Two and a half months after a team at NYU dubiously claimed they performed the very first pig-to-human organ transplant, a team at the University of Maryland Medical Center appears to have actually done it.
The center announced Monday evening that surgeons had successfully transplanted a genetically modified pig heart there into a 57-year-old patient with end-stage heart disease. The patient, David Bennett, was too ill to qualify for a human donor and had no other options.
“I consider this to be a tremendous breakthrough for the field,” said Jim Markmann, head of transplant surgery at the MGH and an expert in xenotransplantation not involved in the UMD case, in a report. E-mail.
In the decades-long effort to make xenotransplantation a reality, the new report differed from that of October on key points. Most blatantly, the NYU patient was already brain dead. Doctors sutured a pig kidney outside of her body and could only determine if the patient immediately rejected the foreign organ. As predicted by years of monkey experiments, she didn’t.
The new procedure may offer the first test to find out whether porcine organs, when raised with the right battery of genetic modifications, can actually replace or complement human organ donation and allow patients to live functional lives.
So far, everything is fine, according to the UMD, although doctors have warned it is still early days. Bennett is doing well three days after the procedure, the center said. the New York Times reported that he was still on a cardiopulmonary bypass machine, but this is common for any new heart transplant recipient.
“It was either to die or to do this transplant. I want to live. I know it’s a hit in the dark, but it’s my last choice, ”Bennett said in a statement provided by UMD. “I can’t wait to get out of bed after I have recovered.”
The news comes as xenotransplantation, after years on the medical fringes, seemed to be getting closer to reality, potentially offering an alternative to the hundreds of thousands of patients in the United States and around the world awaiting organs. After a high-profile attempt to transplant a baboon heart to a baby with a congenital heart defect in 1983 failed, researchers and several companies tried to use recombinant DNA techniques to make pigs with organs that humans can accept.
These efforts disintegrated virtually overnight after the discovery of a retrovirus common to pigs, terrifying health officials then faced with the height of the HIV crisis in the United States. But over the past decade, as new research has reduced concerns that the porcine endogenous retrovirus, or PERV, as it is called retrovirus, could be transmitted to humans and that new tools for genome engineering have become available, the field has revived.
Bennett’s new heart came from Revivicor, a subsidiary of United Therapeutics, a $ 9 billion biotechnology company for rare diseases. The same company provided the NYU kidney, but Bennett’s heart came from pigs with many more genetic modifications: 10 in total – four pig genes inactivated to prevent rejection, six human genes inhibited to promote tolerance and an additional inactivated porcine gene. to prevent excessive tissue growth.
Scientists are divided on the exact number of changes needed to avoid rejection. Revivicor competes with a few university labs and venture capitalist favorite eGenesis to make xenotransplantation a reality. eGenesis, founded by genetic engineer Luhan Yang and backed by more than $ 260 million from private investors, is making an even higher number of modifications – they never said how many – as they attempt to eliminate completely the PERV.
To be clear, however, Bennett’s surgery is still a remarkably early stage in the standard drug development process. The FDA has approved the procedure under compassionate use, an emergency measure to make investigational therapies available to patients with no other options.
For xenotransplantation to truly become a medically approved product, a company or an academic team will need to demonstrate that the modified porcine organs are safe and effective in a clinical trial.
Revivicor, eGenesis, and others are trying to complete the monkey studies needed to get clearance for such a trial. They will likely need to show that non-human primates have consistent survival after transplantation. Experts suggest we could start in 2023.