Context : U.S. surgeons have successfully implanted a heart from a genetically modified pig in a 57-year-old man, a medical first that could one day help solve the chronic shortage of organ donations.
- Xenotransplantation is any procedure that involves transplanting cells, tissues or organs from one species to another.
- Xenotransplants were largely abandoned after the 1984 case involving Stephanie Fae Beauclair, better known as Baby Fae, in California. Born with a fatal heart condition, the infant had received a baboon heart transplant but died within a month of the procedure due to the immune system’s rejection of the foreign heart
- Xenotransplantation could potentially provide an unlimited supply of cells, tissues, and organs for humans. Any disease that is treated by human-to-human transplantation could potentially be treated by xenotransplantation.
- Organ xenotransplants could include whole hearts, lungs, livers, kidneys or pancreases. Tissue xenotransplants could include skin grafts for burn patients, corneal transplants for the visually impaired, or bone transplants for limb reconstruction.
- Cellular xenotransplants may provide treatment for people with diabetes, Alzheimer’s or Parkinson’s diseases.
- The most serious risk of xenotransplantation appears to be cross-species transmission of undetected or unidentified animal infectious agents to patients that could, in turn, be transmitted to the general public. The worst-case scenario would be a major new epidemic.
- The potential risk of cross-species infection is largely compounded by the practices of patient immunosuppression for transplantation.
- Some of the other scientific concerns surrounding xenotransplantation include immune rejection, uncertain efficacy/viability (whether it will work), and whether high levels of immunosuppression will leave the patient vulnerable to more frequent infectious diseases or cancer.
India’s 1997 transplant
- In 1997, two surgeons — Dr Dhani Ram Baruah, a transplant surgeon from Assam, and Dr Jonathan Ho Kei-Shing, a Hong Kong surgeon — made a bold announcement.
- The duo conducted a pig-to-human heart and lung transplant in Guwahati on a 32-year-old farmer, Purno Saikia.
- To address the rejection problem, Baruah had “developed a new anti-hyperacute rejection biochemical solution to treat the donor’s heart and lung, and blind its immune system”.
- Unfortunately, Saikia could not make it. He died a week later from an infection.
- Baruah and Kei-Shing were arrested for culpable homicide and imprisoned for 40 days.
Animal’s contribution to medical sciences
- Pig valve for heart A properly functioning valve ensures that blood flows in the right direction through the heart. Sometimes they fail to do their job, leading to heart valve disease. Surgeons replace the damaged valve with a mechanical one or tissue valve (created from animal tissue) made from pigs, cows or human heart tissues. In September 1965, scientists successfully replaced the aortic valve in a human with a porcine one for the first time. Tissue valves can last for about 15 years and are preferred over mechanical ones.
- Blood thinners, skin grafts : Heparin is an anticoagulant that keeps blood clots from forming during surgery. It also finds use in certain medical conditions. This compound is sourced from pigs. Scientists found them to be cleaner than those derived from cows or dogs. In 2019, experts from the US announced that live cell, genetically engineered pig skin could temporarily close a burn wound.
- Diabetes treatment : Until the 1980s, humans with type I diabetes or insulin-dependent diabetes relied on animal insulin to control their blood glucose levels. Insulin is a hormone produced by the pancreas. People with type 1 diabetes make little to no insulin. This is because their immune system attacks this hormone. In 1921, Frederick Banting and his assistant Charles Best extracted insulin from dogs for the first time. In the years that followed, experts began extracting this hormone from the pancreas of pigs and cows. Currently, human-derived insulin is also available in the market. Researchers are also studying how to transplant insulin-producing islet cells from pigs to humans. This could eliminate the need for insulin shots.
- Growing organs : Human-pig embryos could allow scientists to grow human organs in the lab and transplant them to people in need. In 2017, a study published in Cell journal developed a human-pig hybrid by growing human cells inside early-stage pig embryos in the lab.
- In 2017, Chinese surgeons reportedly transplanted pig cornea to restore sight in a human.
- In 2020, US experts attached a genetically-altered kidney to a brain-dead person. They monitored the new organ for the next 54 hours. The transplanted kidney functioned well. But long-term consequences are still unknown
- The next breakthrough was the latest pig-heart transplant that was granted authorisation by the US Food and Drug Administration after reviewing experimental data.
About the News
- Surgeons in the US have transplanted a pig’s heart inside a human patient in a bold endeavour that represents a remarkable first in the world of medical science, one whose success could potentially end the years-long backlog of people waiting to receive a healthy organ and open up a brave new world of possibilities.
- Reports say the surgeons went ahead with the transplant that constituted a last-ditch attempt at keeping him alive on January 7 after receiving the go-ahead under compassionate grounds from US health authorities. Such authorisation is required where an experimental medical product is the only option available for a patient faced with a serious or life-threatening medical condition.
- A human transplant had been ruled out with reports saying that such a decision is usually based on poor underlying health condition of the patient.
- This organ transplant demonstrated for the first time that a genetically-modified animal heart can function like a human heart without immediate rejection by the body
- The transplanted heart was harvested from a pig that had undergone genetic editing that saw scientists remove three genes “that would have led to rejection of pig organs by humans” along with one that would have led to excessive growth of pig heart tissue.
- Further, six human genes that would have facilitated the organ’s acceptance by the human body were inserted into the pig genome, meaning that a total of 10 unique gene edits were carried out in the pig by the US biotech firm Revivicor.
- Reports said that on the day of the surgery, the team at UMM removed the pig’s heart and placed it in a perfusion device designed to keep it in readiness for the surgery. Apart from the genetic changes effected in the donor pig, Bennett himself received an experimental anti-rejection drug made by another US-based firm, Kiniksa Pharmaceuticals.