title: Microcurrent electrical neuromuscular stimulation facilitates regeneration of injured skeletal muscle in mice.
abstract: Conservative therapies, mainly resting care for the damaged muscle, are generally used as a treatment for skeletal muscle injuries (such as muscle fragmentation). Several past studies reported that microcurrent electrical neuromuscular stimulation (MENS) facilitates a repair of injured soft tissues and shortens the recovery period. However, the effects of MENS on the regeneration in injured skeletal muscle are still unclear. The purpose of this study was to investigate the effect of MENS on the regenerative process of injured skeletal muscle and to elucidate whether satellite cells in injured skeletal muscle are activated by MENS by using animal models. Male C57BL/6J mice, aged 7 weeks old, were used (n = 30). Mice were randomly divided into two groups: (1) cardiotoxin (CTX)-injected (CX, n = 15) and (2) CTX-injected with MENS treatment (MX, n=15) groups. CTX was injected into tibialis anterior muscle (TA) of mice in CX and MX groups to initiate the necrosis-regeneration cycle of the muscle. TA was dissected 1, 2, and 3 weeks after the injection. Muscle weight, muscle protein content, the mean cross-sectional areas of muscle fibers, the relative percentage of fibers having central nuclei, and the number of muscle satellite cells were evaluated. MENS facilitated the recovery of the muscle dry weight and protein content relative to body weight, and the mean cross-sectional areas of muscle fibers in CTX-induced injured TA muscle. The number of Pax7-positive muscle satellite cells was increased by MENS during the regenerating period. Decrease in the percentages of fibers with central nuclei after CTX-injection was facilitated by MENS. MENS may facilitate the regeneration of injured skeletal muscles by activating the regenerative potential of skeletal muscles. Key pointsMicrocurrent electrical neuromuscular stimulation (MENS) facilitated the recovery of the relative muscle dry weight, the relative muscle protein content, and the mean cross-sectional areas of muscle fibers of injured TA muscle in mice.The number of satellite cells was increased by MENS during the regenerating phase of injured skeletal muscle.Decrease in the percentages of fibers with central nuclei was facilitated by MENS.MENS may facilitate the regeneration of injured skeletal muscles.
authors.affiliation: Department of Sports Medicine, St. Marianna University School of Medicine , Kawasaki, Kanagawa, Japan ; St.Marianna University School of Medicine, FIFA Medical Centre of Excellence at Kawasaki , Kawasaki, Kanagawa, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Fujiya
authors.affiliation: Department of Physiology, St. Marianna University School of Medicine , Kawasaki, Kanagawa, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ogura
authors.affiliation: Laboratory of Physiology, School of Health Sciences, Toyohashi SOZO University , Toyohashi, Aichi, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Ohno
authors.affiliation: Department of Physiology, Graduate School of Health Sciences, Toyohashi SOZO University , Toyohashi, Aichi, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Goto
authors.affiliation: Department of Physiology, Graduate School of Health Sciences, Toyohashi SOZO University , Toyohashi, Aichi, Japan.
authors.forename: Ayane
authors.initials: A
authors.lastname: Nakamura
authors.affiliation: Department of Physiology, Graduate School of Health Sciences, Toyohashi SOZO University , Toyohashi, Aichi, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ohashi
authors.affiliation: Laboratory of Physiology, School of Health Sciences, Toyohashi SOZO University , Toyohashi, Aichi, Japan.
authors.forename: Daiki
authors.initials: D
authors.lastname: Uematsu
authors.affiliation: St.Marianna University School of Medicine, FIFA Medical Centre of Excellence at Kawasaki , Kawasaki, Kanagawa, Japan.
authors.forename: Haruhito
authors.initials: H
authors.lastname: Aoki
authors.affiliation: Department of Sports Medicine, St. Marianna University School of Medicine , Kawasaki, Kanagawa, Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Musha
authors.affiliation: Laboratory of Physiology, School of Health Sciences, Toyohashi SOZO University , Toyohashi, Aichi, Japan ; Department of Physiology, Graduate School of Health Sciences, Toyohashi SOZO University , Toyohashi, Aichi, Japan.
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Goto
keywords: Muscle injury; central nuclei; muscle satellite cell; physiotherapy; regenerative potential; sports injury