The Association of Rose Bengal with Macrophage Polarization and Oxidative Stress Response in Full-Thickness Excisional and Grafted Burn Wounds: A Porcine In Vivo Study.

Background and

Objectives

Burn wounds are associated with delayed healing, infection, and pathological scarring. Effective repair requires tightly regulated immune and oxidative stress responses, including macrophage polarization. This study evaluated the association of the photosensitizer Rose Bengal, delivered in a hydrogel vehicle, with macrophage polarization and oxidative stress after burn injury. Materials and

Methods

Three female red Duroc pigs underwent full-thickness contact burns followed by excision and autografting. Wounds received 20% Pluronic F-127 hydrogel containing 0.1% Rose Bengal sodium, hydrogel alone, or PBS (phosphate-buffered saline) on days 1, 7, and 14 post-burn. Biopsies from days 7 and 120 were analyzed by immunohistochemistry for pan-macrophage marker, CD206 (M2 macrophages), CD3E (T-cell infiltration), and 4-hydroxynonenal (4-HNE; oxidative stress marker). Mean fluorescence intensity was analyzed using two-way ANOVA with Tukey's post hoc test (mean ± SD, p < 0.05).

Results

At day 120, Rose Bengal treatment showed higher pan-macrophage expression (0.80 ± 0.07) compared with PBS (0.62 ± 0.10; p = 0.0034), whereas the difference versus hydrogel (0.68 ± 0.07; p = 0.0628) was not significant. CD206 expression was similarly higher in Rose Bengal-treated wounds (0.77 ± 0.06) compared with PBS (0.62 ± 0.05; p = 0.0277); hydrogel also differed from PBS (p = 0.0287), without a difference between hydrogel and Rose Bengal. For CD3E, a significant main effect of treatment was observed (F(2,12) = 8.346, p = 0.0054), with lower values in Rose Bengal versus PBS at day 120 (p = 0.0360). No differences in 4-HNE were detected.

Conclusions

Rose Bengal-hydrogel treatment was associated with increased macrophage presence and enhanced M2 polarization without increased T-cell infiltration. Effects were significant versus PBS but not hydrogel, suggesting Rose Bengal may contribute to a pro-regenerative immune microenvironment without excessive adaptive activation.