# MALDI-TOF/MS Analysis of Extracellular Vesicles Released by Cancer Cells
## 3 Conclusions  
The extracellular vesicles released by cells have long been considered a way to discard unwanted products, by functioning as cellular waste disposers. Currently, they are recognized as key factors in intercellular crosstalk in both healthy and pathological tissues including cancer, a condition in which EVs are released in greater quantities and are involved in several processes, including angiogenesis, proliferation, metastasis, immune evasion, and drug resistance. The central functions performed by EVs in the progression of cancer make them a natural study target for inferring crucial information on different aspects of tumors. Over the years, MALDI-TOF mass spectrometry has been increasingly employed for the characterization of EVs and their internal cargo released by different types of cancer cells, demonstrating its potential in a wide range of applications. Most of the publications, summarized in Table 1, have been devoted to proteomic studies on topics such as the identification of new biomarkers for early diagnosis, metastasis, follow-up, drug resistance prediction, tumor differentiation, epithelial-to-mesenchymal transition, and many others. Of course, a full characterization of EVs is not possible using a single analytical technique, since they carry the components of different classes associated with different biological functions and diseases. In fact, some reported applications have been performed using combined LC-MS and MALDI approaches in an attempt to obtain a more complete picture of the system under investigation.  
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**Authors** & **Cancer Type** & **Objective** & **Main Findings** & **Ref** \\ \hline [PERSON] et al. & Mesothelioma & Proteomic analysis of exosomes & Identification of several proteins & [20] \\ \hline [PERSON] et al. & Breast & Proteomic analysis of exosome-like vesicles & 179 proteins identified, 32 isoforms & \\  & & & & \\  & & & & \\ \end{tabular}
\end{table}
Table 1: Objectives and main findings of the MALDI-TOF applications for the analysis of tumor derived EVs.  
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Certainly, the application of these mass spectrometry techniques to such complex bioanalytical problems presents some contraindications, especially with regard to the potential extension of strategies from basic science to patient care. Particularly, more effective, and less expensive isolation protocols for EVs should be developed, that can integrate with the analytical instrumentation in an automated way and be standardized. Furthermore, the task is made more complicated by inherent problems, such as the complexity of the biological matrices from which EVs must be extracted and the changeable and heterogeneous composition of the content of EVs with a large number of variables. On the other hand, even though EVs have often been analyzed using LC-MS, likely because chromatographic separation helps to reduce the complexity of these matrices, MALDI-TOF surely represents a more appropriate instrument for extending the methods to clinical practice due to its intrinsic advantages in terms of high-throughput, rapidity, cost-effectiveness, and ease of use. In fact, it is important to point out that more than half the articles reviewed in this work have been published in the last five years, evidence that represents a clear sign of how the MALDI-TOF approach is becoming increasingly central in the context of studying exosomes.  
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**Funding:** This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** The author thanks [PERSON] for her statistical support.  
**Conflicts of Interest:** The author declares no conflict of interest.