Did dye

Tetracycline (TET), berberine (BB), kanamycin, ampicillin, doxycycline, oxyTetracycline, gentamicin, chloramphenicol, lincomycin, baicalin, capsicine, betaine, cannabidiol, glycine, gluutamine, tyrosine, ascorbic, Dulbecco's PBS (DPBS), thioflavin T (ThT), acetonitrile, trichloromethane, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and cholesterol were purchased from Sigma-Aldrich (St. Louis, MO). All chemical reagents were analytical grade and were used as received without further purification. The ultrapure water (UP) used throughout all experiments was purified by a Milli-Q system (Millipore, Bedford, MA, USA). The raw liquid milk was purchased from the local pasture. 4% (w/v) paraformaldehyde, Hoechst 33342 and DiD dye were purchased from Beyotime Biotechnology (Shanghai, China).
High-performance liquid chromatography purified oligonucleotides (ODNs) were purchased from Shanghai Sangon Biological Engineering Technology & Services (Shanghai, China), and used without additional purification (See Supplementary Table S1 for details of DNA sequences used). Each sequence was diluted in UP into 100 μmol l⁻¹. For better formation of secondary conformation, sequences were heated to 95 °C for 5 min and colded to room temperature overnight, and was stored at −20 °C before use.

To observe the internalization of MSC-Exo into neutrophils, exosomes were labeled with DiD dye (Beyotime, C1995S) according to the manufacturer’s instructions and washed with PBS followed by centrifugation at 50,000g for 1 h at 4 °C. Then, the DiD-labeled MSC-Exo were co-cultured with primary neutrophils at a final concentration of 20 μg/mL. After 6 hours, the cells were washed with PBS and stained with DAPI. Finally, the cells were examined and photographed with a conventional fluorescence microscope (Leica Thunder, Germany). ImageJ software was used to measure uptake as whole image fluorescence intensity for neutrophils.