In subgroup IIa1 (Sacrifice 1week following muscle injury) the injured area demonstrated atypical fibers widely separated by infiltrating cells and distended capillaries. In accordance,some authors stated that thermal injury of gastrocnemius muscle of rat revealed greater interfiber distances and substantially increased amount of connective tissue 1. Other investigators added that within the first week of traumatic muscle injury, granulated tissue and acute inflammation were found 9.
Most fibers contained dark nuclei, indicating apoptosis. The fibers revealed partial loss of striations, and some fibers recruited strong acidophilic sarcoplasm with focal vacuolations on close observation. Some authors related injury of DNA to reactive oxygen species 18. In addition, some investigators described similar degenerative cytoplasmic changes after muscle injury 2.
In subgroup IIa2 (sacrificed 3 weeks after muscle injury), atypical fibers appeared separated by a few infiltrating cells. Some fibers exhibited dark nuclei and partial loss of striations. The previous results indicated mild regression of degenerative changes. Concomitantly, some workers documented that mononuclear cells can develop into a variety of different muscle cell lineages, including myoblasts, Scs, and muscle-derived stem cells 19.
In subgroup IIb1 (sacrificed 1 week after injury and MCT), a few atypical fibers were found. Other fibers exhibited multiple flat nuclei, some of which were centrally located. Striations appeared in some areas of the sarcoplasm. Some authors postulated that MCT limits muscle damage and inflammation, known as delayed-onset muscle soreness in cases of injury 12. Other investigators reported improved neuromuscular conductivity in response to MCT following muscle injury 20. Some workers recorded that Scs are the adult skeletal muscle stem cells that are quiescent, but during muscle regeneration proliferate and generate distinct daughter cells by segregating template DNA strands to the stem cell 21.
In subgroup IIb2 (Sacrifice 3 weeks following injury and MCT), few atypical fibers were seen surrounded by multiple typical fibers, some of which were observed with centrally located nuclei. Multiple fibers recruited striations in most areas of the sarcoplasm. These findings indicated progressive improvement of structural changes by MCT, proved by a significant decrease in mean area of atypical fibers. Some authors mentioned that Scs are located beneath the basal lamina of adult muscle fibers and are normally arrested in G0 of the cell cycle 22. They can be activated in response to stimuli, initiating a regenerative process, restoring the normal architecture of muscle within 2 weeks. This was confirmed by some workers who stated that survival of the satellite cells is a critical requirement for efficient muscle reconstitution following injury 23.
The regenerative capacity was assessed in the present work using α-SMA. In subgroup IIa2 a few positive spindle cells were detected among some fibers with partial loss of striations. In subgroup IIb1 positive spindle cells were more evident, and in subgroup IIb2 positive cells multiplied among the muscle fibers. This was confirmed by a significant increase in the mean area% of α-SMA-positive cells. Some authors postulated that activation of muscle precursor cells is an important determinant for the efficiency of muscle regeneration. It was added that the main source of muscle precursor cells are Scs, which proliferate and migrate to the injured site 24.
In subgroup IIa1, occasional CD34+ve spindle and oval cells appeared around atypical fibers. Subgroup IIa2 demonstrated few +ve spindle cells among muscle fibers. On the other hand, in subgroup IIb1 multiple +ve spindle cells were obvious at the periphery of muscle fibers. While in subgroup IIb2 the +ve spindle cells appeared less. This was evidenced by a significant increase in the mean area% of CD34 +ve cells in mirourrent group. Some investigators documented Scs within adult skeletal muscle as an enriched population of CD34+ve cells 16. Some authors proved that Scs are responsible for the regenerative potential of skeletal muscle 25. Some investigators considered that CD34 beyond being a stem cell marker, may play an important function in modulating stem cell activity 26. On the other hand, workers noted a minority of satellite cells lacking CD34 has been described 6.
There is no conflict of interest to declare.
1. Oliveira F, Bevilacqua LR, Anaruma CA, Boldrini Sde C, Liberti EA.Morphological changes in distant muscle fibers following thermal injury in Wistar rats.Acta Cir Bras2010;25:525–528.
2. Gumerson JD, Michele DE.The dystrophin–glycoprotein complex in the prevention of muscle damage.J Biomed Biotechnol20111–13.
3. Kim MY, Kwon DR, Lee HI.Therapeutic effect of microcurrent
therapy in infants with congenital muscular torticollis.PM R2009;1:736–739.
4. Lee BY, Al-Waili N, Stubbs D, Wendell K, Butler G, Al-Waili T, Al-Waili A.Ultra-low microcurrent
in the management of diabetes mellitus, hypertension and chronic wounds: report of twelve cases and discussion of mechanism of action.Int J Med Sci2009;7:29–35.
5. Aliyev RM, Geiger G.Cell-stimulation therapy of lateral epicondylitis with frequency-modulated low-intensity electric current.Bull Exp Biol Med2012;152:653–655.
6. Ieronimakis N, Balasundaram G, Rainey S, Srirangam K, Yablonka-Reuveni Z, Reyes M.Absence of CD34 on murine skeletal muscle satellite cells
marks a reversible state of activation during acute injury.PLoS One2010;5:e10920–e10935.
7. Armand AS, Laziz I, Djeghloul D, Lécolle S, Bertrand AT, Biondi O, et al..Apoptosis-inducing factor regulates skeletal muscle
. Progenitor cell number and muscle phenotype.PLoS One2011;6:e27283–e27307.
8. Riuzzi F, Sorci G, Beccafico S, Donato R.S100B engages RAGE or bFGF/FGFR1 in myoblasts depending on its own concentration and myoblast density. Implications for muscle regeneration.PLoS One2012;7:e28700–e28717.
9. Lee YS, Kwon ST, Kim JO, Choi ES.Experimental study in a rat model with the pathologic correlation.Korean J Radiol2011;12:66–77.
10. Passarini JR Jr, Gaspi FO, Neves LM, Esquisatto MA, Santos GM, Mendonça FA.Application of Jatropha curcas
L. seed oil (Euphorbiaceae) and microcurrent
on the healing of experimental wounds in Wistar rats.Acta Cir Bras2012;27:441–447.
11. Mehmandoust FG, Torkaman G, Firoozabadi M, Talebi G.Anodal and cathodal pulsed electrical stimulation on skin wound healing in guinea pigs.J Rehabil Res Dev2007;44:611–618.
12. Curtis D, Fallows S, Morris M, McMakin C.The efficacy of frequency specific microcurrent
therapy on delayed onset muscle soreness.J Bodyw Mov Ther2010;14:272–279.
13. Kiernan JA.Histological and histochemical methods: theory and Practice.2001;3rd ed.London:Hodder Arnold Publishers;111–162.
14. Elia A, Charalambous F, Georgiades P.New phenotypic aspects of the decidual spiral artery wall during early post-implantation mouse pregnancy.Biochem Biophys Res Commun2011;416:211–216.
15. Zhou JH, Cao LH, Liu JB, Zheng W, Liu M, Luo RZ, et al..Quantitative assessment of tumor blood flow in mice after treatment with different doses of an antiangiogenic agent with contrast-enhanced destruction-replenishment US.Radiology2011;259:406–413.
16. Pasut A, Oleynik P, Rudnicki MA.Isolation of muscle stem cells by fluorescence activated cell sorting cytometry.Methods Mol Biol2012;798:53–64.
17. Emsley R, Dunn G, White IR.Mediation and moderation of treatment effects in randomized controlled trials of complex interventions.Stat Methods Med Res2010;19:237–270.
18. Crawford RS, Albadawi H, Atkins MD, Jones JJ, Conrad MF, Austen WG Jr, et al..Postischemic treatment with ethyl pyruvate prevents adenosine triphosphate depletion, ameliorates inflammation, and decreases thrombosis in a murine model of hind-limb ischemia and reperfusion.J Trauma2011;70:103–110.
19. Mu X, Peng H, Pan H, Huard J, Li Y.Study of muscle cell dedifferentiation after skeletal muscle
injury of mice with a Cre-Lox system.PLoS One2011;6:e16699–e16707.
20. Lazarenko NN, Gerasimenko MIu.The application of multichannel electrostimulation and nivalin electrophoresis for the rehabilitative treatment of the patient following plastic surgery in the facial region [abstract].Vopr Kurortol Fizioter Lech Fiz Kult2011;5:39–44.
21. Rocheteau P, Gayraud-Morel B, Siegl-Cachedenier I, Blasco MA, Tajbakhsh S.A subpopulation of adult skeletal muscle
stem cells retains all template DNA strands after cell division.Cell2012;148:112–125.
22. Robson LG, Di Foggia V, Radunovic A, Bird K, Zhang X, Marino S.Bmi1 is expressed in postnatal myogenic satellite cells
, controls their maintenance and plays an essential role in repeated muscle regeneration.PLoS One2011;6:e27116–e27126.
23. François S, D’Orlando C, Fatone T, Touvier T, Pessina P, Meneveri R, Brunelli S.Necdin enhances myoblasts survival by facilitating the degradation of the mediator of apoptosis CCAR1/CARP1.PLoS One2012;7:e43335–e43345.
24. Mu X, Urso ML, Murray K, Fu F, Li Y.Relaxin regulates MMP expression and promotes satellite cell mobilization during muscle healing in both young and aged mice.Am J Pathol2010;177:2399–2410.
25. Di Foggia V, Robson L.Isolation of satellite cells
from single muscle fibers from young, aged, or dystrophic muscles.Methods Mol Biol2012;916:3–14.
26. Alfaro LA, Dick SA, Siegel AL, Anonuevo AS, McNagny KM, Megeney LA, et al..CD34 promotes satellite cell motility and entry into proliferation to facilitate efficient skeletal muscle