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” transcends the traditional boundaries of life and death.
Usually, scientists think of death as Irreversible cessation of biological functions Overall, not. However, practices such as organ donation highlight that organs, tissues, and cells can continue to function after the death of an organism. This resilience raises the question: what are the mechanisms by which certain cells can continue to function after the death of an organism?
We are researchers Find out what’s going on insideAfter 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 common developmental change, there are few examples of organisms changing in ways that were not predetermined. 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.
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 sheepand 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. 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 Homeostasismoreover, 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 cellsThe insulin-producing islets in the pancreas are transplanted from the donor to the recipient, and researchers believe that autoimmune processes, high energy costs, and a deterioration of defense mechanisms may be the reasons why many islet transplants fail.
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 CircuitsThese channels and pumps generate electrical signals that allow 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, zebrafishAnd 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 perspectives.
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. Noble He is an associate professor of microbiology at the University of Washington. Alex Positkov I am the Senior Technical Leader for Bioinformatics in the Irele & Manella School of Biological Sciences at City of Hope. This article is conversation Under Creative Commons License.Please read Original article.
