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Figure 2. Exosome-based cancer therapies. Currently, four different methods have been developed for cancer therapies: (1) natural
exosomes from some immune cells to suppress cancer cells; (2) inhibition of cancer cells-derived exosomes; (3) exosomes as gene
carriers; and (4) exosomes as anti-cancer drug carriers (This figure was created with BioRender.com)

cell-cell communication from cancer-cell derived exosomes appears to offer an exciting new way to treat
cancer.

Exosomes as gene carriers for cancer therapy
Although, there is great potential for exosomes in cancer therapy, the use of natural exosomes is hard and
rarely achieves the expected therapeutic result. Fortunately, engineered exosomes carrying specific proteins,
RNAs, or drugs have been found to possess great potential for effective cancer treatment.

Exosomes as miRNA carrier for cancer therapy
miRNAs are endogenous, small, non-coding RNAs that can regulate gene expression by binding to target
mRNAs. Therefore, miRNAs could be a powerful tool for cancer therapy. However, miRNAs are easily
degraded in vivo and delivery of miRNAs to their specific target cells/tissue/organ is a major challenge.
As exosomes are stable small vesicles that can carry functional bioactive molecules long distances with a
[2-6]
high degree of target specificity , they have been suggested as a potential carrier for miRNAs in cancer
therapy. Over the last few years, many scientists have focused on exosomal-based delivery of miRNAs and
[83]
miRNA inhibitors for cancer therapy [83-88] . For instance, in 2013, Katakowski et al. reported that exosomes
enriched with the anti-glioma miRNA (miRNA-146b) can suppress glioma growth in vitro and can also
significantly reduce glioma xenograft growth in rats. Similarly, miR-101-enriched exosomes can suppress
[85]
[84]
osteosarcoma cell invasion/migration in vitro and suppress metastasis in vivo . Wang et al. also reported
that exosomes loaded with miR‐335‐5p can decrease cancer growth and invasion both in vitro and in vivo.