words by Charlie Ellis, Staff Writer
As of Thursday 21st October, within the UK there are 6125 people waiting for an often life-saving transplant. This number is even larger in countries such as America who have approximately 107,000 people requiring a life-altering transplant according to the American Transplant Foundation. These statistics, as morbid as they may be, show the dire need for more organs that are available for transplantation. As we currently cannot magic up a perfect human organ ready for transplant, there are a few potential alternatives that are currently being researched for their viability.
The most promising of which comes from an animal that you would not expect — pigs. This is possible as pig organs are relatively similar to us in their anatomy/physiology, which means they are perfect candidates for transplantation to humans, if we can get over the issue of rejection.
Last month, for the first time ever, a clinical trial demonstrated that it was possible to transplant an organ from a pig directly to a human. Vitally, this was done without the human’s immune system rejecting the organ immediately, as has happened in earlier trials. This surgical intervention was completed at NYU Langone Health by a team lead by Dr. Robert Montgomery, in which a pig kidney was transplanted (with familial consent) to a brain-dead patient that had signs of kidney dysfunction, before she was due to be removed from life-support. This kidney was attached to the human’s blood vessels and was kept outside of the body so that it could be better accessed. The results of this trial showed that kidney function improved in line with what a ‘normal’ transplanted kidney would. This was seen as the abnormal creatinine level of the patient (a marker of kidney dysfunction) returned to a normal level again. Alongside this, there was production of the normal amount of urine, with no signs of rejection suggesting that the kidney had functioned normally and overall had worked well.
Genetically, to produce this transplantable kidney, a certain gene was removed (i.e. knocked out) in pigs via intentional-genetic engineering. This, in turn prevents the alpha-gal sugar molecule from forming on the surface of the pigs cells. These genetically altered animals are known as GalSafe pigs, which were produced by the United Therapeutics Corp’s Revivicor. Importantly, it was thought that this carbohydrate (alpha-gal) was the driving force behind rejection of pig organs within humans. This trial suggests that, at least briefly, that removing the functionality of a certain gene reduces the chance of human rejection of a transplanted pig-kidney.
Whilst the production of these organs can have the potential to save the lives of countless people requiring organ transplants, an ethical question mark still remains on whether it is correct to rear an animal just to harvest their organs. In America, this is being addressed by a researcher (Karen Machke), who will attempt to develop ethical/policy recommendations for any clinical trials of this type. Finally, the use of GalSafe pigs in transplantation has not been limited to just kidneys; there are suggestions that alongside further kidney clinical trials, there will also be trials focusing on transplantation of heart valves and skin.
