Genetically modified pig heart is transplanted into the second patient in the world

Doctors at the University of Maryland, in the USA, have once again transplanted a genetically modified pig heart into a human. This is the second patient in the world to undergo the innovative xenotransplantation technique (graft between different species).

The operation was carried out on Wednesday, 20. According to the university, the patient is now breathing on his own and his heart is working well, without the assistance of support devices. It is treated with a new antibody therapy along with conventional anti-rejection medications, which are designed to stop the patient’s immune system from attacking the organ.

David Bennett, aged 57, the first patient to receive a pig’s heart, survived for around two months, a fact that was greatly celebrated by the global scientific community. To give you an idea, the first human to undergo a conventional heart transplant (between humans), in 1967, only lived another 18 days – today, after improvement, the technique saves thousands of lives, including that of Brazilian presenter Faustão.

During the nearly two years since the first surgery, scientists have been investigating the causes of Bennett’s death. His death from heart failure was likely caused by a “number of factors”, they believe, including his poor health before the transplant, which left him hospitalized on a machine for six weeks before the procedure.

The new patient, 58-year-old Lawrence Faucette, with end-stage heart disease, was deemed ineligible for a traditional transplant. Therefore, the Food and Drug Administration (FDA), an American body similar to Anvisa, granted emergency approval for the surgery.

“My only real hope is the pig heart. At least now I have hope and a chance,” said Faucette, a Navy veteran and father of two. “My family has been amazing, so I’m going to fight tooth and nail to stay with them longer.”

His wife, Ann Faucette, agrees. Her only expectation, she says, is more time together, even if that just means the opportunity to drink coffee together on the porch. “Just the simple things we don’t think about when everything is going well.”

How it works?

Since the 1960s, professionals have been studying the possibility of transplanting between different species. In the 1980s there was a realization that pigs were the best option. This is because they are easy to handle and similar, physiologically and anatomically, to humans.

Transplanting a common pig, however, creates a hyperacute rejection (response from the human defense system), which requires immediate explantation (removal of the organ). Therefore, until around 2005, scientists dedicated themselves to genetically modifying these animals. Rejection is also a problem – not on the same scale – in human-to-human transplants.

Gene editing involves gene knockouts (blocks) and knock-ins (additions). The scientist takes cells from newborn pigs, blocks the genes responsible for producing the sugars that generate rejection and inserts human genes to moderate the patient’s immune response. The modified cell is introduced into an egg without a nucleus (without genetic material). Even though it is not cloning, it uses a nucleus transfer technique learned from Dolly the sheep.

Why do we need organs from other species?

The search for “additional organs” has a limitation behind homologous transplants: there are not enough organs for those who need them and thousands die on the waiting lists – which is expected to increase with the population aging trend.

Furthermore, xenotransplants open up a series of unprecedented prerogatives. From more predictability to the procedure, which would result in lower costs, to the possibility of the patient having a “pig brother”, which would help control rejection, as Estadão showed in a report published last year.

Other techniques seek to solve the problem of organ shortage. Among them is cryopreservation, an area that studies the possibility of bringing systems and organs to life after freezing. Here, the objective is to preserve organs. Many are wasted because they cannot stay out of the body for long.

For the first time, scientists at the University of Minnesota (USA) managed to perform “frozen” kidney transplants (cryopreservation) in five mice – a still small group. With the innovative and experimental technique, they stored the organs for up to 100 days.