The present invention relates to mesoblast-derived stem cell-derived microparticles having proliferation promoting activity of corneal epithelial stem cells and / or corneal epithelial cells, undifferentiated maintaining activity of corneal epithelial stem cells or colony forming promoting activity, or corneal epithelium protecting action.本発明は、角膜上皮幹細胞及び/又は角膜上皮細胞の増殖促進活性、角膜上皮幹細胞の未分化維持活性又はコロニー形成促進活性、或いは角膜上皮保護作用を有する、間葉系幹細胞由来微粒子に関する。