Platelet microparticle; a potential targeted drug delivery system
Platelet microparticle; a potential targeted drug delivery system
Alireza KhanAhmad,1,*
1. Department of Hematology and Medical Laboratory Sciences, Faculty of Allied Medicine, Kerman University of Medical Sciences, Kerman, Iran
Introduction: Along with undeniable advantages, systemic administration of chemical drugs may accompany severe toxicity and side effects due to adverse reactions with normal cells. The ideal situation for disease treatment is to transport drugs directly to the target organs, tissues, cells, and even specific organelles. Although several drug delivery systems such as liposomes and different synthetic nanoparticles have been identified, their clinical application is crippled by high costs and limited biological adaptability. Therefore, the development of new systems seems to be crucial.
Platelets are anucleated cells with the main activity in the coagulation system. Activation of platelets in physiological or pathological circumstances leads to the formation of platelet microparticles (PMPs).
PMPs, extracellular fragments secreted by activated platelets, range in size from 0.1 to 1 μm in diameter. PMPs account for more than 70% of circulating microparticles. PMPs are safe, inexpensive, and biocompatible particles that have the capacity to carry drugs. The presence of platelet membrane antigens on PMPs covers them against the phagocytic system and prolongs their half-life in comparison with other microparticles. Besides, autologous PMPs may be applicable to prevent adverse transfusion reactions.
The present study aims to overview the application of PMPs as a specified drug delivery system in a variety of diseases.
Methods: A literature search was done in Web of Science, PubMed, and Scopus using related keywords such as platelet microparticles, platelet extra-cellular vesicles, platelet-derived microparticles, platelet-derived extracellular microvesicles, drug delivery system, target therapy, etc. No time, language, or article type restriction was performed. An additional manual search of the references of related articles was also conducted.
Results: To date, isolating PMPs and loading drugs are known as the major complications of using PMPs as a drug delivery system. Although some studies suggest incubation instead of sonication and freeze-thaw for loading drugs in PMPs, lacking a single standard protocol results in variable outcomes.
In recent years, there have been great advances in loading different therapeutic agents on PMPs. For instance, promising effects for loading antivirals such as Lamivudine and Tenofovir disoproxil fumarate have been documented using different cell lines. In addition, anti-tumor agents were also tested. For example, Kailashiya et al. (2019) reported that Doxorubicin (DOX) loaded PMPs showed much greater toxicity compared with the equivalent dose of free DOX. They also revealed that incubation of cancer cells with PMP-DOX for an hour resulted in 7 times higher drug uptake than those incubated with DOX alone.
Conclusion: Previous studies prepared preliminary insights into drug-loaded PMPs and suggested that drug-loaded PMPs may be clinically applicable in the near future. However, the Mechanisms by which PMPs transport drugs to different cells are yet to be fully understood. In addition, further in-vitro and in-vivo studies are needed to realize the effects of drug-loaded PMPs in other diseases. Possible adverse effects including procoagulant activities of PMPs are also still unclear.