Figure 8: Maturation of SOX2-induced new neurons in the injured adult spinal cord.

(a) Experimental scheme. mGfap-Cre;Rosa-tdT mice were injected with hGFAP-SOX2 or a control virus immediately after injury and analysed by IHC at 4 (I) or 8 (II, III) wpi. (b,c) Expression of the mature neuronal markers MAP2 (b) or NeuN (c) in tdT⁺ cells in SOX2 virus-injected spinal cords at 8 wpi. tdT-traced MAP2⁺ or NeuN⁺ cells were not detectable in control virus-injected spinal cords. Orthogonal views of cells with expression of the indicated markers are also shown. Compared with endogenous spinal motoneurons (indicated by an asterisk in c), the SOX2-induced neurons are interneuron-like with a smaller soma (indicated by an arrow in c). (d,e) SOX2-induced mature neurons pass through a proliferative stage. Mice were treated with BrdU at 3–18 dpi and analysed at 8 wpi. Orthogonal views of BrdU-traced mature neurons are also shown. (f,g) Quantification of SOX2-induced mature neurons in the injured adult spinal cord (mean+s.d.; n=5 mice per group; *P<0.01 by Student’s t-test). Scale bar, 20 μm (b–e).