Xeno-Transplantation: The Ultimate Organ FactorySome of the biggest and most important medical success stories from the second half of the 20th century involve organ transplants. However, the quantity of organs needed still outpaces the quantity supplied by a wide margin and, as the population ages, the gap will get wider still. Just consider these statistics:
- Currently, the United Network for Organ Sharing shows nearly 112,000 U.S. candidates on a waiting list for transplants. But, less than 30,000 will receive transplants this year.1
- According to the National Institutes of Health, 3,000 Americans are now waiting for fewer than 2,000 hearts that will become available this year.2
Moreover, there is no effective market mechanism for the allocation of the limited supply of organs.
One approach suggested for addressing this shortage is to increase awareness of, and participation in, organ donor programs. Unfortunately, it is estimated that this would still not provide anywhere near the number of organs needed today or the much larger number needed in the future. Evidence seems to indicate that China is executing prisoners at an accelerated pace in order to meet the organ demands of the Chinese elite, as well affluent foreigners.3
One more humane avenue thats been talked about for decades is so-called xeno-transplantion. This is the transplantation of organs and tissue from one species to another. For humans, the most likely animal donors are pigs, due to their comparable size, their rapid growth, and the physiological similarity of their organs to ours.4
A major hurdle with any transplantation, but particularly xeno-transplantion, is the rejection of organs as the result of antibodies in the recipients immune system, which attack the donated tissue. Strides have been made to overcome this problem, but other serious roadblocks remain, including incompatibilities between human and pig anti-coagulation mechanisms, and the potential presence of pathogens that can be deadly to humans, such as those that lead to mad cow disease.
Now, however, a novel new approach has been developed that would eliminate all of these problems. What is this "game-changing" new approach? Its a futuristic idea called "blastocyst complementation."
Put simply, its a technique in which the organs of one species are grown in a different, yet similar, species by injecting stem cells into embryos of the second species. Thanks to the efforts of researchers in Japan, this technique is no longer just theoretical.
Recently, scientists at the Center for Stem Cell Biology and Regenerative Medicine at the University of Tokyo have successfully engineered mice to grow rat organs. The mice had been genetically altered so they could not produce their own pancreases.
When stem cells from rats were injected into the mice embryos, they grew rat pancreases. The Japanese team believes this technique can be used to grow any type of organ in a compatible species. Professor Hiromitsu Nakauchi, director of the center, is confident well soon be able to apply this technique to produce human organs in other species.
Currently, the center is seeking permission to use human stem cells, but in the meantime, they have been able to generate human blood in pigs by injecting human blood stem cells into pig fetuses.
Understandably, this possible breakthrough is getting a lot of attention. Professor Chris Mason, Chair of Regenerative Medicine at University College London, paints an exciting scenario when he states, "For something like a kidney transplant where it is not urgent, it would be highly attractive to be able to take cells from a patient, grow them in this way, and deliver a personalized kidney."
Similarly, to treat people suffering from diabetes, human stem cells could be injected into a pig to grow a replacement pancreas.5
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However, as Mason adds, "There is [still] a long way to go before it could result in usable transplants, but it is an exciting vision." Undoubtedly, Mason is right, but for many patients, waiting for this vision to become reality is their only option.
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In light of this trend, we offer the following three forecasts for your consideration:
First, the overall cost of healthcare will be positively impacted when blastocyst complementation becomes commercially available.
Although raising donor animals will not be cheap, and this approach will involve surgical costs comparable to conventional transplants, there will be a greater savings when the costs of long-term care and treatment are reduced. Removing patients from dialysis and freeing people from the on-going costs and complications of diabetes and other maladies should yield a net drop in overall medical costs.
Second, ethical issues are certain to be raised about breeding animals simply to be used as a source of human organs.
Animal rights activists will surely go into full swing, even attempting to block research and development through the courts.
Although they have succeeded in discouraging many people from wearing fur, they will face a steeper uphill battle arguing against a program that promises to extend the length and quality of life for ailing humans. One obvious counter-argument is that we already raise animals for life-sustaining food, so it is logical to raise them for life-sustaining and life-enhancing organs.
Third, in many countries, adoption will undoubtedly be delayed by government regulations.
It will start from safety concerns, which are legitimate, since well-established procedures will need to be followed. This oversight will make procedures burdensome and costly, meaning that fewer people will benefit. This promises to open up another lucrative market for medical tourism.
References List :
1. For more information about the transplant waiting list in the U.S., visit the United Network for Organ Sharing website at: http://www.unos.org 2. To access information regarding heart transplants, visit the National Heart Lung and Blood Institute website at: http://www.nhlbi.nih.gov 3. The Guardian, August 26, 2009, “Executed Prisoners Are Main Source of Chinese Organ Donations,” by Tania Branigan. ⓒ Copyright 2009 by Guardian News and Media Limited. All rights reserved. http://www.guardian.co.uk 4. The Telegraph, June 19, 2011, “Pigs Could Grow Human Organs in Stem Cell Breakthrough,” by Richard Gray. ⓒ Copyright 2011 by Telegraph Media Group Limited. All rights reserved. http://www.telegraph.co.uk 5. Ibid.
