Mouse-targeted amino acid sequencing, transmission electron microscopy for in vitro observation, immunofluorescence for both in vivo and in vitro analyses, and siRNA transfection in vitro were employed in this study.<h4>Results</h4>Our results showed that MSCs significantly improved the skin lesion of mice with psoriasis, and reduced the levels of inflammatory factors and chemokines including IL-1β, IL-6, IL-8, TNF-α, MCP-1, CCL7, CCL20 and CCL27 in the mouse skin lesion areas and M5- induced psoriatic KCs models in vitro. This evidence concerns the gene CCL20 and psoriasis.