Taken together, for improvement of AD, cASCs and cASC-EVs regulated histamine or IgE release by prohibiting infiltration of mast cells, and skin barrier dysfunction induced by IL-4 and IL-13 by blocking infiltration of T cells, and pruritus skin stimulated by the phosphorylation of STAT1, and 3 through the increment of IL-31/IL-31R expression in T cell by IL-4. The gene discussed is IL31; the disease is Alzheimer disease.