The Effect of Silver Nanoparticles on the Healing Process of Excisional Skin Wounds in Adult Albino Rats: Histological and Immunohistochemical Study

Abstract

Abstract Background The ultimate goal for wound healing is a speedy recovery with minimal scarring. Different approaches have been used for achieving this goal such as antimicrobials and cell growth promoting agents. Recently, silver nanoparticles (AgNps) have become of interest in biomedical applications, because of their antibacterial, antifungal, antiviral and anti-inflammatory activity. Aim was to investigate the role of AgNps on the healing process of excisional skin wounds in adult male albino rats. Material & Methods 72 male albino rats weighing 200 g were obtained from research center, Ain Shams Faculty of Medicine and subjected to excisional skin wounds 1.5 cm in diameter on their mid-backs. Then rats were divided into 4 groups 18 rats each; control (group I) skin wounds were left to heal naturally. Other wounds were topically treated once daily with methylcellulose hydrogel (group II), silver sulphadiazine (group III), and AgNps in methylcellulose hydrogel (group IV). For each group 6 rats were sacrificed on each of the following days post-wounding; 3rd, 7th and 14th. Skin specimens from all groups were fixed in 10% neutral formalin & processed for paraffin sections which were stained with Hx & E, Mallory’s Trichrome and vascular endothelial growth factor (VEGF). Using image analysis software, number of (macrophages, newly formed blood vessels & fibroblasts) and area % of collagen fibers deposition were assessed and statistically analyzed. Results Control and methylcellulose hydrogel groups revealed almost similar results. Re-epithelialization started on day 3 post-wounding only in AgNps treated group and on day 7 in all other groups. Epithelialization was complete on day 14 only in AgNps treated group and the dermis was mostly regenerated with the appearance of skin appendages. Components of the granulation tissue varied considerably among the studied groups and across the three time points. In Hx & E stained sections the number of macrophages was highest in AgNps treated group on day 3 post-wounding then was the lowest on days 7 and 14 compared with other groups as confirmed by image analysis. Neovascularization started on day 3 in all groups but was prominent on AgNps treated group which showed high density on day 7 as proved statistically and by results of VEGF immune staining. The number of the newly formed blood vessels declined on day 14 in AgNps treated group and remained high in silver sulphadiazine group and showed maximum density in control groups. Statistical analysis proved that the number of fibroblasts in AgNps group was maximum on day 7 & decreased to minimum on day 14 compared with all other groups. In Mallory’s trichrome stained sections the area percent of collagen fibers deposition in the granulation tissue was maximum in AgNps treated group across all periods of the study compared to other studied groups. Conclusion AgNps showed advantage of rapid healing of excisional skin wounds in rats compared with traditional methods of treatment. It might be the treatment of choice particularly for high risk patients.