Host cells and tissues via secreted paracrine factors and extracellular vesicles

This entry describes a complex physiological mechanism of intercellular communication rather than a single molecular target. It encompasses the paracrine effect, where cells release soluble signaling molecules—such as cytokines, chemokines, and growth factors—and membrane-bound extracellular vesicles (EVs), including exosomes and microvesicles, to influence the behavior of neighboring or distant host cells (Journal of Clinical Investigation, 2019). These secreted components carry a diverse cargo of bioactive molecules that modulate critical biological processes such as inflammation, tissue regeneration, and immune evasion. In the context of modern drug development, this system is frequently leveraged in 'cell-free' regenerative medicine, where the secretome or purified EVs from stem cells are used as therapeutic agents to treat conditions like myocardial infarction and respiratory distress (Advanced Drug Delivery Reviews, 2020). Conversely, in oncology, blocking the paracrine factors or EVs released by tumor cells is a strategy to inhibit the formation of the pre-metastatic niche. Because this term refers to a broad biological pathway involving hundreds of distinct molecular entities and transport vehicles, it is classified as a mechanism of action or a delivery environment rather than a discrete therapeutic target.

Other names

Paracrine signalingCell secretomeExtracellular vesicle-mediated communicationExosome-mediated signalingIntercellular communication

Paracrine signaling involves the secretion of soluble ligands that bind to receptors on adjacent cells, while extracellular vesicles (EVs) transfer proteins, lipids, and functional RNAs (miRNA, mRNA) to recipient cells via endocytosis or membrane fusion (Nature Reviews Molecular Cell Biology, 2018).