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. 2022 Mar 31;11(7):1174. doi: 10.3390/cells11071174

Figure 8.

Figure 8

(a) Effects of co-administration of growth differentiation factor-6 (GDF-6) and atelocollagen (AC) on tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 expression compared with AC alone in a rat tail puncture model. After establishment of the intervertebral disc (IVD) degeneration model, vehicle (phosphate-buffered saline [PBS]; 2 μL per disc, group P), AC (2-μL AC per disc, group AC), or GDF-6 (20 μg in 2-μL AC gel per disc, group G + AC) was randomly injected. Pro-inflammatory cytokines were assessed using immunofluorescence (TNF-α: green, IL-6: red, CD24: purple, 4′,6-diamidino-2-phenylindole [DAPI]: blue, and merged signals) of the IVDs at 14 and 28 days after injection in high-power fields (×400). Immunopositivity was calculated as a percentage relative to DAPI-positive cells. We designated the control without puncture (groups C and C′), and compared the four groups (C, P, A, G + AC) and (C′, P′, G′, G + AC′). Data are expressed as the mean ± standard deviation (n = 6). One-way analysis of variance (ANOVA) with the Tukey–Kramer post-hoc test was used. Significant differences are set as * p < 0.050 and ** p < 0.010. (b) Effect of co-administration of GDF-6 and AC on TNF-α and IL-6 expression compared with GDF-6 alone in a rat tail puncture model. After establishment of the IVD degeneration model, vehicle (PBS; 2 μL per disc, group P′), GDF-6 (20 μg in 2-μL PBS per disc, group G′), or GDF-6 (20 μg in 2-μL AC gel per disc, group G + AC′) was randomly injected. Pro-inflammatory cytokines were assessed using immunofluorescence (TNF-α: green, IL-6: red, CD24: purple, DAPI: blue, and merged signals) of the IVDs at 14 and 28 days after injection in high-power fields (×400). Immunopositivity was calculated as a percentage relative to DAPI-positive cells. We designated the control without puncture (groups C and C′), and compared the four groups (C, P, A, G + AC) and (C′, P′, G′, G + AC′). Data are the mean ± standard deviation (n = 6). One-way ANOVA with the Tukey–Kramer post-hoc test was used. Significant differences are set as * p < 0.050 and ** p < 0.010.