The human body is one of the most amazing, complex, and durable machines that we know of. It’s a masterpiece of complex biochemistry and anatomical design, but even so it is prone to all sorts of failures. The body consists of a number of structures called organs that each perform a crucial and specialized job. Some, like the heart, will cause death quickly if they fail. Others, such as the kidneys, can take years before their gradual failure finally takes its toll on the rest of the body.
For most of human history, when an organ was damaged or failing, there was very little that anyone could do. The only organs you had were the ones that you were born with. Then, in the middle of the 20th century everything changed.
Have a Kidney, Have a Heart
In 1954, Drs. Murray and Hume performed the first ever transplant from a living donor to another person. This changed the game completely. People with organ failure were no longer terminally ill. They could live almost normal lifespans if they could find a donor. In 1962, the first successful transplant from a deceased donor was carried out, widening the available supply of kidneys.
The second half of the 20th century was a veritable revolution in organ transplant science. Other organs would soon follow – the pancreas, the liver, the lungs, and then the big one in 1967, the heart. South African Dr. Christiaan Barnard made history when he performed the first-ever successful heart transplant in Cape Town at the Groote Schuur hospital.
We also saw the discovery and introduction of powerful anti-rejection drugs, which almost immediately improved the five-year prognosis for transplant recipients.
In 1992, something even more incredible happened: a xenotransplant. In other words, an organ was transplanted with the patient surviving some time afterwards. This was the 34th attempt to transplant organs from other species, but advances in immunosuppressant drugs and surgical techniques improved the prospects. However, we still haven’t quite cracked the secret of making organs from other species work for us. It’s a pity, because one of the biggest problems today is that people are living so much longer that the supply of organs is critically low.
The Pain of Rejection
Those immunosuppressant drugs are needed because, even if you receive an organ from a close relative, your body is still likely to identify it as being foreign and may reject it. The problem is that suppressing the immune system makes it more likely that you will die from other causes, such as infection or cancer. Skin cancers and lymphomas are much more common in people who take immunosuppressors.
As it stands, only about 50% of people who receive heart transplants live over 10 years past that point. Of course, many recipients are quite advanced in age, but many in that 50% die quite quickly from a side effect of the transplant itself. If only we could make an organ that could be transplanted and not require risky drugs such as immune suppressing chemicals. That’s a Holy Grail of modern medicine, and we are well on our way to getting there.
Stem Cell Miracles
We all begin life as a single cell – the embryo. This cell contains all the information needed to make a human being. It divides into daughter cells and these divide again. This exponential cell division creates enough biomass to become a fetus, ready for birth.
The cells differentiate themselves into all the various organs and tissues of the body. Through extremely complex chemical signaling, each cell figures out if it should be part of a vein or muscle or the brain. These differentiated cells will then divide into daughter cells that are copies of their new specialized form, creating all the parts for what we know as human anatomy.
We call these early, undifferentiated cells “stem cells”, because all other cells stem from them. Stem cells are present in adult humans in small quantities and we are now learning that they can be harvested in order to coax them into becoming any tissue you want. At least in theory. Using this knowledge, we could one day grow for a person a copy of their own organ, except that this one will be young, healthy, and new. Once implanted, the body will be none the wiser. The substitute will be recognized as the right organ and no suppression of the immune system will be needed. Instead of adding a few years onto a person’s life, these sorts of transplants could extend life beyond what we thought is the limit of human lifespan. Then there’s simply saving millions of lives, eliminating the past desperate waiting for an organ that may never have come.
Getting stem cells has been an issue for a while. Embryos were the main source for quite some time. The idea was that some of your stem cells that were left over at birth would be stored and then if you needed a new organ one day they could be put to use. The problem is that this would only benefit people who are still to be born. Science then figured out that there are still small supplies of stem cells in adult humans, but they aren’t exactly comfortable to extract.
In 2014, a major breakthrough came. It turns out that you can take existing cells and make them revert back to their stem cell form.
So one day we may see stem cells used to repair organs instead of completely replacing them, or the creation of new cloned organs using stem cells and technologies such as bioprinting.
Breathing New Life into Organs
One interesting development is the notion that organs from deceased donors that would have been rejected before can be repaired to the point where they become viable for transplant. Various systems now exist to keep organs such as lungs, livers, and hearts alive and active for weeks outside the body while they heal and become healthy again. It also brings up the possibility of removing the diseased organ from a patient who needs a transplant temporarily and fixing it up outside the body, reversing the degeneration.
We are on the cusp of many more regenerative medicine breakthroughs, and hopefully in the near future the idea of a organ donation waiting list will be a thing of the past.