Comparison and Investigation of Exosomes Derived from Platelet-Rich Plasma Activated by Different Agonists

PRP-Exos are nanoscale cup-shaped vesicles that carry a variety of proteins, mRNAs, microRNAs, and other bioactive substances. PRP-Exos can be formed through several induction pathways, which determine their molecular profiles and facilitate their tailormade participation in intercellular communication. Currently, little is known on how the PRP-Exos activation method influences the quality and quantity of PRP-Exos. The present study aims to observe and analyze the number, profile, and growth factors of PRP-Exos through TEM, Nanoflow, and WB after PRP activation and compare the difference in function of PRP-Exos on HUVECs, with different stimuli (calcium gluconate, thrombin, or both). We found that PRP activated with both thrombin and calcium gluconate harvested the highest concentration of exosomes [(7.16 +/- 0.46) x 10(10) particles/ml], compared to thrombin group [(4.87 +/- 0.15) x 10(10) particles/ml], calcium gluconate group [(5.85 +/- 0.43) x 10(10) particles/ml], or saline group [(7.52 +/- 0.19) x 10(9) particles/ml], respectively (P < 0.05) via Nanoflow analysis. The WB analysis showed that cytokines (VEGF, PDGFBB, bFGF, TGF-<beta>) are differentially encapsulated in PRP-Exos, depending on the PRP stimulus, in which the mixture-PRP-Exos yielded the highest concentration of cytokines. In the function assay of PRP-Exos on HUVECs, the mixture-PRP-Exos promoted HUVECs proliferation, increased HUVECs migration, promoted the formation of vessel-like by HUVECs via the AKT ERK signal pathway more dramatically, compared with other groups. In summary, our studies showed that PRP activated by the mixture of calcium gluconate and thrombin harvested the best quality of exosomes which had the top biological functions. This study provides a protocol for selecting appropriate PRP activators to obtain high-quality exosomes for future applications.