In science fiction films like 'Frankenstein' and 'Re-Animator', human bodies come back to life, existing in a strange state between life and death. While this sounds like the stuff of fantasy, a new study says a 'third state' exists in modern biology, between life and death.
"Surprisingly, after the death of the organism, its cells acquire new abilities that they did not have when they were alive", say biologists.
The new study in Physiology was led by Professor Peter Noble at the University of Washington in Seattle and Alex Pozhitkov at City of Hope National Medical Center, Duarte California.
"Life and death are traditionally seen as opposites," they say.
But the emergence of new multicellular life forms from the cells of a dead organism represents a 'third state' that extends beyond the traditional boundaries of life and death.
'Some cells - when provided with nutrients, oxygen, bioelectricity or biochemical signals - have the ability to transform into multicellular organisms with new functions after death.'
The team conducted a review of recent studies investigating the remarkable ability of cells to exist in new forms after an organism dies.
Scientists discovered that human lung cells can self-assemble into miniature multicellular organisms that can move around - called 'anthrobots'.
These anthropots can not only navigate their environment, but also repair themselves and nearby damaged nerve cells.
The team says these are examples of new cell functions that do not exist in living life, let alone in death.
How some cells function in the third state after an organism dies remains unclear, but one possible Frankenstein-style explanation is a hidden system of 'electrical circuits' that revive cells.
Several factors can affect which cells have this ability, including environmental conditions (such as temperature) and energy sources.
'Metabolic activity plays an important role if cells can continue to survive and function,' added the research team.
Factors such as age, health, sex and species type also 'shape the landscape after death' – always, if they can exist in the third state.
Ultimately, the research hints at the 'unexplored frontiers' that could bring animal cells to the third state.
This research has the potential to transform regenerative medicine, redefine legal death, and provide insight into the physiological limits of life.
