Human organ transplants aren’t always possible due to a lack of supply.
Research shows that 10 people in the U.S. die every day while on waiting lists to receive vital organs, as the Federal Drug Administration (FDA) reports. This is why medical advancements are aiming to find other ways to deal with this problem, with an example being xenotransplantation.
What is xenotransplantation?
Xenotransplantation is the process of transplanting or infusing live cells, organs, or tissues from an animal source into a human recipient, as Futurism reports.
It’s a groundbreaking advancement that could change organ donation forever. Here’s everything to know about it.
A Brief History Of Xenotransplantation
Although it sounds like a modern idea, xenotransplantation first came about in the early 1900s.
During that time, organ donation from one human being to another wasn’t possible as a result of ethical questions concerning transplantation. Therefore, animal transplants were considered. Unfortunately, these were not successful.
Then, in 1964, a doctor by the name of Keith Reemtsma successfully transplanted a kidney from a chimpanzee into a human. It worked effectively for nine months. This brought much more attention to the idea of xenotransplantation.
The Many Uses Of Xenotransplantation
Xenotransplantation isn’t just about organ transplants from animals to humans. There are many other ways in which it can benefit and prolong human lives. These include:
- Cell transplants. If we can replace damaged human cells with healthy animal cells, we could find a way to heal diseases such as diabetes and Parkinson’s.
- Tissue transplants. Along with cells and organs, tissues can also be transplanted into human bodies. These could include corneal transplants to encourage healthier vision and bone transplants.
What Animals Are Best For Xenotransplantation?
Interestingly, while we might assume that animals such as chimpanzees would be the best fit for xenotransplantation because they are similar to us in so many ways, this actually makes them unsuitable candidates.
Our similarities mean that there could be an increased risk for cross-species infection. In addition to this, monkeys are undomesticated and don’t do well when they’re in controlled environments.
This makes it much more difficult to raise them according to the same health standards as compared to animals like pigs, who could be raised for xenotransplantation.
There are other reasons why monkeys aren’t suitable for xenotransplantation: their organs are too small and they only give birth to one offspring at a time instead of a litter.
Based on the above, pigs are considered to be more effective donors. Their organs are similar in size to human organs and they are easy to rear for medical purposes. Of course, as with any animal, there are ethical questions involved.
Some animal parts from pigs are already being used in the medical field, and a common one is the heart valve that is used in valve replacement surgery.
However, this isn’t considered to be exactly the same thing as xenotransplantation because the pigs’ heart valves are treated with chemicals instead of being living tissue.
What Is The Success Rate Of Xenotransplantation?
As with any medical procedure, it’s important to know what the success rate is.
When it comes to xenotransplantation, the one-year survival rate has increased from 67 percent to 85 percent over the last few decades, as the Centers For Disease Control and Prevention reports.
That sounds phenomenal, but there are various risks involved.
Dangers Associated With Xenotransplantation
Despite the benefits of xenotransplantation, there are some risks associated with it. These include the following:
- Possible infections. There are concerns that recipients could fall prey to infectious agents, and that these infections could be transmitted to other people as well as the rest of the population. One of the biggest fears is cross-species infection by retroviruses, as this could only show up years after the person has become infected with them.
- Organ rejection. The organs taken from animal bodies could be rejected when placed inside the human bodies, but scientists are trying to find ways to work around this. For example, they want to try to change the immune system of the person receiving the transplant so that it can have greater tolerance for the organ or tissue. Another method is to use genetic engineering to alter the animal’s cells, such as by replacing some animal genes with human genes, in order to make it more acceptable to the human body’s immune system.
Future Developments To Combat Organ Rejection
Technology is currently being developed to help prevent organ rejection after the xenotransplantation process.
It involves breeding transgenic pigs, which are essentially pigs that have been genetically altered. They will have human proteins that make it more difficult for the human immune system to single them out as being foreign.
How these transgenic pigs are bred is by injecting DNA that mimics a human gene into a fertilized pig egg.
That egg is then implanted into a sow. Research has found that this strategy has addressed rejection in non-human primates who received organs from genetically altered pigs, as Bio reports. It’s therefore a promising development for human organ recipients.
What Xenotransplantation Has Already Been Done?
So far, there have been a few successful xenotransplantation attempts, but no human organ projects are approved by the Federal and Drug Administration. Let’s look at some developments that have been made.
- There was the famous case of a child known as “Baby Fae,” born in 1984, who had a malformed heart and survived for a short amount of time by having a baboon heart inside her body. Her story is known as the first successful example of xenotransplantation, but it certainly wasn’t the first attempt.
- Looking back in history, the first xenograft heart transplant was done in 1964. It involved the use of a chimpanzee heart that was placed inside a human’s body.
- Then, in 1966, the first chimpanzee-to-human liver transplant was conducted.
- In 1992, a baboon’s liver was transplanted into a human body.
The problems that were encountered with these transplants were that the human bodies rejected the organs. Immunosuppressive medications weren’t sufficient to prevent such reactions from occurring.
- In 2017, a research team from Emory University in Atlanta, Georgia, found that a GM pig’s kidney had been successfully transplanted into a rhesus macaque monkey for over 400 days before it was rejected, which was an increase of over 250 days since previous trials, as Science magazine reports.
There are various clinical trials that have already been done in xenotransplantation. As Stanford reports, some of these include:
- The use of fetal pig neuronal cells to treat Parkinson’s disease.
- The use of genetically-modified pig liver to treat liver failure.
- The use of baboon bone marrow transplant to treat HIV.
- The use of fetal calf adrenal cells to provide pain relief for end-stage cancer.
- The transplant of pancreatic islets cells from pigs to treat insulin-dependent diabetes in humans.
It’s clear to see that many different organs and parts can be used in xenotransplantation. As research published in Animal Frontiers points out, there’s already been progress made with the transplantation of corneas, kidneys, hearts, and neuronal cells.
Can Xenotransplantation Cure Diseases?
It’s an intriguing idea to think that some human illnesses and chronic diseases could be cured by making use of xenotransplantation. For example, people who suffer from severe heart disease or kidney failure could benefit greatly from receiving healthy animal organs.
As Bio reports, preliminary data that’s been taken from experiments involving pig cells that were transplanted into patients with Parkinson’s disease and diabetes have been encouraging.
But what happens after the animal organ has been transplanted into the human body? What is the human patient’s quality of life expected to be?
The answers are still unclear.
What we have seen is that baboons can only survive with pig hearts for six months. That’s encouraging but there’s so much we still don’t know, such as if this amount of time could be extended.
There are also psychological effects that could be experienced after the transplant, and this combined with the uncertainty of the recipient’s medical future, could certainly impact one’s quality of life. We also don’t know if xenotransplantation could result in other illnesses or health conditions.
Ethics Related To Xenotransplantation
Taking organs from animals for human use is filled with much controversy.
Some of the ethical questions concerning xenotransplantation involve the loss of animal life, not just when it comes to using the healthy animal’s organ for transplantation but also when it comes to how the process needs to be experimented on animals.
Thousands of animals have already been experimented on and have died as a result, which is extremely saddening.
It’s not just the loss of animal life that is disturbing for many people, but also the way in which some animals will have to be bred and genetically modified. An example is seen with the use of pig organs.
Pigs have to be genetically modified and raised in special conditions for their organs to be used in xenotransplantation, as this can ensure greater success when it comes to the pig organs being accepted by the human body.
For some people and animal activists, the killing of an animal in order to improve human health is unacceptable on a moral basis. In addition, conducting research and experiments on the animals, such as when researching immunological factors that cause the body to reject animal parts, is also frowned upon.
Some people also hold the opinion that biotech companies are using xenotransplantation in order to make money, as The Balance reports, and that they are not concerned with animal welfare. Part of their argument is that the long-term consequences of xenotransplantation remain unknown.
How Far Away Are We From Xenotransplantation?
Earlier in this article, we looked at how organ rejection after xenotransplantation is a big obstacle that surgeons face and this, along with issues such as ethics, are delaying the development of xenotransplantation.
That said, it’s important to remember that there have been breakthroughs with xenotransplantation.
An example was seen in 2018, when a research team from the University of Munich found that a technique they developed was enabling baboons to survive for longer periods of time after receiving hearts from pigs. After 25 years of research and study, a baboon could only survive for about 57 days after receiving the transplant.
This study now has found that a baboon can live for six months.
How this was achieved was by the scientists avoiding ice-cold storage solution for the organ before the surgical procedure and instead opting for pumping an oxygenated, blood-based solution of hormones and nutrients through the heart, as Discover reports.
They also gave the baboons medication, such as drugs to lower their blood pressure and a drug that prevents the heart from growing too much, which is a common problem when pig hearts are put into baboons.
It’s clear to see that using transgenic pigs as organ donors can help to reduce rejection of the organ. This still has some problems though – the human patient still requires immunosuppressive drugs in order to control the way their immune system reacts to the organ and tries to reject it.
Pros and Cons of Xenotransplantation
Still feel like you’re on the fence about xenotransplantation? While you might not be if you’re desperate for an essential organ transplant to save your life, consider these pros and cons.
- People won’t have to die on organ waiting lists. This is one of the biggest reasons why xenotransplantation can be so beneficial. It’s a depressing thought that so many people die while waiting to receive a transplant from a human organ donor.
- Xenotransplantation could still be beneficial without long-term success. Even though xenotransplantation research so far has shown limited success instead of long life being gained from the process, giving people who are waiting for organs the use of animal organs could extend their lives until they can receive human organs.
- It will prevent the black market. Selling human organs on the black market is risky, but some people consider it as an option when they’re desperate to save their lives. The use of animal organs as an alternative could help to reduce this exploitative trade that is very unsafe because you’re not guaranteed of the quality and health of the organs or how they were acquired.
- It explores more options for human health in future. Although it will take many people quite a bit of time to get used to the idea of xenotransplantation, if it goes ahead and is successful it could open up further biological research. Using animal antibodies and other parts could even help us find cures for diseases such as cancer.
Cons of Xenotransplantation
- Xenotransplantation is fraught with many ethical issues. There are many ethical and moral issues that come into play when we talk about xenotransplantation. For example, some people criticize xenotransplantation because of religious beliefs, such as that mixing species is against God’s will. Others believe that helping human life by ending the lives of animals is immoral.
- There’s the risk of diseases. Animals can contract some diseases that do not affect humans, but xenotransplantation could change that, bringing many health concerns our way. This could affect not just the organ recipients but the population at large.
- There’s the danger of less longevity. When you receive a heart or other organ from a human donor, you know that average human life expectancy is 72 years, meaning that the organs we’re born with have the potential to last for as long as we live. But animals usually live shorter lives. The average life expectancy of pigs, for example, is 15 to 20 years. That could result in animal organs not lasting a long period of time in human bodies.
- It carries a high rate of rejection. As we’ve already discussed in this article, receiving organs from animals can result in human bodies rejecting them. This requires the use of innovative techniques to combat the problem as well as the administering of many potent drugs, which could have side effects that are intolerable, thus posing more problems.
Future Xenotransplantation Trials
While xenotransplantation is still quite far away, clinical trials could begin early in the next decade, as the Journal of Medical Ethics reports, with kidneys from GM pigs being placed in adult humans.
Depending on how successful this is, it could result in pig heart transplants for children suffering from heart failure.
With more research being done in xenotransplantation and developments to deal with its obstacles, xenotransplantation could change human health forever.
What are some successful alternatives to xenotransplantation?
The use of artificial body parts can help people in some cases, and pacemakers are an example of this. Another example is stem cell research which shows promise, but it is shrouded with ethical concerns.
Research reported by Down To Earth has found that the physiology of pigs and humans is 84 percent similar on a genetic level.
Xenotransplantation could potentially save the lives of millions of people who would otherwise die due to a human organ shortage.
But, there’s no doubt about the fact that using animal organs for human wellbeing is fraught with many concerns, such as the ethics involved. Where do you stand on the issue? Are you excited about xenotransplantation or is it something you think should not occur?