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Extracellular vesicles (EVs) are lipid bilayer-delimited particles that are naturally released from almost all types of cells but, unlike a cell, cannot replicate. EVs range in diameter from near the size of the smallest physically possible unilamellar liposome (around 20-30 nanometers) to as large as 10 microns or more, although the vast majority of EVs are smaller than 200 nm.
For example, tumor cells can accumulate drugs into microvesicles. Subsequently, the drug-containing microvesicles are released from the cell into the extracellular environment, thereby mediating resistance to chemotherapeutic agents and resulting in significantly increased tumor growth, survival, and metastasis. [20] [34]
Exosome-mediated delivery of superoxide dismutase extends life-span in Caenorhabditis elegans, apparently by reducing the level of reactive oxygen species. [89] Thus this system is being studied for its anti-aging potential. [89] This delivery system also improved survival under conditions of oxidative stress and heat. [89]
However, due to exosomes being small in size (30-150 nm), present in various biological fluids (such as blood, urine, saliva), sensitivity to environmental factors (such temperature, pH), complexity of drug loading efficiency, there are challenges associated with isolation, purification, delivery and drug payload.
6 Extracellular vesicles. 7 See also. 8 References. ... Thus, it is very difficult to target abnormal cells by the conventional method of the drug delivery system ...
Vesicles can also fuse with other organelles within the cell. A vesicle released from the cell is known as an extracellular vesicle. Vesicles perform a variety of functions. Because it is separated from the cytosol, the inside of the vesicle can be made to be different from the cytosolic environment. For this reason, vesicles are a basic tool ...
Polymersomes have been used to create controlled release drug delivery systems. [9] Similar to coating liposomes with polyethylene glycol, polymersomes can be made invisible to the immune system if the hydrophilic block consists of polyethylene glycol. [10] Thus, polymersomes are useful carriers for targeted medication.
Transient vesicle fusion is driven by SNARE proteins, resulting in release of vesicle contents into the extracellular space (or in case of neurons in the synaptic cleft). The merging of the donor and the acceptor membranes accomplishes three tasks: The surface of the plasma membrane increases (by the surface of the fused vesicle).