Pig stem cells offer renewed hope of GM organ transplants

A Chinese research team has brought the quest for a genetically modified pig, capable of providing viable organs for transplant patients, a step closer. Scientists at the Shanghai Institute of Biochemistry and Cell Biology (SIBCB) have succeeded in creating the first pig stem cells in the laboratory, the Journal of Molecular and Cell Biology reports. These cells could be used to create 'transgenic' pigs, which have been genetically altered so that their organs would not be rejected by the human immune system. Once created, such pigs could potentially help scientists to cheaply produce an almost limitless supply of organs for use in humans. The breakthrough also paves the way for research into human diseases using pigs as models, and for improved pig immunity and animal farming.

To create transgenic animals, scientists first introduce the required genetic changes into embryonic stem cells (ES cells) . Many different strains of genetically altered mice have been created in this way, but researchers have never managed to obtain ES cells from pigs. This has held back research into the possible use of transgenic pigs to address the shortage of human organs available for transplant. The Chinese researchers therefore decided to try and create an alternative to pig ES cells. Using the iPS (induced pluripotent stem) cell technique, which uses viruses to introduce key embryo development genes, the team reprogrammed adult cells taken from a pig's ear and bone marrow into embryonic-like stem cells.

'Scientists have been trying to do this for quarter of a century', said Dr Lei Xiao, lead author of the study. He hopes that pigs can now be modified so that their organs will not be rejected by human immune systems. 'The pig species is significantly similar to humans in its form and function, and the organ dimensions are similar to human organs. We could use embryonic stem cells or induced stem cells to modify the immune-related genes in the pig to make the pig organ compatible to the human immune system'.

Professor Chris Mason, a regenerative medicine expert at University College London (UCL), hailed the breakthrough as a 'major step change in the treatment of organ failure, which potentially could deliver real benefit to millions of patients within a decade'.

Not everyone has been as enthusiastic, however. Dr Sebastien Farnaud, science director of the Dr Hadwen Trust for Humane Research (HTHR), argues that the implications of this kind of research is 'highly speculative' and that the use of sentient animals 'as little more that living organ grow-bags, is not only ethically unsupportable but also scientifically dubious'. He cautions that the creation of pig stem cells will not necessarily remove the risk of organ rejection by humans, but more worryingly, introduces the 'risk of infecting patients and the wider public with pig viruses'.