Figure 6.

PRV transsynaptic tracing labels neurons in the graft. Ten weeks after cell transplantation, PRV-614 was injected into the bilateral kidneys to transsynaptically trace reestablished supraspinal sympathetic pathways in RN-NSC-grafted rats (n = 8). A, B, At 72 h after inoculation (n = 4), immunolabeling shows that (A) numerous PRV-infected SPNs emerge in the IML of caudal spinal cord, which are (B) colabeled by FG (arrowheads). Some viral-infected neurons, but not FG-labeled (arrows), are observed in the middle area of gray matter, indicating the possibility of interneuronal identity linked to the SPNs. C–E, PRV injection transfects RN-NSCs in the grafts after 72 (C) or 96 h (D, E) (n = 4) proliferation and transportation times. C, Inset, A PRV-labeled neuron (arrowhead) in the graft with high magnification. F–H, Importantly, 5-HT antibody costaining verifies that a portion of PRV-infected neurons in the graft are serotonergic. I, Statistical analysis shows that the number of PRV-infected neurons in the graft is not significantly (NS) (unpaired t test, p > 0.05) different from 72 to 96 h after injection. This suggests that grafted RN-NSCs rebuild descending autonomic regulation pathways following SCI by forming synaptic connectivity with spinal SPNs. Scale bars: A, 1.7 mm; B, 75 μm; D, 80 μm; E, H, 20 μm.