On January 7, a team from the University of Maryland School of Medicine reported the world‘s first transgenic pig heart transplant in a male patient with advanced heart disease. It has been a week since the operation began, and the industry is highly concerned about the patient’s condition. The first financial reporter learned from Professor Wu Zhongjun, director of the Artificial Organ Laboratory at the University of Maryland on January 15, that the patient had been released from ECMO (extracorporeal membrane oxygenation) two days ago and started walking a day ago.
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Human trials of xenografts are necessary
According to University of Maryland surgeon Muhammad Mohiuddin, who led the transplant research team, the team will monitor patients’ immune responses and heart function and continue with controlled clinical trials. If suitable patients emerge, they hope to be able to apply for more urgent procedures for xenotransplantation.
The patient responded well one week after receiving the transplant, without acute rejection, which means xenotransplantation of genetically modified organs is one step closer to success and will provide a wealth of data on the possibility of xenotransplantation, although this cutting-edge technology is still There are many ethical and technical barriers.
To date, most xenotransplantation studies have been performed in non-human primates. The researchers hope that the first pig-human xenotransplantation of the heart will facilitate the initiation of human clinical trials of xenotransplantation and help advance it to address ethical and regulatory issues.
Academician Ge Junbo of the Department of Cardiology, Zhongshan Hospital Affiliated to Fudan University commented: “This event is an important milestone in the history of human organ replacement therapy. It is not only end-stage cardiovascular disease, but also has epoch-making significance for other organ replacement therapy.”
Last year, surgeons at NYU Langone Health transplanted kidneys from the same genetically modified pig into two patients with brain-dead kidney disease, and the organs were not rejected.
In this regard, Ge Junbo believes that the successful implementation of the first heart xenotransplantation operation is more significant because the tissue complexity of the heart is far more than that of the kidney.
“From a few human patients, we learned something we couldn’t learn from dozens of monkeys,” said David Cooper, a transplant surgeon at Massachusetts General Hospital in Boston. Hospitals and see how these hearts and kidneys are doing in patients.”
The researchers say it is important to study xenotransplantation in humans rather than animals because animal models are limited. Jeremy Chapman, a retired transplant surgeon at the University of Sydney, Australia, said: “The differences between species prevent us from using the model further to predict clinical outcomes, as non-human primates tend to have features that humans do not have. antibodies that attack proteins on pig organs.”
In addition, researchers need to be able to study the physiology of the pig heart, such as whether it beats at the same rate as a human heart.
Gene editing tests are expensive
In recent years, significant progress has been made in xenotransplantation with the advent of the gene editing technology CRISPR–Cas9. The latest transplant at the University of Maryland Medical Center (UMMC) used ten genetically modified pig organs. Although the combination appeared to work, it was unclear how many genetic modifications were necessary.
Professor Megan Sykes, a surgeon and immunologist at Columbia University in New York, said: “Evaluating every genetic modification requires more validation of scientific data. We need this information because some gene editing also has may be harmful to humans.”
In addition, xenotransplantation is currently still limited by the availability of genetically modified pigs as well as by regulatory hurdles. The FDA needs to ensure that these genetically modified pigs meet very strict medical-grade facility standards. There is only one company in the United States that can supply this genetically modified pig, Revivicor, based in Blacksburg, Virginia, which can supply genetically modified pigs to standard medical-grade facilities and clinical use.
David Ayares, CEO of Revivicor, revealed that the company’s pigs are currently raised in a facility near Birmingham, Alabama, and the company is preparing to build a larger facility in Virginia that it hopes will eventually supply hundreds of dollars a year. an organ.
For two decades, Ayares has been working on the design of this genetically modified pig, testing various genetic modifications to assess how they limit the rejection response to xenotransplantation in humans and other primates.
But such genetic testing is very expensive. It has been revealed that transplanting a pig heart into a baboon costs about $500,000 per transplant. Cooper of Massachusetts General Hospital believes that the model for a possible future xenotransplantation could be genetic modification of specific organs and recipients.
Several other companies are also designing transgenic pigs for solid organ transplants with different genetic modifications, such as eGenesis in Cambridge, Massachusetts, and NZeno in Auckland, New Zealand. Although these businesses do not yet have medical-grade facilities, the cost of trials for genetic testing is expected to drop in the future as more companies get involved.
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