Intradermal methylene blue administration on the progression of burn injuries

Research performed at:

1. Department of Surgery, Ribeirao Preto School of Medicine, University of Sao Paulo, Ribeirao Preto, Sao Paulo, Brazil.

2. Department of Social Medicine, Ribeirão Preto School of Medicine, University of São Paulo, Brazil.

The authors:

Vinícius FM Beldi, Marina J Rosique, Luis Fernando Tirapelli, Eny KU Moriguti, Altacílio A Nunes, Jayme A Farina Jr, Paulo Roberto B Evora.

A burn injury has two defined areas: central necrosis and an adjacent area of ischaemia, which may or may not progress to necrosis. The concentration of nitric oxide (NO) increases after burn injury and may originate from potent oxidising agents. Methylene blue (MB) may act as an antioxidant and is supposed to reduce burn progression. This investigation was carried out to evaluate the effects of intradermal MB on necrosis progression in burns.

Full-thickness burn injuries were performed by applying a heated metal comb on the shaved back of male Wistar rats. The animals were divided into three groups: Control (C, n=7); MB (2mg/kg) one hour after burn injury (MB1h, n=11); and MB (2mg/kg) six hours after burn injury (MB6h, n=8). After seven days the lesions were photographed for visual assessment of burn necrosis; full-thickness cuts of lesions were dyed with Masson and Giemsa for microscopic histopathology; and tissue fragments of unburned interspaces were processed for chemiluminescence with nitrite/nitrate (NOX) and malondialdehyde (MDA) as oxidative stress markers.

The study provided good evidence that MB intradermal injection can reduce necrosis progression in ischaemic perilesional areas and suggests an alternative to treating burns.