**Author details**

applied [93]. Interestingly, it has been reported that melanoma cells treated with the anticancer drug cisplatin eliminated the cisplatin through EVs [94]. When human pancreatic adenocar‐ cinoma CFPAC-1 cells were treated with EVs containing paclitaxel, this produced an anti-

Another promising therapeutic application of EVs is through the delivery of molecules to certain organs or cells using a phenomenon known as EV tropism. There have been various attempts to use this pathway for treatment of brain disorders and cancer. For example, Alvarez-Erviti et al. [7] used EVs as part of a neuronal-specific delivery system to effect an siRNAmediated knockdown of the β-site amyloid precursor protein cleaving enzyme 1 (BACE1), an initiating enzyme required for β-amyloid peptide synthesis. A significant reduction (60%) of the BAAlzCE1, at both mRNA and protein level, was achieved in the brain cortical tissue by this delivery system, indicating its utility for the treatment of Alzheimer's disease. Zhao et al. [96] showed that systemic administration of glial cell line-derived neurotrophic factor to a Parkinson's disease (PD) mouse model, significantly ameloriated both neurodegradation and neuroinflammation through the specific transmission of the neurotrophic factor by the released EVs into the target neurons. Also Zhuang et al. [97] showed that intranasal delivery of EVs containing curcumin or the STAT3 inhibitor JS1-124 to microglial cells in mice signifi‐ cantly reduced Lipopolysaccharide (LPS)-induced brain inflammation and delayed tumour growth in the GL26 tumour model. Furthermore, Pascucci et al. [95] showed a strong antiproliferative activity of EVs delivered from mesenchymal stromal cells (MSCs) incorporated with paclitaxel, against the human pancreatic CFPAC-1 cell-line. These data suggest a more potent and specific cell target delivery system aiming to increase the anti-tumour efficiency of chemotherapeutic drugs. Skog et al. [22] demonstrated a future possibility to use EVs as a diagnostic tool for certain tumours, such as glioblastoma. These tumour cells are able to release their own EVs, which contain mRNA/miRNA and proteins into the blood stream. Various mRNA/miRNA characteristics of glioblastoma cells were detected in the blood in about onethird of the tested glioblastoma patients, suggesting its utility in diagnosis and for design of

EVs are endogenous carriers that facilitate intercellular communication. Although their existence has been known for a long time, they have attracted recent renewed interest because of their possible participation in the spread of particularly cancer initiating or metastasis promoting agents from tumour cells, which appear to produce them in excessive amounts. By the same token, EVs from normal cells may be able to reverse the malignant characteristics of cancer cells by transfer of tumour suppressors or pro-apoptotic molecules, providing more 'natural' therapy. In the drug delivery field, they are causing much excitement as potential therapeutics because of their efficient transfer of proteins, mRNA and miRNA, as well as existing drugs, into selective targets. They have obvious advantages over artificial liposomes

tumour effect [95].

98 Tumor Metastasis

*5.1.2. Organ tropism of EVs*

optimal treatment plans for each patient.

**6. Future perspectives**

Monerah Al Soraj1 , Salma Bargal2 and Yunus A. Luqmani2\*

\*Address all correspondence to: yluqmani@yahoo.com

1 Department of Pharmaceutics, Faculty of Pharmacy, Kuwait University, Safat, Kuwait

2 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Kuwait University, Safat, Kuwait
