US researchers have found tissue decay after death can be halted and cell functions in organs restored based on early experiments in pigs, a development that is not yet clinically useful but could eventually aid human organ transplantation.
One hour after stopping the anaesthetised pigs' hearts, Yale University researchers were able to restart circulation using a specialised machine and a synthetic fluid carrying oxygen and other components that promote cellular health and suppress inflammation.
Six hours later, the process, known as OrganEx, had reduced or corrected some of the tissue damage, such as organ swelling and collapse of blood vessels, that typically results from a lack of oxygen caused by cardiac arrest.
During the entire experiment, the pigs had no evidence of electrical activity in the brain, the researchers said.
The results show that when the heart stops, the body is "not as dead as we previously assumed", Yale's Zvonimir Vrselja said at a press briefing.
"We were able to show that we can persuade cells not to die," he said.
Genetic analysis of the tissues suggested that molecular and cellular repair processes began in the pigs once circulation was restored, the researchers reported in the journal Nature.
Compared with traditional means of restoring circulation, which can cause stress and damage to cells, the new process "preserved tissue integrity, decreased cell death and restored selected molecular and cellular processes across multiple vital organs", the researchers wrote.
Live-saving speculation 'a bit fantastical'
Dr Nathan Emmerich, a senior lecturer in bioethics at the Australian National University College of Health & Medicine, said the study was interesting, but presenting the process as pushing back the boundaries of death was taking things a little far.
"The idea that this will become a new CPR is a bit fantastical," he said.
"But there could be some circumstances in which this could be useful [well in the future]. It might be another tool in an ICU doctor's toolkit, the same way we use life support, and certainly there's organ donation."
Dr Emmerich said humans tended to have a baked-in assumption that there was a single point in time when someone changes from alive to dead — "when the soul leaves the body" — but the reality of death was more complicated.
"Biology doesn't really believe in souls," he said.
"A biological concept of death is more about homeostasis, which is about the functions a body or organism does that keep it in the same state over time. Cell function, cell dying, the creation of new cells — that's all part of that process.
"From a biological point of view, if someone is brain dead, the body does continue to engage in some of these functions and very quickly ceases due to the lack of circulation. If you can restart circulation, these processes seem to continue."
The Yale researchers do hope their discovery will eventually enable the increased use for transplantation of organs retrieved after withdrawal of life support in donors with severe, irreversible brain injuries, by preventing the damage that ensues when blood stops circulating.
Currently, these organs do worse after transplant than those procured from brain-dead donors who remain on life support.
Progress on this front using the new process could be years away, however.
The pig study result "stops far short of saying that any organs were restored to the level of function" necessary to support life, said Stephen Latham of Yale's Interdisciplinary Center for Bioethics.
Theoretically, the technology could some day be used to restore life in someone who had just died. But in order to do that, "there's a great deal more experimentation that would be required", Dr Latham said.
"And you'd have to think about what is the state to which a human being would be restored."
Reuters/ABC
