Starlight Longevity

Intercellular Communication and Ageing

Why It Matters

Ageing is not only a matter of damage inside individual cells. It also reflects changes in how cells, tissues, and organs signal to one another through inflammatory mediators, hormones, metabolites, and vesicle-bound cargo. For that reason, altered intercellular communication is treated as a core hallmark of ageing in the hallmark framework. [1]

Systemic Signals Can Shift Tissue Function

Experiments in heterochronic parabiosis, where young and old mice share a circulatory system, showed that age-related decline is partly shaped by blood-borne signals rather than only by irreversible local damage. Exposure to a younger systemic environment improved regeneration in aged muscle and liver, while exposure to an older systemic milieu impaired neurogenesis and cognition in younger animals. These findings support the idea that ageing has an important non-cell-autonomous component. [2] [3]

Follow-up work in aged mice also found that young plasma could improve some measures of hippocampal plasticity and learning. Even so, these studies remain preclinical and do not imply that any single circulating factor explains ageing broadly. [4] [1]

Extracellular Vesicles as Mobile Cargo

Extracellular vesicles are membrane-bound particles released by many cell types into tissues and body fluids. They can carry proteins, lipids, and nucleic acids, allowing cells to influence nearby or distant targets. Reviews of ageing biology describe them as plausible mediators of long-range communication because they circulate in blood and their cargo reflects the state of the cells that produced them. [5] [1]

Human and mouse studies suggest that extracellular vesicle profiles change with age. Reported changes include shifts in concentration, uptake by immune cells, and microRNA cargo, which is consistent with the broader idea that ageing changes the quality of intercellular signals as well as their quantity. [6] [7]

Senescent Cells Can Spread Signals Beyond Their Point of Origin

Senescent cells are one major source of altered communication in ageing tissues. In addition to soluble SASP factors, they release extracellular vesicles that can modify recipient cells and reinforce senescence-related phenotypes. Experimental work has shown that small extracellular vesicles from senescent cells can contribute to paracrine senescence, meaning that one stressed cell population can propagate dysfunction into surrounding tissue. [8] [7]

This matters because ageing phenotypes often appear at tissue and organism scale. If senescent or otherwise stressed cells alter circulating vesicle cargo, inflammatory tone, or endocrine balance, the downstream effects may accumulate across multiple organs rather than remaining localized. [1] [5] [7]

What Remains Uncertain

The concept is well supported, but the specific mediators are still being mapped. In many cases, studies identify age-associated factors without proving that they are universal drivers of human ageing. Extracellular vesicle biology is also technically difficult: isolation methods differ, vesicle subclasses overlap, and results from mouse models do not automatically generalize to people. [5] [6] [7]

Related Reading

Summary

Intercellular communication is central to ageing because tissues do not age in isolation. Evidence from systemic-exposure experiments, circulating-factor studies, and extracellular vesicle research suggests that age-related decline is shaped partly by signals moving between cells and organs, although the most important mediators in humans remain an active area of research. [1] [2] [5]

Educational Disclaimer

This content is provided for educational purposes only and does not constitute medical advice.

References

  1. Lopez-Otin, C. et al. "Hallmarks of aging: An expanding universe." Cell (2023). https://pmc.ncbi.nlm.nih.gov/articles/PMC10809922/
  2. Conboy, I. M. et al. "Rejuvenation of aged progenitor cells by exposure to a young systemic environment." Nature (2005). https://pubmed.ncbi.nlm.nih.gov/15716955/
  3. Villeda, S. A. et al. "The ageing systemic milieu negatively regulates neurogenesis and cognitive function." Nature (2011). https://pubmed.ncbi.nlm.nih.gov/21886162/
  4. Villeda, S. A. et al. "Young blood reverses age-related impairments in cognitive function and synaptic plasticity in mice." Nature Medicine (2014). https://pubmed.ncbi.nlm.nih.gov/24793238/
  5. Robbins, P. D., Morelli, A. E. "Extracellular vesicles and aging." Aging Medicine (2018). https://pmc.ncbi.nlm.nih.gov/articles/PMC5762993/
  6. Eitan, E. et al. "Age-Related Changes in Plasma Extracellular Vesicle Characteristics and Internalization by Leukocytes." Scientific Reports (2017). https://pmc.ncbi.nlm.nih.gov/articles/PMC5430958/
  7. Alibhai, F. J. et al. "Cellular senescence contributes to age-dependent changes in circulating extracellular vesicle cargo and function." Aging Cell (2020). https://pubmed.ncbi.nlm.nih.gov/31960578/
  8. Borghesan, M. et al. "Small Extracellular Vesicles Are Key Regulators of Non-cell Autonomous Intercellular Communication in Senescence via the Interferon Protein IFITM3." Cell Reports (2019). https://pmc.ncbi.nlm.nih.gov/articles/PMC6613042/