Neuronal apoptosis in host brain. (A, B, F) TUNEL staining shows that neuronal apoptosis increased significantly after TBI (P <0.01 versus sham group), (B, C, D, E, F) whereas separate or combined transplantation of NSCs and OECs has a reverse effect on neuronal apoptosis (P <0.05 versus TBI; P <0.01 versus TBI), and (C, D, E, F) results with co-grafting are the best (P <0.05 versus NSC; P <0.05 versus OEC). Bars = 100 μm, shown in (A). *Statistical significance of P <0.05. #Statistical significance of P <0.01. NSC, neural stem cell; OEC, olfactory en sheathing cell; TBI, traumatic brain injury; TUNEL, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling.