Background: Exosomes are membrane vesicles which cells secrete into the extracellular space. They are involved in many physiological processes, like immune response and tissue regeneration, as well as pathological processes, e.g. inflammation and cancer. They are also involved in intercellular communication, as they carry many signaling molecules, such as proteins, lipids and nucleic acids (DNA, mRNA, microRNA). Due to their load, which reflects the composition of the originating cell, they are an important source of various diagnostic markers. More and more clinical research is conducted in the therapeutic use of exosomes, which have many advantages especially compared to stem cells from which they originate.
Methods: Systematic review of literature has been performed using the following online bibliographic databases: Clinicaltrials.gov, Cochrane library and MEDLINE. We have selected those clinical research studies in which human exosomes or altered human exosomes were used for therapeutic or diagnostic purposes. In the latter case, we limited ourselves to prostate and lung cancers. Due to a large number of ongoing studies, we performed the analysis of their global trends. Selected parameters, such as number of participating subjects, types of exosomes used, etc., were presented graphically. The selected properties of all studies were presented in tables.
Results: Following stringent inclusion/ exclusion criteria, 53 studies were selected for analysis. Thirty of them were dealing with therapeutic and 23 with diagnostic use of human exosomes. In the first group the most commonly used exosomes in clinics were derived from mesenchymal stem cells, and were mostly investigated in treatment of respiratory diseases, neoplasms, and neurological and skin diseases. Most clinical trials were open-label, non-randomised, and phase I. Therefore, the average length of a clinical trial in this group is 1,9 years. Most of the analysed diagnostic studies were cohort studies. There were also many validating diagnostic tests based on exosomal markers. In terms of new diagnostic markers, microRNAs were those being mainly investigated. On average, this type of research takes 3 years.
Conclusion: The field of exosomes is rather new, and holds a great potential for their therapeutic and diagnostic use.
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