Delayed Intranasal Delivery of Hypoxic-Preconditioned Bone Marrow Mesenchymal Stem Cells Enhanced Cell Homing and Therapeutic Benefits After Ischemic Stroke in Mice

Stem cell transplantation therapy has emerged as a potential treatment for ischemic stroke and other neuro-degenerative diseases. Effective delivery of exogenous cells and homing of these cells to the lesion region, however, have been challenging issues that hinder the efficacy and efficiency of cell-based therapy. In the present investigation, we tested a delayed treatment of noninvasive and brain-targeted intranasal delivery of bone marrow mesenchymal stem cells (BMSCs) in a mouse focal cerebral ischemia model. The investigation tested the feasibility and effectiveness of intranasal delivery of BMSCs to the ischemic cortex. Hypoxia preconditioning (HP) of BMSCs was performed before transplantation in order to promote their survival, migration, and homing to the ischemic brain region after intranasal transplantation. Hoechst dye-labeled normoxic- or hypoxic-pretreated BMSCs (1 x 10(6) cells/animal) were delivered intranasally 24 h after stroke. Cells reached the ischemic cortex and deposited outside of vasculatures as early as 1.5 h after administration. HP-treated BMSCs (HP-BMSCs) showed a higher level of expression of proteins associated with migration, including CXC chemokine receptor type 4 (CXCR4), matrix metalloproteinase 2 (MMP-2), and MMP-9. HP-BMSCs exhibited enhanced migratory capacities in vitro and dramatically enhanced homing efficiency to the infarct cortex when compared with normoxic cultured BMSCs (N-BMSCs). Three days after transplantation and 4 days after stroke, both N-BMSCs and HP-BMSCs decreased cell death in the peri-infarct region; significant neuroprotection of reduced infarct volume was seen in mice that received HP-BMSCs. In adhesive removal test of sensorimotor functional assay performed 3 days after transplantation, HP-BMSC-treated mice performed significantly better than N-BMSC- and vehicle-treated animals. These data suggest that delayed intranasal administration of stem cells is feasible in the treatment of stroke and hypoxic preconditioning of transplanted cells, significantly enhances cell's homing to the ischemic region, and optimizes the therapeutic efficacy.