ABSTRACT
The application of electrical stimulation can lead to a greater and faster increase in the rate of wound healing, especially when applying the cathedral [negative] stimulation for the first week, followed by the anodal [positive] polarity for the rest of the treatment period. The present work aimed to study the effect of polarity reversal of microelectrical current stimulation [MES] on the healing process in an experimentally induced Achilles tendon injury in rats. Forty three male albino rats were used in this study; they were classified into group I [control group] and group II [experimentally injured group], which was further classified into subgroups, I, II, III and IV. Subgroup I represents the injured tendon without MES treatment, whereas subgroups II, III and IV represent the MES-treated ones. The obtained tendon sections were subjected to H and E staining. Masson's trichrome stain, and immunohistochemical staining for alpha smooth muscle actin [alpha SMA], followed by morphometric study and statistical analysis. Subgroup I showed signs of inflammation, a few thin irregularly arranged collagen, active fibroblasts that start to align in rows on the regenerating collagen bundles, and alpha SMA immunoreactivity. In anodal-treated tendons, signs of inflammation had started to disappear; collagen fibers appeared thin and irregularly arranged, active fibroblasts were obviously observed and minimal alpha SMA immunoreactivity were recorded only in subgroup II. Cathodal-treated tendons showed rapid disappearance of cellular infiltration; most collagen fibers appeared regularly arranged with mature fibrocytes in between and multiple avoid alpha SMA immunoreactive myofibroblasts were maximally observed in subgroup II. alpha SMA was suggested to play a role in wound healing due to its high immunoreactivity in myofibroblasts during wound healing. Moreover, the application of electrical stimulation by applying cathodal [negative] stimulation for the first week, followed by anodal [positive] polarity for the rest of the treatment period may lead to better repaired tissue due to myofibroblast directional attraction to the cathode, especially when applied for 4-week duration