This invention relates to stem cell microparticles and miRNA isolated from these microparticles, their use and production thereof, in particular neural stem cell microparticles and their use in therapy of cancer, typically a nestin-positive cancer. The cancer may be glioma, melanoma, breast cancer, pancreatic cancer or prostate cancer. The stem cell microparticle is typically an exosome or microvesicle and may be derived from a neural stem cell line. The neural stem cell line may be a conditionally-immortalised stem cell line such as CTX0E03 (deposited at the ECACC with Accession No. 04091601).