Effects of hyperbaric oxygen at 1.25 atmospheres absolute with normal air on macrophage number and infiltration during rat skeletal muscle regeneration

• Published in: PloS one Vol. 9; no. 12; p. e115685
• Main Authors: Fujita, Naoto, Ono, Miharu, Tomioka, Tomoka, Deie, Masataka
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 22.12.2014; Public Library of Science (PLoS)
• Subjects: Animals; Atmosphere; Atmospheres; Biology and Life Sciences; Biotechnology; Blotting, Western; Bupivacaine; Cell Differentiation - drug effects; Cells, Cultured; Exposure; Gene expression; Health sciences; Hyperbaric oxygen; Hyperbaric Oxygenation - methods; Hypoxia; Infiltration; Injection; Injury prevention; Interleukin; Interleukin 10; Interleukin-10 - genetics; Interleukin-10 - metabolism; Laboratory animals; Macrophages; Macrophages - cytology; Macrophages - drug effects; Macrophages - metabolism; Male; Medicine and Health Sciences; Metastases; Muscle Development; Muscle, Skeletal - cytology; Muscle, Skeletal - drug effects; Muscle, Skeletal - injuries; Muscle, Skeletal - metabolism; Muscles; Musculoskeletal system; MyoD protein; Myogenin; Myogenin - genetics; Myogenin - metabolism; Nuclei; Oxygen; Oxygen - pharmacology; Oxygen therapy; Proteins; Rats; Rats, Wistar; Real-Time Polymerase Chain Reaction; Recovery of Function - drug effects; Recovery of Function - physiology; Regeneration; Regeneration - drug effects; Regeneration - physiology; Research and Analysis Methods; Respiratory therapy; Reverse Transcriptase Polymerase Chain Reaction; RNA; RNA, Messenger - genetics; Rodents; Skeletal muscle; Studies; Tibialis anterior muscle; Tumor necrosis factor-α; Wound Healing - drug effects
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0115685

Use of mild hyperbaric oxygen less than 2 atmospheres absolute (2026.54 hPa) with normal air is emerging as a common complementary treatment for severe muscle injury. Although hyperbaric oxygen at over 2 atmospheres absolute with 100% O2 promotes healing of skeletal muscle injury, it is not clear whether mild hyperbaric oxygen is equally effective. The purpose of the present study was to investigate the impact of hyperbaric oxygen at 1.25 atmospheres absolute (1266.59 hPa) with normal air on muscle regeneration. The tibialis anterior muscle of male Wistar rats was injured by injection of bupivacaine hydrochloride, and rats were randomly assigned to a hyperbaric oxygen experimental group or to a non-hyperbaric oxygen control group. Immediately after the injection, rats were exposed to hyperbaric oxygen, and the treatment was continued for 28 days. The cross-sectional area of centrally nucleated muscle fibers was significantly larger in rats exposed to hyperbaric oxygen than in controls 5 and 7 days after injury. The number of CD68- or CD68- and CD206-positive cells was significantly higher in rats exposed to hyperbaric oxygen than in controls 24 h after injury. Additionally, tumor necrosis factor-α and interleukin-10 mRNA expression levels were significantly higher in rats exposed to hyperbaric oxygen than in controls 24 h after injury. The number of Pax7- and MyoD- or MyoD- and myogenin-positive nuclei per mm2 and the expression levels of these proteins were significantly higher in rats exposed to hyperbaric oxygen than in controls 5 days after injury. These results suggest that mild hyperbaric oxygen promotes skeletal muscle regeneration in the early phase after injury, possibly due to reduced hypoxic conditions leading to accelerated macrophage infiltration and phenotype transition. In conclusion, mild hyperbaric oxygen less than 2 atmospheres absolute with normal air is an appropriate support therapy for severe muscle injuries.