In addition, instead of monkey or humans – cows have been cloned. Evidence of severe pregnancy complications and defects caused by cloning have been widely reported by the cattle cloners. There have been instances of dramatically oversized calves, enlarged tongues, intestinal blockages, immune deficiencies and diabetes.
Cows aren’t the only animals that there have been problems with. Dolly the sheep has developed arthritis but scientists are not sure whether it is due to cloning or not. They think that it is strange that arthritis would develop in a sheep at the young age of five and a half years. And then another problem surfaced, which suggested that cloning could be to blame. The Scottish researchers, who cloned Dolly, have discovered that her cells are six years older than her chronological age. The cell that was used to fertilise the sheep ovum that became Dolly came from an adult female sheep, aged 6 years. Apparently, cells have an internal mechanism, which keeps track of its age. This mechanism was not set back to 0 when Dolly was conceived. She was, in essence, over 6 years old when she was born. So Dolly is in fact 11 and a half years older so the cloning could have caused the arthritis. All of this gives cause for concern.
Another clone, which is not so famous, is Xena the pig. Xena’s name highlights one hope for the future of pig cloning – the use of these animals in xenotransplantation, where pigs would be donors of genetically modified organs for transplants in humans.
The female piglet was cloned by microinjecting genetic material from fetal pig skin cells into eggs stripped of their own genetic material. A needle-like pipette used in the microinjection works like a tiny needle gun firing into the egg in a controlled and rapid motion. The method only transfers genetic material from the fetal donor cell. By comparison, the method used to clone Dolly the sheep fuses together the entire donor cell containing the genetic material and the empty egg. After stimulating the injected eggs with an electrical pulse and allowing them to mature into early stage embryos, the researchers transplanted the embryos into four surrogate mothers. Out of the 18 eggs implanted, only two were born and Xena is the only surviving piglet.
Not all cloning has been bad news though. The latest animals to be cloned are the piglets. The pig-to-human transplants have moved a step closer after scientists produced five piglets genetically modified to provide organs for human patients. Scottish based firm PPL Therapeutics said it produced five healthy “knock-out” piglets, born on Christmas day. They are so called because a gene, which causes the human immune system to reject pig organs within minutes of transplantation has been “knocked out” of their genetic make up. Scientists at PPL, which was behind the cloning of Dolly the sheep, have found a way to inactivate the alpha 1.3-galctosyl transferase gene. The piglets’ birth is a major step towards successful xenotransplantation – the transfer of cells or organs from one species to another. With one of the major technical hurdles and scientific risks overcome, the promise of xenotransplantation is now a reality, with the potential to revolutionise the transplant industry. The technology could also be extended to include the potential transplant of cells to patients suffering from diseases such as Parkinson’s, Alzheimer’s and diabetes.
Cloning of these animals took place in the lab, following which the fertilized eggs were put back inside the mother pig who gave birth. If the pigs are bred for organs, we could effectively have a continual supply without the rather alarming use of human cloning for organ harvesting. Despite this cloning needs to be approached with great caution.
Society is opposed to xenotransplantation from a public health point of view, from a moral point of view, and from an animal cruelty point of view. The strongest argument against it is still the threat of transmission of known and unknown viruses. It only needs one successful transmission of a disease-causing virus from an animal to man to start an epidemic. Viruses, which are not dangerous in pigs, can become dangerous in humans.
Some experts caution that the whole field of xenotransplantation is fraught with infection risks, both to the transplant recipients and, perhaps, to other humans as well.
Pigs are known to contain what are called porcine endogenous retroviruses or PERVs - viruses that evolved with the swine over millions of years and now are part of the animals’ genes.
The viruses do not affect the pig, but what would happen if the animal’s organs are transplanted into humans? Perhaps nothing, or perhaps it could lead to a completely new disease, say some experts.
Alix Fano, head of the Campaign for Responsible Transplantation, thinks, “This is a recipe for disaster as pigs are a reservoir of viruses and we have no idea what their organs would do if transferred to humans.”
Some studies in which humans were exposed to pig cells have suggested that PERVs do not infect human cells. Nevertheless, critics say there are many other examples showing that some retroviruses that are harmless in one species become virulent killers when transplanted into other humans.
One of the most notable examples is HIV, the virus that causes AIDS. The retrovirus is thought, by some, to have lived harmlessly in the green monkey and became deadly only when it jumped to humans.
Jonathan Allan of the Southwest Foundation for Biomedical Research said studies have shown that a virus that was a harmless part of the genes of the langur monkey became a serious pathogen when it infected the Rhesus monkey.
Before pigs can be considered for the source of human organs, he said, much research will be needed to develop a level of confidence that the viral risk has been settled.
“The science of xenotransplantation needs to go forward,” said Allan, “but it is important to resolve this infection risk.”
The issue is very difficult, he said, because researchers will need to answer basic questions about the virus threat: Will it infect the recipient? If so, can it be transmitted to other people? Can it be passed to a new generation?
Allan said the research is particular complex because some viruses are known to hibernate in the body for years before bursting into infection. Therefore, it would be like a time bomb that may or may not go off.
Even if the complex scientific questions are answered, many people will find disgusting the whole idea of pig organs being transplanted into humans.
So, in conclusion, I feel that cloning of humans is morally wrong and that a law should be passed to ban these type of experiments and it has been done in America, with a ten year jail sentence and a 1 million dollar fine. However, scientists will move to where it is still legal and already one of the leading US scientists has moved to Britain to continue his studies and research.
