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First Successful Pig-Kidney Transplant Transforms Medicine

The first-ever reported use of a gene-edited pig kidney was transplanted into a living individual last week in Massachusetts. The individual, Mr Richard Slayman, is a 62-year-old man from Weymouth, Massachusetts and was suffering from end-stage kidney failure following a kidney transplant in 2018.  

The surgery took four hours and was a gleaming success, not only for the surgical team and Mr Slayman himself but for medicine as a whole. According to the surgical team led by Riella, Kawai, and Nahel, once the transplant was complete, the kidney pinked up and the ureter began producing urine, an excellent sign that the kidney was functioning. Indeed, it was, and the hope is that the kidney will remain functioning for many years to come.  

Image: Wikimedia Commons

Pictured: Mass General Hospital, where the surgery took place.

Kidneys are vital organs that are responsible for filtering waste products like urine from the bloodstream. By doing so, they prevent a toxic build-up of waste, control blood pressure and maintain our bodies' homeostasis, or our internal environment, by keeping water, salt and mineral levels balanced. Each day our kidney filters through 142 litres of blood, and it does so quite effectively, but sometimes these organs fail: the results can be disastrous. Without treatment, kidney failure may cause anaemia, bone and heart disease, high blood pressure, and even strokes.  

One method used to treat kidney failure is haemodialysis, where blood is filtered through an artificial kidney machine to filter and clean blood. However, this process can require frequent hospital visits and is a lengthy procedure with numerous side effects, including sleep problems, muscle cramps, and low blood pressure. As a result, people have turned to kidney transplants. 

The first kidney transplant was performed in 1954 by Dr Joseph Murray, also in Massachusetts. Since then, there have been numerous success stories, but due to the possibility of organ rejection and nationwide organ shortages, other methods are being explored. Xenotransplantation is the transplantation of an animal's organ into a human and has been of particular interest in recent years due to the advent of gene editing technologies like the CRISPR-Cas9 system. By editing the embryos of miniature pigs, many companies including eGenesis (which synthesised the kidney in question) are able to create organs from animals which are suitable for the human body. Using this technology, countless lives may be saved by creating patient-specific organs, reducing the possibility of organ rejections and increasing the likelihood the organ will remain functional for longer. 

The kidney of interest had 69 genome edits, three genes of which were removed to stop the synthesis of sugars marking the kidney as a pig's organ, and seven of which mimicked signals on a human's kidney, all to prevent organ rejection following the transplantation. The remaining 59 edits were antiviral measures to prevent disease-causing viruses, which lurk in the pig genome, from attacking human cells or causing an immune response.

But why use an animal's kidney? There have been countless papers recently on growing organs in petri dishes, so where are they? In fact, we haven’t actually grown a full organ yet, only coming so far as organoids, small versions of organs, that would not fill the role of a fully formed organ. Although we have been able to replicate the simple structures of brains, livers, lungs, and many other organs, we are a long way from transplanting these organs into real, living people. As a result, xenotransplantation is a necessary step to help the thousands of people across the world in need. 

With 90,000 people in the US alone awaiting kidney transplants, and 3,000 every year dying whilst waiting, the hope is that through compassionate use of animal organs — when the person's life is in danger and there are no other treatment options — we will be able to save thousands of lives across the globe. Today, Mr Slayman is said to be recovering well from his surgery and we all wish him and his new kidney all the best.

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