"Sheep personal face": technical obstacles more ethical cut to the heart

  In the United States, about 76,000 people or even longer waiting for an organ transplant, the data in the UK is 6,500, and each patient may have to wait five years。 A daily average of 32 patients die while waiting for an organ donation in。   Prior to that, although scientists have successfully cultivated a man-pig chimeras, the medical community is excited about using them to cultivate human organs, but did not study team will further promote this outcome。
Although scientists can not get organs from pigs or sheep and transplanted into the human body, but they believe that human stem cells may be one way to solve the problem。   University of California, Davis zoologist Pablo Ross (PabloRoss) who took part in the sheep chimera research, he insisted that this was one of exploration currently promising in medicine。
  As we all know, organ transplant rejection problem has not yet solved, organ transplant recipients need long-term taking anti-rejection drugs to reduce the immune system attacks the transplanted organ。 A pleasant surprise is that the use of human – animal chimeras get the organ, I carry a specific immune antigen, can reduce this rejection to a large extent。   According to reports, the project provides the possibility for the treatment of other diseases such as type 1 diabetes。 "We use animal chimeras of this technology, in rats successfully bred a mature mouse pancreas and pancreas transplant this to type 1 diabetes in mice。 After transplantation, blood glucose regulation will tend to normal mice。 "The project leader, professor of genetics at Stanford University in Nei Boshi (HiroNakuachi) last month at the annual meeting of the American Association, said the scientific development。   Ethical controversy worried human brain cells into experimental animals Interestingly, more than a year before, the US government has said that such controversial experiments will provide funding, but then after receiving the animal rights groups from more than twenty thousand times the complaint, and withdrew funds。
  Disputes including fears there will be the traditional image of "human sheep body" or "goat face personal" weird image。   The face of controversy, in Neibo Shi said in a report: "We created the embryo experiment after 28 days was destroyed。
"In fact, in recent years, stem cells and genetic engineering to produce chimeras pave the way for different species, scientists hope to foster greater chimeric animals, such as sheep or pigs with human organs。   However, it is facing serious technical obstacles and complex ethical issues。 US researcher Dr. Stowers Institute for Medical Science and Technology Daily Liling Heng told reporters that people do not want chimeric animals after someone germ cells and nerve cells, especially the brain from human chimeras can not, therefore, reproductive cells and nerve cells human – animal chimeras ethical boundaries。   Pablo Ross admitted that he also has similar concerns。
  Currently experiments in human cells only in the chimera of less than 1%, if the ultimate goal is to meet the needs of human organ transplantation, it is necessary to gradually increase the proportion of chimera in human cells, and this process will inevitably lead to more many ethical issues。   Ross said that everything depends on human cells in vivo activity of the extent to achieve。 If they are expected to be far larger than the diffusion, such as going into the brains of experimental animals, that for ethical reasons, want to authorize such a test can not be estimated。   "If these cells during development, not just fitting to the anticipated organs to go, but to participate in the development of other organs, such as the nervous system or the reproductive system, this time will bring a very complex ethical issues this is everyone worried about the main reason for such research。 "Liu Zhonghua also think。   Therefore, Liu Zhonghua stressed that how to control these cells, not toward the people do not want it to go in the direction of organ development, is one of the key researchers need to think about current research and。   According to Liu Zhonghua grasp of the situation, it has not yet introduced management policies and animal chimeric embryos specifically for the development of life in China。
  "However, units where researchers have ethics committees prior to carry out research and development between man and animal chimeric embryos, are required to report the filing and approval of the Ethics Committee。 Only after review by the ethics committee, to be able to carry out related work。 Therefore, although no one in our country up to the policy level, but within the management system is very strict。
"Said Liu Zhonghua。   The distance but also the practical application of technology can really break through the barrier in American science Development Association annual meeting, in Neibo Shi said: "This technology will be applied to humans may also need 5 Year – 10 years, but we will wait until the maturity of this technology one day。 "As the person in charge of China's first use of adult somatic cloning as a nuclear donor cells Min pig project, Liu Zhonghua frankly, from a practical standpoint, this technology is widely recognized route of academia, but in practice, people animal embryo cells in the proportion is not very high, the actual application from a long distance。   Liu Zhonghua said that at present the research work faces many difficulties, first is how to increase the proportion of human cells occupied by animals in the process of embryonic development and control its fate。
  "Because the ultimate goal of the study is to cultivate human organs in vivo animal or human cells is the main organ, the proportion of human cells share of this organ is critical parameters, from the current case reports can be seen, this ratio is not high。 "Said Liu Zhonghua。   Neibo Shi research in human stem cells are introduced into the group of sheep embryos, both formed chimera。
And the experiment income people – sheep hybrid animals, human cells are very small contribution, almost 99% of the gene from sheep embryos, in which human cells only about 10,000 (or less)。 Liu Zhonghua, said Stanford University scientist who first bred sheep chimera, compared to the previous research has a very big breakthrough, but it can also be seen from the results, from the practical application of this work is still a long way to go。   Liu Zhonghua believe that the study also faces second difficulty is that to control cells, the current design is the original idea of an animal embryo in a certain key gene control organ development knocking to get rid of, so the animals themselves would be no way out of this development organ。
  "For example, pancreas, sheep or pig-related gene knock away, and it is impossible pancreas from animal embryos, that is, sheep or pigs own cells developed from embryonic, this child is equivalent to the emergence of a vacancy, the vacancy in accordance with the theoretical design, will move into the human embryonic stem cells are filled, so that it is possible to grow cells to develop into a human pancreatic。 "Said Liu Zhonghua。
  Technical difficulties need to break still discuss ethical issues can not be separated, Liu Zhonghua that, first, by exploring how technology and theory, to increase the proportion of human cells in which such chimeric embryo participatory process; secondly, how to effectively control it is hoped that the cells towards the direction of its development of organ development, without participating in those organs, people do not want development, these are the problems to be solved。   "Of course, in order to produce human organ transplant donor organ is the target point of view, by no means limited to these two issues, related with the progress of the work must also meet other unforeseen problems。 "Liu Zhonghua representation。

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