Scientists Studied Life After Death, Here’s What They Found

Death has always been seen standing in stark opposition to life, yet new groundbreaking research may shift this understanding. Scientists are diving into a mysterious biological phenomenon known as the “third state.” This is a state in which cells from dead organisms can reorganize into new multicellular life forms with alternative functions they never had while alive. Researchers at the University of Alabama, Birmingham, and City of Hope Cancer Center documented this phenomenon in a 2024 study published in the journal Physiology.

Death is usually a definitive, irreversible cessation of an organism’s overall function; however, certain cells take on a new meaning to “life” and even transform after death occurs. Peter Noble, a microbiologist at the University of Alabama Birmingham, told The Conversation that this third state suggests that organismal death may play a significant role in how life transforms over time.

Organ donation practices demonstrate that individual cells, tissues, and organs can remain functional, even after an organism dies. The question researchers raised centered on the mechanisms that enable this post-mortem functionality. A published review by researchers states that when specific conditions involving oxygen, nutrients, bioelectricity, or biochemical signals are met, cells can reorganize into entirely new multicellular entities with entirely new functions.

Xenobots Emerge from Frog Cells

Some developmental transformations follow a familiar, predetermined program, such as caterpillars metamorphosing into butterflies. However, in other cases, cells actively undergo changes that do not follow a predetermined path. Tumors, HeLa cells, and organoids do not develop new functions and therefore do not fall under this group. 

Skin cells taken from deceased frog embryos displayed remarkable adaptability when researchers at Tufts University, the University of Vermont, and Harvard’s Wyss Institute placed them in a petri dish. These cells spontaneously self-organized into multicellular constructs termed xenobots. It is named after the African clawed frog species Xenopus, from which it originated.

Unlike their original biological role in frog embryos, xenobots employed their cilia for locomotion rather than mucus movement. Cilia are tiny, hair-like structures that normally help move substances across tissue surfaces. Michael Levin, a developmental biologist at Tufts University who led the research, told the Harvard Gazette that these cells have a frog’s genome but are not forced to become tadpoles. He stated that the cells use their collective intelligence to do something amazing.

Xenobots demonstrated kinematic self-replication, a process in which they reproduce their form and function without undergoing growth. As the xenobots moved through their environment, they gathered loose frog cells into spheres, which then coalesced into new xenobots. These new generations could then repeat the process. Joshua Bongard, a computer scientist and robotics expert at the University of Vermont who co-led the research, told the university’s communications team that, with the right design, xenobots will, at random, self-replicate.

Human Cells Form Anthrobots

Isolated human lung cells demonstrated similar capabilities. Researchers at Tufts University discovered that tracheal cells from adult human donors could self-assemble into new multicellular constructs known as anthrobots. Gizem Gumuskaya, the graduate student who created the anthrobots, told Harvard’s Wyss Institute that, unlike xenobots, anthrobots do not require tweezers or scalpels to shape them, and that researchers can use adult cells instead of embryonic cells.

Each anthrobot begins as a single cell derived from an adult donor. The cells lining the trachea surface are covered with hairlike projections called cilia that beat back and forth. When grown in a lab using a three-dimensional scaffold made from rat tissue, the cells spontaneously form tiny multicellular spheres called organoids after approximately 14 days.

Initially, the cilia faced inward on these organoids, rendering them useless for locomotion. Researchers developed growth conditions that encouraged the cilia to face outward. When immersed in a special bath with different liquid properties, the cells turned their cilia outward, enabling the anthrobots to propel themselves through their environment. 

Anthrobots Demonstrate Healing Capabilities

The research team created a lab test to examine how anthrobots might heal wounds. They grew a two-dimensional layer of neurons derived from neural stem cells and created an open “wound” by scratching the layer with a thin metal rod.

When clusters of anthrobots were added to the scratched neural tissue, the organoids moved onto and down the scratch. Gumuskaya observed that a bridge of nerve tissue formed across the scratch where the anthrobots settled, healing the injury. Neurons did not grow in wounds where anthrobots were absent. Nonliving substances such as starch or silicone had no effect on the scratch, according to Levin’s statements to Science magazine.

The exact mechanism behind this regrowth remains unknown. However, Levin suggested to Science that, as living tissue, the anthrobots helped nerve cells on one side of the scratch sense where the other side was, enabling them to initiate new growth. The repaired areas displayed the same cellular density as undamaged parts of the neural layer.

The findings, published in November 2023, demonstrated that anthrobots could serve as therapeutic tools. Researchers are exploring applications including clearing plaque buildup in the arteries of atherosclerosis patients, delivering drugs to targeted tissues, and removing excess mucus in patients with cystic fibrosis.

How Long Cells Survive After Death

The duration of cellular survival after an organism’s death depends on multiple factors, including environmental conditions, metabolic activity, and cell type. Studies have documented varying survival times across different cellular systems.

In humans, white blood cells can persist for up to 86 hours after death. Research published in 1993 by C.J. Babapulle examined cadaveric blood and found that identifiable lymphocytes disappeared completely approximately 84 hours after death. Different types of white blood cells degenerated at different rates. Eosinophils and monocytes disappeared first by 60 hours, followed by neutrophils by 66 hours, and finally lymphocytes at 84 hours.

A 2012 study published in Nature Communications reported that skeletal muscle stem cells demonstrated even greater resilience. The report showed that researchers can isolate viable, functional skeletal myogenic cells from human tissue up to $17$17 days after death and from mouse tissue up to $14$14 days after death. Moreover, the research revealed that postmortem tissue preferentially enriches satellite cells, which are the stem cells that drive muscle regeneration, compared with other cell types.

Fibroblast cells from sheep and goats have been cultured successfully even longer. Research published in Fortune Journals in 2024 demonstrated recovery of live and proliferative cells from refrigerated sheep skin up to 65 days after animal death. The study represented the first report of recovering proliferative cells from mammalian tissues for an extended period exceeding 2 months postmortem.

Factors Influencing Postmortem Cellular Survival

Metabolic activity plays a crucial role in determining whether cells continue to function after death. Cells with high energy demands struggle to survive when nutrient and oxygen supplies cease, whereas those with lower energy requirements are more likely to persist.

Studies have shown that stress-related and immune-related genes experience heightened activity following death, possibly as a compensatory response to the loss of homeostasis. A 2017 study by Alexander Pozhitkov and colleagues traced gene transcripts after organismal death in both mice and zebrafish. In mice, 515 genes remained active up to 24 hours postmortem, whereas in zebrafish, 548 genes remained active up to 96 hours postmortem.

The activated genes included those involved in stress response, immune function, inflammation, and apoptosis. In both organisms, stress response genes such as heat shock proteins and hypoxia-related genes increased in abundance within the first hour postmortem. Immune response genes showed similar rapid activation, with 14 of 16 immune genes in mice increasing within an hour after death.

Environmental conditions significantly impact cellular viability. The 2012 satellite cell study found that cells maintained in anoxic conditions without oxygen lost only 29% of their population after four days at 4°C, compared with 82% loss in normal oxygen conditions. Refrigeration at 4°C extended survival times across multiple cell types compared with room temperature storage.

Additional variables influencing postmortem cellular behavior include age, health status, sex, species type, trauma, infection, and time elapsed since death. These factors interact in complex ways to determine how long specific cells can persist and whether they retain functionality.

The Mechanism Behind Cellular Reorganization

The precise mechanisms by which certain cells persist and reorganize after death remain unclear. However, one leading hypothesis suggests that specialized membrane channels and pumps act as intricate electrical circuits. These channels generate signals that facilitate communication, growth, and movement within cellular structures.

Research has demonstrated that bioelectric signaling occurs across all tissues, not just neural tissue. Levin’s work has shown that cells communicate electrically by forming networks that set their resting potential via ion channels and pumps, then dynamically exchange those states via gated electrical synapses known as gap junctions. In xenobots, calcium signaling networks enable cell coordination despite the absence of a nervous system.

Noble and Pozhitkov wrote in The Conversation that the inherent plasticity of cellular systems challenges the idea that cells and organisms can evolve only in predetermined ways. Unlike preprogrammed developmental pathways seen in nature, such as a caterpillar transforming into a butterfly, cells in the third state exhibit autonomy in their organization and functionality. Their ability to adapt to new environments and perform roles beyond their initial biological purpose suggests that the boundaries of cellular potential are more fluid than previously believed.

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Medical and Therapeutic Implications

The discovery of the third state extends beyond theoretical biology, offering potential advancements in medicine and biotechnology. Anthrobots derived from an individual’s own tissue could serve as highly effective drug delivery vehicles, minimizing the risk of immune rejection since they originate from the patient’s cells.

In medical applications, engineered anthrobots could be programmed to remove arterial plaque in patients with atherosclerosis or clear excess mucus in individuals with cystic fibrosis. The ability to use a patient’s own cells eliminates concerns about immune system responses that often complicate treatments involving foreign biological materials.

These multicellular constructs possess a natural lifespan, degrading within four to six weeks. Research published in 2023 documented that anthrobots live for 45 to 60 days before safely degrading into unviable debris. This built-in “kill switch” helps prevent uncontrolled cell growth, ensuring the biobots remain safe for medical use.

Researchers also envision applications in repairing spinal cord or retinal nerve damage, recognizing bacteria or cancer cells, and assisting in tissue regeneration. The anthrobots’ demonstrated ability to heal neural tissue in laboratory conditions suggests broader regenerative potential that could transform approaches to treating degenerative conditions and injuries.

Understanding how certain cells defy death and reorganize into functional multicellular entities holds promise for personalized and regenerative medicine. The study of this third state continues to reveal new dimensions of cellular adaptability, blurring the line between life and death. As scientific exploration advances, the potential for unlocking transformative medical innovations becomes increasingly evident.

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