Abstract: Disclosed is a method for detecting chemotaxis of neutrophil, including: mixing a blood sample and an equal volume of glucose, mixing, and standing; taking a supernatant of the blood sample after standing into a centrifuge tube, and centrifuging; adding 1× calcium and magnesium ion-free HBSS into a centrifuged blood sample to re-suspend cell aggregates at bottom; uniformly blowing and dispersing a re-suspended bottom cell aggregates, and slowly adding a polysucrose solution from the bottom of the centrifuge tube to perform density gradient centrifuging treatment; dividing a density gradient centrifuged solution into three layers, pipetting a clear liquid at an upper layer and a PBMC layer at a middle layer to obtain cell aggregates at a bottom layer; lysing erythrocytes in the cell aggregates, then successively adding 2× calcium and magnesium ion-free HBSS and 1× calcium and magnesium ion-free HBSS, mixing, and centrifuging again to obtain neutrophils.

Abstract: The present disclosure relates to the field of miRNA and exosomes, in particular to the use of miRNA in preparation of drugs for preventing and treating osteoarthritis, and the use of miRNA exosomes with high expression. The present disclosure provides the use of miR-155-5p in preparation of drugs for preventing and/or treating osteoarthritis. The nucleotide sequence of miR-155-5p is set forth in SEQ ID NO.:1. Use of the present disclosure can improve miR-155-5p expression by targeting miR-155-5p to Runx2, promote chondrocyte growth proliferation, migration, and extracellular matrix secretion and inhibition of cell apoptosis, thus producing the effect of preventing or treating osteoarthritis.