Researchers Study Life After Death — And It Gets Weirder

Life and death are commonly regarded as contrasting concepts. Nonetheless, the appearance of novel multicellular life forms originating from the cells of a deceased organism presents a " third state that exists outside the conventional limits of life and death.

Typically, scientists view death as the permanent cessation of the operation of an organism Overall, however, practices like organ donation demonstrate that organs, tissues, and cells can still operate effectively even following an organism's death. This durability prompts the inquiry: What processes enable specific cells to remain functional post-mortem?

We are researchers who investigate what happens within organisms after they die . In our recently published review , we explain that specific cells—when supplied with nutrients, oxygen, bioelectricity, or biochemical signals—possess the ability to transform into multicellular organisms with new features following demise.

Existence, cessation, and appearance of fresh beginnings

The third state poses a challenge to conventional scientific understanding of cellular behavior. Although we are accustomed to well-known developmental changes like those seen during caterpillar-to-butterfly transformation or tadpole-to-frog development, there are limited examples of organisms altering themselves in non-predestined manners. Tumors provide such an example. organoids , and cell lines capable of dividing endlessly in a petri dish, such as HeLa cells They are not regarded as part of the third state since they do not acquire new functionalities.

However, researchers found that skin cells extracted from deceased frog embryos were able to adapt to the new conditions of a petri dish in a lab, spontaneously reorganizing into multicellular organisms called xenobots . These organisms exhibited behaviors that extend far beyond their original biological roles. Specifically, these xenobots use their cilia — small, hair-like structures — to navigate and move through their surroundings, whereas in a living frog embryo, cilia are typically used to move mucus.

Xenobots are also able to perform kinematic self-replication , meaning they can physically replicate their structure and function without growing. This differs from more common replication processes that involve growth within or on the organism’s body.

Scientists have discovered that individual human lung cells are capable of spontaneously organizing themselves into small, multi-cellular structures that possess motility. These anthrobots They behave and organize differently. Not only can they move around their environment, but they are also capable of repairing themselves as well as damaged neurons nearby.

These discoveries collectively highlight the flexible nature of cellular systems and contradict the notion that evolution in cells and organisms occurs solely through predefined pathways. The concept of the third state implies that the demise of an organism might be crucial in shaping the transformation of life across different periods.

Postmortem conditions

Several factors influence Whether particular cells and tissues remain viable and functional following an organism’s death. Factors such as environmental conditions, metabolic activity, and preservation methods play key roles here.

Diverse cell types exhibit different lifespans. For instance, in humans, white blood cells expire between 60 and 86 hours post organ failure. In mice, skeletal muscle cells can regenerate after 14 days following death, whereas fibroblast cells from sheep and goats can be cultured up to a month or so postmortem.

Metabolic activity is crucial for the ongoing survival and functionality of cells. Active cells Those requiring an ongoing and significant amount of energy to sustain their functions prove harder to cultivate compared to cells needing less energy. Preservation methods for these can be challenging as well. such as cryopreservation Can enable tissue samples like bone marrow to operate akin to living donor sources.

Inherent survival mechanisms Additionally, they play a crucial part in determining if cells and tissues survive. For instance, scientists have noted a substantial rise in the activity level of genes linked to stress and genes associated with immunity following an organism's demise, potentially aimed at offsetting the reduction in homeostasis Furthermore, elements like trauma , infection , and the time elapsed since death considerably impact the health and survival of tissues and cells.

Elements like age, health, gender, and kind of organism also influence the postmortem environment. This becomes apparent in the difficulty associated with cultivating and transferring tissues. metabolically active islet cells , which produces insulin in the pancreas, from donors to recipients. Researchers think that autoimmune responses, high energy demands, and the deterioration of protective mechanisms might be responsible for numerous failures in islet transplants.

The way these factors interact to enable specific cells to keep operating following an organism’s death is not well understood. A proposed theory suggests that particular channels and transporters within the cell's external membranes might play a crucial role. intricate electrical circuits These channels and pumps create electrical impulses that enable cells to interact with one another and carry out particular tasks like proliferation and migration, thus contributing to the architecture of the organism they compose.

The degree to which various cell types can transform following death remains unclear. Prior studies have identified certain genes associated with stress, immunity, and more. epigenetic regulation are activated following death mice, zebrafish , and people , indicating broad possibilities for change across various cell types.

Consequences for biology and medical science

Not only does the third state provide fresh perspectives on cell adaptability, but it also opens up possibilities for developing novel therapies.

For example, anthrobots could be sourced From a person's living tissue, medications can be delivered without causing an undesirable immune reaction. Engineered nanobots introduced into the body might break down arterial plaques in individuals with atherosclerosis and eliminate extra mucus in those suffering from cystic fibrosis.

Significantly, these multicellular organisms possess a limited lifespan, deteriorating over time as expected. four to six weeks This " kill switch" stops the development of possibly invasive cells.

Enhanced comprehension of how certain cells persist in functioning and transform into multicellular structures even after an organism has died could hold potential for advancing personalized and preventative medical practices.

The article was initially posted on The Conversation by Peter A Noble from the University of Washington and Alex Pozhitkov from the Irell & Manella Graduate School of Biological Sciences at City of Hope. Read the original article here .