Exosomes are very small extracellular vesicles secreted by multiple cell types and are extensively distributed in various biological fluids. Recent research indicated that exosomes can participate in regulating the tumor microenvironment and impacting tumor proliferation and progression. Due to the extensive enrollment in cancer development, exosomes have become a focus of the search for a new therapeutic method for cancer. Exosomes can be utilized for the therapeutic delivery of small molecules, proteins and RNAs to target cancer cells with a high efficiency. Exosome-carried proteins, lipids and nucleic acids are being tested as promising biomarkers for cancer diagnosis and prognosis, even as potential treatment targets for cancer. Moreover, different sources of exosomes exhibit multiple performances in cancer applications. In this review, we elaborate on the specific mechanism by which exosomes affect the communication between tumors and the microenvironment and state the therapeutic and diagnostic applications of exosomes in cancers.
Epicatechin gallate (ECG) is a main effective catechin widely existing in natural plants and food, with well-known health benefits. The present study first designed a new exosome-based delivery system for ECG and examined its neuroprotective effects on a rotenone (Rot)-induced Parkinson's disease (PD) model in vitro. Exosomes (Exo) were isolated from fresh bovine milk, and their average size was 85.15 ± 2.00 nm. ECG was encapsulated into Exo by a sonication method, and the loading efficiency of ECG-loaded exosomes (ECG-Exo) was 25.96 ± 0.45%. The neuroprotective effects of ECG-Exo were evaluated on Rot-induced SHSY5Y cells and compared with free ECG. Cell viability, cellular reactive oxygen species, apoptosis rate, and the expressions of caspase-3, Bax, Bcl-2, parkin, PINK1, and Atg5 were determined. Our results showed that Exo delivered ECG successfully into SHSY5Y cells and exhibited enhanced neuroprotective effects. ECG-Exo might inhibit SHSY5Y cell damage induced by Rot through antiapoptosis and antimitophagy.
Parkinson’s
disease (PD) is the second most common neurodegenerative
disease around the world. Current treatments alleviate the symptoms
through the administration of drugs, including dopamine precursors,
dopamine metabolism inhibitors, and activated dopamine agonists, but
they cannot prevent the ongoing dopaminergic damage. One of the pivotal
factors is the poor drug transport efficiency of crossing the blood–brain
barrier, while studies reveal that exosomes are endogenous vesicles
that are useful for drug delivery and disease diagnosis. As drug carriers,
exosomes can not only deliver effective therapeutic drugs but also
conquer difficulties such as biocompatibility, blood–brain
barrier penetrability, metabolic stability, and target specificity.
Exosomes have been successfully loaded with catalase, dopamine, catalase
mRNA, and small interfering RNA for PD treatment and shown significant
therapeutic effects. As diagnostic indicators (biomarkers), exosomes
are more sensitive and reliable. They can reflect the pathological
conditions and monitor disease progression. Exosomes from cerebrospinal
fluid, plasma, serum, saliva, and urine are valuable biomarkers for
PD diagnosis. This review mainly illuminates the association between
exosomes and PD, sums up the therapeutic and diagnostic applications
of exosomes in PD, and raises some critical remaining questions on
the field. It is proposed that future investigations could be dedicated
to exploiting a standard procedure to prepare large-scale exosomal
carriers with high loading efficiency and new components of exosomes
as biomarkers (mRNA; receptors), for better therapeutic and diagnostic
options of PD.
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