For years, life and death have been seen as opposite forces. Yet, recent discoveries reveal a "third state" beyond these boundaries. This phenomenon involves new multicellular life forms arising from cells of deceased organisms. These findings challenge long-standing perceptions about life and death, offering new insights into cellular behaviour.

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Defining the Third State

Typically, death is understood as the irreversible halt of an organism’s functions. Yet, certain cells, like those used in organ donation, continue to work post-mortem. This raises intriguing questions: how do some cells survive after death, and what mechanisms enable this?

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Researchers are now investigating these post-mortem transformations. In a recent study, they observed how some cells, given the right conditions, transform into new life forms. These cells, once provided with nutrients, oxygen, or bioelectricity, can reorganise into multicellular structures. These new entities perform functions never associated with their original biological roles.

Example of Xenobots

A notable example of this "third state" involves frog embryo cells. Scientists extracted skin cells from deceased frogs and placed them in a lab dish. To their surprise, these cells reorganised into new multicellular organisms, known as xenobots. These xenobots, far from their original purpose, used cilia for navigation, a feature previously meant for moving mucus in frogs.

Diagram A depicts an anthrobot constructing a bridge over a damaged neuron, spanning three days. Diagram B illustrates the 'stitch' in green at the conclusion of Day 3. (Image: Gumuskaya et al. 2023/Advanced Science, CC BY-SA)

Unlike traditional replication, xenobots replicate without growing. They perform kinematic self-replication, meaning they physically rebuild their structure. Another fascinating discovery involves human lung cells. When placed in lab conditions, these cells self-assembled into tiny organisms capable of movement and self-repair.
Factors Influencing Cell Survival Several factors affect whether cells survive post-death. Environmental conditions, metabolic activity, and preservation techniques play crucial roles. For instance, in humans, white blood cells die around 60 hours post-mortem, while mouse skeletal cells can survive for up to 14 days. Preservation methods like cryopreservation also allow certain tissues, like bone marrow, to continue functioning as living cells would.
Understanding the survival mechanisms of these cells offers hope for future advancements in personalised medicine. Although many factors remain uncertain, ongoing research holds promise in revealing the mystery of life after death.