The homing of human cord blood stem cells to sites of inflammation: unfolding mysteries of a novel therapeutic paradigm for glioblastoma multiforme.

Efficient homing of human umbilical cord blood mesenchymal stem cells (hUCBSC) to inflammation sites is crucial for therapeutic use. In glioblastoma multiforme, soluble factors released by the tumor facilitate the migratory capacity of mesenchymal stem cells toward glioma cells. These factors include chemokines and growth inducers. Nonetheless, the mechanistic details of these factors involved in hUCBSC homing have not been clearly delineated. The present study is aimed to deduce specific factors involved in hUCBSC homing by utilizing a glioma stem cell-induced inflammatory lesion model in the mouse brain. Our results show that hUCBSC do not form tumors in athymic nude mice brains and do not elicit immune responses in immunocompetent SKH1 mice. Further, hUCBSC spheroids migrate and invade glioma spheroids, while no effect was observed on rat fetal brain aggregates. Several cytokines, including GRO, MCP-1, IL-8, IL-3, IL-10, Osteopontin and TGF-β2, were constitutively secreted in the naive hUCBSC-conditioned medium, while significant increases of IL-8, GRO, GRO-α, MCP-1 and MCP-2 were observed in glioma stem cell-challenged hUCBSC culture filtrates. Furthermore, hUCBSC showed a stronger migration capacity toward glioma stem cells in vitro and exhibited enhanced migration to glioma stem cells in an intracranial human malignant glioma xenograft model. Our results indicate that multiple cytokines are involved in recruitment of hUCBSC toward glioma stem cells, and that hUCBSC are a potential candidate for glioma therapy.