Umbilical cord blood can be a rich source of stem/progenitor cells, not only for hematopoetic but also for other tissue-specific lineages. Recently, we have developed a novel, self-renewed neural-like stem cell line named HUCB-NSC from human cord blood. To test if HUCB-NSCs can supply brain in need of regeneration, we injected these cells into immunosuppressed intact rat forebrain and to animals suffering from a photothrombotic cortical lesion at 48 h after injury. The survival, migration, and differentiation of the transplanted HUCB-NSCs were measured at 7 and 30 days post-transplantation by immunohistochemical methods. Results show survival and extensive migration of transplanted neural-like progenitors into damaged brain cortex during the first week of post-stroke recovery. The donor cells accumulated mainly in peri-infarct area and then differentiated showing a strong co-expression of neuronal (NF-200) but only moderate of astrocytic (GFAP) cell markers. However, the paucity of HUCB-NSCs detected within post-ischemic rat brain at the end of a 1 month period, as well as acute rejection of grafted cells by intact, yet cyclosporin A (CsA) immunosuppressed, rat brain tissue, suggests development of a severe adverse host reaction to the presence of alien donor cells and an urgent need for further study of the immunological response evoked by xenotransplantations of human cord blood-derived cells in animal experimental models.