The patient was 57-year-old David Bennett, who suffered from an incurable terminal heart disease. The operation was successful, and the recipient is still feeling well three days later. Experts say that for Bennett, the surgery was the only chance to save his life. The patient will be closely monitored by doctors for the next few weeks.
1.Patient denied heart transplant from human and artificial heart
The University of Maryland Medical Center denied Bennett a human heart transplant. Other leading transplant centers did the same after reviewing the patient's medical history. The use of an artificial heart was also contraindicated. The FDA issued an emergency authorization for the experimental surgery on New Year's Eve because only an immediate transplant could save the man's life.
Bennett was informed that the surgery was experimental and involved unknown risks. The surgery was performed by Bartley P. Griffith, M.D., professor of transplant surgery.
Organs from genetically modified animals can replace organs from human donors
Transplanting organs between organisms of different species is called xenotransplantation and is associated with high risks for the recipient. According to doctors, the surgery proves that organs from genetically modified animals can effectively replace human organs without causing immediate rejection by the immune system. This could solve the problem of a shortage of donor organs, as well as save the lives of patients who are contraindicated for organ transplantation from human donors.Â
3. Pig genome was modified to reduce the risk of rejection
To prevent rejection, experts used not only conventional means, but also an experimental drug manufactured by Kiniksa Pharmaceuticals. In the UHearts™ donor pig, developed by the regenerative medicine company Revivicor, three genes that have been shown to be associated with rejection of an animal organ by the human body were suppressed. A gene contributing to excessive heart tissue growth in the pig was also knocked out.
In addition, six human genes were inserted into the animal's genome to help the patient's immune system "accept" the foreign organ. Genetically modified pig organs have received special attention among xenotransplantologists because of the physiological similarities between pigs and primates, including humans.
4. Scientists have been perfecting xenotransplantation for 30 years
The University of Maryland School of Medicine received a $15.7 million grant to evaluate the risks of organ transplants between genetically modified pigs and baboons. Dr. Muhammad M. Mohiuddin, Dr. Griffith and their research team have spent the past five years perfecting the surgical technique of transplanting pig hearts into nonhuman primates.
Dr. Mohiuddin's research experience in xenotransplantation was more than 30 years, during which time the scientist published numerous peer-reviewed studies proving that genetically modified pig hearts can function for three years. He showed that the success of transplants depended on the right combination of genetic modifications of the experimental donor pig and anti-rejection drugs.
5. The maximum lifespan of a GM pig heart has so far been about 1,000 days
In 2016, the journal Nature Communication published an article by Mohiuddin demonstrating the successful transplantation of a pig's heart to a baboon. Thanks to the experimental approach, the baboon was able to survive 945 days with the transplanted organ. Normally, the average survival time of xenotransplanted pigs is 180-400 days. In this experiment, a second heart was connected to the monkey's circulatory system without removing the monkey's own organ.
Hundreds of thousands of people are in need of organ transplantation
According to experts, the successful operation has provided the necessary information that will help improve xenotransplantation methods in the future to save hopeless patients. According to official data, about 110,000 people in the United States alone are currently waiting for an organ transplant, and more than six thousand patients die each year before the operation. Xenotransplantation has the potential to save thousands of lives, but the risks are very high, including not only the possibility of a dangerous immune response, but also zoonotic infection.
7.Previously, doctors rejected xenotransplantation because of the death of a child
Xenotransplantation as a method of saving people in need of organs has been criticized by many transplant specialists. The method was first tried in the 1980s, but was abandoned after the infamous case of Stephanie Faye Bockler (aka Baby Faye). The child, born with a fatal heart disease, underwent a baboon heart transplant, but Stephanie died a month later because her immune system rejected the foreign heart. Nevertheless, the pig's heart valves continued to be used to replace valves in humans.
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