Exosome-modified PLGA Microspheres for Improved Internalization into Dendritic Cells and Macrophages

Considering the significance of effective antigen presentation for boosting immune responses, it is essential to develop delivery systems for antigen presenting cells (APCs; dendritic cells and macrophages). As a simple and facile way for improving delivery efficiency of PLGA microspheres (MS) into APCs, we fabricated exosome-conjugated PLGA MS via polydopamine coating in this study. Spherical micro-sized particles were first prepared by conventional water-in oil-in water (W-1/O/W-2) double emulsion and solvent evaporation methods and were observed by scanning electron microscopy (SEM). With increasing model protein (ovalbumin)/MS weight ratios, higher amounts of ovalbumin (OVA) were immobilized onto MS. After exosome (EXO) conjugation to MS via polydopamine coating, the amount of nitrogen was significantly increased on the surface of MS, indicating that EXO were successfully conjugated onto MS. EXO-coated dopamine MS (EXO-Dopa MS) exhibited significantly improved delivery into DC2.4 cells and RAW264.7 cells, compared with bare MS and Dopa MS. Therefore, EXO-Dopa MS could be used as effective carriers of immune stimulating biomolecules into APCs for cancer immunotherapy.