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Keywords:

  • lentivirus;
  • megakaryocyte;
  • microparticle;
  • platelet;
  • PPARγ;
  • thrombopoiesis

Sahler J, Woeller C, Spinelli S, Blumberg N, Phipps R. A novel method for overexpression of peroxisome proliferator-activated receptor-γ in megakaryocyte and platelet microparticles achieves transcellular signaling. J Thromb Haemost 2012; 10: 2563–72.

Summary.  Background: Microparticles are submicrometer vesicles that contain RNA and protein derived from their parent cells. Platelet and megakaryocyte microparticles represent 80% of circulating microparticles, and their numbers are elevated in diseases such as cancer and type 2 diabetes. The ability of microparticles to transport protein, lipid and RNA to target cells, as a means of transcellular communication, remains poorly understood. Determining the influence that microparticles have on circulating cells is essential for understanding their role in health and in disease. Objectives: To develop a novel approach to modify the composition of platelet microparticles, and understand how such changes impact their transcellular communication. Methods: This novel model utilizes a lentiviral technology to alter the transcription factor peroxisome proliferator-activated receptor-γ (PPARγ) content of megakaryoblastic cell lines and primary megakaryocytes, and also the protein composition of generated platelets and microparticles. The subsequent microparticles were isolated and added to target cells for assessment of uptake and resultant signaling events. Results: We successfully engineered microparticles to contain green fluorescent protein and elevated levels of PPARγ. We found that these altered microparticles could be internalized by the monocytic cell line THP-1 and primary human microvascular endothelial cells. Importantly, microparticle-delivered PPARγ was shown to increase the expression of fatty acid-binding protein 4 (FABP4), which is a known PPARγ target gene in THP-1 cells. Conclusion: This proof-of-concept modification of megakaryocyte, platelet and microparticle composition and subsequent change in target cell physiology is an important new tool to address transcellular communication of microparticles.