Thursday, the Scottish-based company PPL Therapeutics Plc said it produced five "knockout" piglets - so-called because their genes have been modified to reduce to chance of their organs being rejected by human hosts could bring the prospect of transplants from animals a step nearer.
But company's lead in the field of xenotransplantation, or animal-to-human transplants, may be short-lived as rival research groups prepare to detail similar successes.
Other biotechnology companies working in the field include U.S.-based Immerge BioTherapeutics Inc., a joint venture between Swiss pharmaceutical giant Novartis AG and Nasdaq-listed BioTransplant Inc., which has been working on miniature pigs.
Pig kidneys, hearts and other organs could help solve a shortage of donated human tissue. In the U.S. alone there are some 75,000 people currently awaiting organs, 16 of whom die each day. Pigs are viewed as the most suitable animals for providing organs for transplant into humans because their organs are of a similar size.
For the industry, the potential payoff is huge. Billions could be made from a safe system for transplants that could help treat patients of ailments including heart disease, diabetes and neurodegenerative conditions like Parkinson's and Alzheimer's.
The Scottish company, which hopes to start clinical trials on human subjects within four years, said the market for such organs could be worth $5 billion a year. Cell therapies based on pig tissue may add another $6 billion. The company's shares jumped in reaction to this week's announcement.
Ian Smith, a biotechnology analyst at Lehman Brothers, said xenotransplantation could represent a "massive step forward" in relieving the current shortage of suitable organs.
"But there are a number of serious issues, including the possibility of introducing pathological viruses into humans. The risk from viruses is an unanswered question - and it won't be answered until you have had organs transplanted into humans over many years," he said.
The idea of using animal organs in human operations is also likely to trigger a fierce ethical debate. Sarah Kite, research and information director at the British Union for the Abolition of Vivisection, said xenotransplantation research caused "unacceptable suffering" to sentient animals.
"Not only do we question the right to genetically engineer animals to use as spare parts, we also believe that the science of xeno is so poorly developed that clinical trials cannot reasonably be considered," she said.
The Scottish company, however, says the successful cloning of "knockout" pigs has removed a key obstacle in the development of xenotransplantation. Its pigs have had one gene "knocked out" - the alpha 1,3 galactosyl transferase gene. This gene creates an enzyme that the human immune system rejects as foreign.
Other genes thought to binvolved in the body's rejection of foreign tissue are also being studied as potential targets to be switched off.
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