title: Exosomes: novel effectors of human platelet lysate activity.
abstract: Despite the popularity of platelet-rich plasma (PRP) and platelet lysate (PL) in orthopaedic practice, the mechanism of action and the effectiveness of these therapeutic tools are still controversial. So far, the activity of PRP and PL has been associated with different growth factors (GF) released during platelet degranulation. This study, for the first time, identifies exosomes, nanosized vesicles released in the extracellular compartment by a number of elements, including platelets, as one of the effectors of PL activity. Exosomes were isolated from human PL by differential ultracentrifugation, and analysed by electron microscopy and Western blotting. Bone marrow stromal cells (MSC) treated with three different exosome concentrations (0.6 μg, 5 μg and 50 μg) showed a significant, dose-dependent increase in cell proliferation and migration compared to the control. In addition, osteogenic differentiation assays demonstrated that exosome concentration differently affected the ability of MSC to deposit mineralised matrix. Finally, the analysis of exosome protein content revealed a higher amount of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF-BB) and transforming growth factor beta 1 (TGF-β1) as compared to PL. In regards to RNA content, an enrichment of small RNAs in exosomes as compared to donor platelets has been found. These results suggest that exosomes consistently contribute to PL activity and could represent an advantageous nanodelivery system for cell-free regeneration therapies.
authors.affiliation: Istituto Ortopedico Rizzoli, Laboratory for Orthopaedic Pathophysiology and Regenerative Medicine, via di Barbiano 1/10, 40136 Bologna, Italy.elena.torreggiani@ior.it.
authors.forename: E
authors.initials: E
authors.lastname: Torreggiani
authors.forename: F
authors.initials: F
authors.lastname: Perut
authors.forename: L
authors.initials: L
authors.lastname: Roncuzzi
authors.forename: N
authors.initials: N
authors.lastname: Zini
authors.forename: S R
authors.initials: SR
authors.lastname: Baglìo
authors.forename: N
authors.initials: N
authors.lastname: Baldini
mesh_terms: D000077214:Becaplermin; D001792:Blood Platelets / Q000737:chemistry*; D002454:Cell Differentiation; D002457:Cell Extracts / Q000737:chemistry* / Q000494:pharmacology; D049109:Cell Proliferation; D055354:Exosomes / Q000737:chemistry* / Q000648:ultrastructure; D016222:Fibroblast Growth Factor 2 / Q000032:analysis / Q000494:pharmacology; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D035683:MicroRNAs / Q000032:analysis; D020574:Proto-Oncogene Proteins c-sis / Q000032:analysis / Q000494:pharmacology; D053773:Transforming Growth Factor beta1 / Q000032:analysis / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis / Q000494:pharmacology
chemical_list: D002457:Cell Extracts; D035683:MicroRNAs; D020574:Proto-Oncogene Proteins c-sis; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D000077214:Becaplermin