(A: SEM images of the lyophilized NGF-HP hydrogel. B: The efficiency of FITC cellular uptake in vitro. C: Cells viability of various groups in vitro. PC12 cells were induced by H2O2 before the treatments. *P<0.05, **P<0.01 vs. H2O2 group. D: Quantitative analysis the neurite length of H2O2 induced-PC12 cells after different treatments in vitro. E: BBB locomotion assessments of SCI rats at different time points in different groups. The score of control group was 21 points, means normal locomotion SCI group. HP hydrogel, NGF solution and NGF-HP hydrogel were injected in situ (OI). F: The inclined plane test scores of SCI rats in control group, SCI group, HP hydrogel (OI) group, NGF (OI) group and NGF-HP hydrogel (OI) group at different time points. All data are presented as Mean ± SD, n = 5; *P < 0.05 and **P < 0.01, determined by two-tailed student’s t-test.)