Fig. 2: Hyper-IL-6 promotes CST axon regeneration after severe spinal cord crush. | Nature Communications

Fig. 2: Hyper-IL-6 promotes CST axon regeneration after severe spinal cord crush.

From: Transneuronal delivery of hyper-interleukin-6 enables functional recovery after severe spinal cord injury in mice

Fig. 2

a Timeline of surgical interventions for experiments presented in (b–i) and Figs. 3, 4. PTENf/f mice received unilateral injections of AAV2-GFP (PTEN+/+) or AAV2-Cre (PTEN−/−) at P1. After 7 weeks, PTEN+/+ and PTEN−/− mice were then subjected to spinal cord crush (SCC) (T8) and subsequently received additional unilateral intracortical injections of either AAV2-hIL-6 (hIL-6) or AAV2-GFP (gfp). b Sagittal thoracic spinal cord sections of four differently treated groups showing BDA-labeled, retracting axons (white) of the right main CST rostral to the lesion site (dotted line). Tissues were isolated 8 weeks after the SCC. Scale bar: 500 µm. c Axon density index of CST fibers analyzing all spinal cord sections with the main CST of the animals described in (a, b). Values at distances from 1.5 mm rostral to the lesion site (−1.5) up to the proximal lesion border (0) were determined. Values represent means ± SEM of 6–10 animals per group (PTEN+/+/gfp, n = 7; PTEN+/+/hIL-6, n = 9; PTEN−/−/gfp, n = 6; PTEN−/−/hIL-6, n = 10). d Representative images of BDA-labeled sagittal spinal cord sections from PTEN-floxed mice (PTENf/f) after treatments, as described in (a, b). Tissues were isolated after 8 weeks. BDA-labeled (white) regenerating axons of the central CST beyond the lesion site (dotted line) were seen only after PTEN−/−, hIL-6, or hIL-6/PTEN−/−-treatments. Scale bar: 500 µm. e–h Higher magnification of regenerating axons in dotted boxes as indicated in (d). Scale bar: 500 µm. i Quantification of regenerating CST axons at the indicated distances caudal to the lesion site. Axon numbers were divided by the total number of BDA-labeled CST fibers in the medulla (axon index) from animals as described in (a, d). Values represent the mean ± SEM of 6–10 animals per group (PTEN+/+/gfp, n = 7; PTEN+/+/hIL-6, n = 9; PTEN−/−/gfp, n = 6; PTEN−/−/hIL-6, n = 10). Significances of intergroup differences in (c, i) were evaluated using a three-way analysis of variance (ANOVA) with Holm Sidak post hoc tests. Statistical significance is indicated by p-values; ns = non-significant. Dots in c and i represent values of single animals. Source data are provided as a Source data file.

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