bFGF and collagen matrix hydrogel attenuates burn wound inflammation through activation of ERK and TRK pathway

Abstract

Burn injuries are most challenging to manage since it causes loss of the integrity of large portions of the skin leading to major disability or even death. Over the years, hydrogels are considered as a significant delivery system for wound treatment because of several advantages over other conventional formulations. We hypothesized that the bFGF-collagen-AgSD incorporated hydrogel formulation can accelerate the rate of burn healing in animal model and would promote fibroblast cell proliferation. Neovascularization and re-epithelialization is a hall mark of burn wound healing. In the present study, histopathological investigation and scanning electron microscopy of skin tissue of Wistar rats showed almost complete epithelialisation after 16 days in the treatment group. The developed hydrogel showed significantly accelerated wound closure compared with a standard and control group. The faster wound closure resulted from increased re-epithelialization and granulation tissue formation because of the presence of collagen and growth factor. Expressions of proteins such as TrkA, p- TrkA, ERK1/2, p-ERK1/2, NF-kβ, and p-NF-kβ involved in nerve growth factor (NGF) signalling pathway were analysed by western blot. All the findings obtained from this study indicated that the hydrogel can be considered as a promising delivery system against second degree burn by faster healing.

Figure 1

(A) Pictorial representation of rat skin after burn injury. (B) Comparative efficacy of different formulations on partial thickness burn wound healing in Wistar rats. (C) Hydroxyproline content of different treated groups.

Figure 2

(A) Histopathology of different treated groups; (a) normal skin of rat, (b) untreated burned skin, (c) Rat skin of standard group on 8th day and (d) on 16th day, (e) BOF treated skin on 8th day and (f) on 16th day by using HE stain. (B) Histopathology of different treated groups; a) normal skin of rat, (b) untreated burned skin, (c) Rat skin of standard group on 16th day, (d) BOF treated skin on 8th day and (e) on 16th day by using MT stain. (C) Scanning electron microscopy of skin tissue of Wistar rats; (A) normal skin of rat, (B) untreated burned skin, (C) standard group, (D) BOF treated.

Figure 3

(A) Estimation of pro- and anti-inflammatory cytokines (A) IL-1β, (B) IL-6, (C) Rat TNF and (D) IL-10 after burn wound on 4th, 8th, 12th and 16th day by using rat serum. Data are expressed as mean ± SEM (n = 3). *** indicates p˂0.001, ** indicates p˂0.01, * indicates p˂0.05 as compared to the control group and ### indicates p˂0.001, ## indicates p˂0.01, # indicates p˂0.05 as compared to the standard group. (B) Western blotting analysis of β actin, Trk A, p-Trk A, ERK1/2, p-ERK1/2 NF-kβ, p-NF-kβ expressions in burn skin tissue of rats from different treatment groups. Data are expressed as mean ± SEM (n = 3). *** indicates p˂0.001, ** indicates p˂0.01, * indicates p˂0.05 as compared to the negative control group.

Figure 4

(A) Bio-distribution study of AgSD in partial thickness burn wounds of Wistar rats. (B) The cytotoxicity effect of hydrogel formulation on L929 cell line. Untreated cells were considered as negative control and 1% DMSO as vehicle control (***p˂0.0001). (C) Representative photographs of L929 cells maintained in culture medium. (D) Treatment of L929 cells with hydrogel formulation increases cell proliferation as detected by BrdU cell proliferation assay.