lives and wasting less organs.”

If someone who has type O blood received an organ from a type A donor, for example, it is likely the organ would be rejected.

Therefore donor organs are matched to potential recipients on the waiting list based on blood type, among other criteria.

On average, patients who are type O wait twice as long to receive a lung transplant compared to patients who are type A, explained Aizhou Wang, scientific associate at Dr Cypel’s lab and first author of the study.

Dr Wang said: “This translates into mortality. Patients who are type O and need a lung transplant have a 20% higher risk of dying while waiting for a matched organ to become available.”

But this issue is not unique to lungs, and the disparity exists for other organs, where a patient who is type O or B in need of a kidney transplant will be on the waiting list for an average of four to five years, compared to two to three years for types A or AB.

Dr Wang said: “If you convert all organs to universal type O, you can eliminate that barrier completely.”

In the new study, human donor lungs not suitable for transplantation from type A donors were put in a machine that pumps nourishing fluids through organs, enabling them to be warmed to body temperature, so that they can be repaired and improved before transplantation.

One lung was treated with a group of enzymes to clear the antigens – which determine blood type – from the surface of the organ, while the other lung, from the same donor, remained untreated.

Each of the lungs was tested by adding type O blood and it was found that the treated lungs were well tolerated, while the untreated ones showed signs of rejection.

The team treated eight blood type A lungs and discovered the treatment removed more than 97% of blood type A antigens within four hours.

Researchers plan to conduct further studies in mice to determine the long-term benefits and viability of lung transplants converted with their method.

The study, carried out the Latner Thoracic Surgery Research Laboratories and University Health Network’s Ajmera Transplant Centre, is published in Science Translational Medicine.