Life and death have traditionally been thought of as mutually exclusive. However, the emergence of new multicellular organisms from the cells of dead organisms is aThe third state“It goes beyond the traditional boundaries of life and death.”
Usually, scientists think of death as Irreversible cessation of biological functions Overall, no, but practices such as organ donation highlight the possibility that organs, tissues, and cells may continue to function after an organism dies.
This resilience raises the question: By what mechanisms do certain cells continue to function after an organism dies?
We are researchers Find out what’s going on inside After the organism diesOur Recently Published ReviewsIt explains how certain cells function when provided with nutrients, oxygen, bioelectrical, and biochemical stimuli. Change into a multicellular organism Even after death, it has new functions.
Life, death and the emergence of the new
The third condition calls into question the way scientists usually understand cell behavior: While a caterpillar metamorphosing into a butterfly or a tadpole evolving into a frog may be a well-known developmental transition, there are few examples of organisms changing in ways that are not predetermined.
tumor, Organoids A cell line that can divide indefinitely in a petri dish, e.g. HeLa cellsis not considered part of the third state because it does not develop new features.
But the researchers found that skin cells extracted from dead frog embryos were able to adapt to their new environment in a petri dish in the lab and spontaneously reorganize into multicellular organisms. They’re called Xenobots..
These organisms have demonstrated behaviors that go far beyond their original biological roles: Specifically, these xenobots use cilia (tiny hair-like structures) to navigate their environment, whereas in living frog embryos, cilia are typically used to move through mucus.
frameborder=”0″ allowfullscreen=”allowfullscreen”>
The Xenobots are Kinematic self-replicationThis means they can physically replicate their structure and function without growing, unlike the more typical replication process that involves growth within or on an organism.
The researchers also found that single human lung cells could self-assemble into small, multicellular organisms that could move around. These robots They behave and structure themselves in new ways: they are not only able to navigate their surroundings, but also to repair both themselves and damaged neuronal cells nearby.
Taken together, these findings demonstrate the inherent plasticity of cellular systems and call into question the idea that cells and organisms can only evolve in predetermined ways. The third state suggests that the death of an organism may play an important role in how life changes over time.
State after death
Several factors influence Whether certain cells and tissues can survive and function after an organism dies. This includes environmental conditions, metabolic activity, and preservation techniques.
The survival time varies depending on the type of cell. For example, in humans, White blood cells Death occurs within 60 to 86 hours after the death of the organism. Skeletal muscle cells Regenerates 14 days after death, but fibroblasts From sheep and goat They can be cultured up to one month after death.
Metabolic activity plays a key role in whether cells survive and continue to function. Active Cells Cells that require a continuous and large supply of energy to maintain function are more difficult to culture than cells with lower energy requirements.
Preservation techniques Freezing and storage Tissue samples such as bone marrow can function similarly to tissue samples from living donors.
Inherent survival mechanisms They also play an important role in whether cells and tissues remain viable. For example, researchers Stress-related and immune-related genes After the death of an organism, perhaps to compensate for losses Homeostasis.
In addition, the following factors trauma, infection and Time since death This has a significant impact on tissue and cell viability.
Factors such as age, health, sex and species type further shape the post-mortem situation, as seen in the challenges of culture and transplantation. Metabolically active pancreatic islet cellsInsulin-producing pancreas is transplanted from the donor to the recipient.
Researchers believe that autoimmune processes, high energy costs, and deterioration of protective mechanisms may be responsible for the failure of many islet transplants.
It is unclear how the interplay of these variables allows certain cells to continue functioning after an organism dies. One hypothesis is that specialized channels and pumps embedded in the cell’s outer membrane allow them to continue functioning after an organism dies. Complex Electrical Circuits.
These channels and pumps generate electrical signals that enable cells to communicate with each other and carry out specific functions, such as growth and movement, and shape the structures of the organisms they form.
It is unclear to what extent different cell types undergo changes after death. Previous studies have suggested that stress, immune, and Epigenetic Regulation Activated after death Mouse, zebrafish And peopleThis suggests a broad potential for transformation across diverse cell types.
Impact on biology and medicine
The third state not only provides new insights into cellular adaptability but also offers new therapeutic prospects.
for example, Potential source of robots Proteins taken from human tissue could be used to deliver drugs without triggering unwanted immune responses, and synthetic robots injected into the body could potentially dissolve arterial plaque in people with atherosclerosis and remove excess mucus in those with cystic fibrosis.
Importantly, these multicellular organisms have a lifespan after which they decompose naturally. 4–6 weeksThis “kill switch” prevents potentially invading cells from multiplying.
A deeper understanding of how some cells continue to function and transform into multicellular organisms long after an organism’s death could lead to advances in personalized and preventive medicine.
Peter A. NobleAssociate Professor of Microbiology, University of Washington and Alex PositkovSenior Technical Leader, Bioinformatics City of Hope’s Irele & Manella Graduate School of Biological Sciences
This article is reprinted from conversation Published under a Creative Commons license. Original article.
