Introduction: The promising of neuron progenitor cells (NPCs) or endothelial progenitor cells (EPCs) for treating ischemic stroke has been recognized. In this study, we determined the therapeutic effects of NPC and EPC co-transplantation and the underlying mechanisms in a mouse model of ischemia-reperfusion (I-R) stroke.
Methods: NPCs and EPCs were generated from human inducible pluripotent stem cells. C57BL/6 adult mice were subjected to middle cerebral artery occlusion (MCAO; 90 min) followed by reperfusion (30 min), and treated with (n=10/group): 1) PBS; 2) EPCs; 3) NPCs; 4) EPCs+NPCs (1:1 ratio); 5) EPCs+NPCs (1:1 ratio)+LY294002 (1μM). Cells (3x105/2μl PBS) were injected into ipsilateral striatum at 2 sites (1μl/site). Bromodeoxyuridine (BrdU, 65 mg/g/day, i.p.) was injected to label the new generated cells. Mice were sacrificed at days 2 and 10. Motor function (Rotarod test and neurologic deficit score), infarct volume, cerebral microvascular density (cMVD), neurogenesis and angiogenesis, and gene expressions of the PI3K/Akt pathway were evaluated.
Results: Co-transplantation of EPCs and NPCs exhibited synergistic effects on improving motor function, increasing cMVD in the peri-infarct area, and decreasing infarct volume at days 2 and 10 (refer to table). Moreover, neurogenesis (Brdu+NeuN+) and angiogenesis (Brdu+CD31+) in the peri-infarct area were largely enhanced in the co-transplantation group at day 10 (refer to table). In addition, the protein ratio of p-Akt/Akt was increased in the brain in the co-transplantation group (p<0.05). These effects were significantly reduced by LY294002 administration.
Conclusion: Co-transplantation of NPCs and EPCs synergistically increases cMVD, promotes angiogenesis and neurogenesis, and improves functional outcome in I-R injured mice. Activation of the PI3K/Akt signal pathway contributes to the synergistic effects of NPCs and EPCs.