The impact of skeletal muscle injury on the expression of laminin and its role in regeneration

Abstract

Background: Laminins are high-molecular-weight proteins in the extracellular matrix; it is a major component of the basal lamina, influencing cell differentiation, migration, and adhesion. Laminin affects cell growth, besides effects in wound healing and embryonic development. Objectives: The present study aims to assess the histological changes taking place during skeletal muscle healing. Methods: The extensor digitorum longus muscle of 45 male rabbits was set as a skeletal muscle injury model and examined 3&6 weeks after initiation of injury. These animals were divided into three groups control (A) group with no injury, group (B) at 3rd post-injury week, group (C) at 6th post-injury week. The muscle tissues were prepared and examined histologically using H&E and immunohistochemically using Laminin antibodies. Aperio image scope software is used to analyze immunohistochemical reactivity quantitatively. The degeneration and regeneration process were overlapping with each other both in time and cellular morphological changes. Early myoblast-like cell appearance and new myotube formation were recorded during the 3rd week. By the end of the 6th-week postoperatively, the muscle histological maturation and muscle fascicles were noticed. Results: Immunohistochemical reactivity of Laminin antibody showed an intense reactivity in the 3rd-week group while a less intense reactivity in the control and 6th-week groups'. A quantitative assessment of Laminin using Aperio soft wear showed that the 3rd-week group has an intensity of 0.724±0.03 pixel, while the 6th week's group was 0. 321±0.02 pixel and the control group was 0.293±0.02 pixel. The differences were statistically significant, P-value ≤0.0001. Conclusion: The process of regeneration is a dynamic type where degeneration and regeneration superimposed each other.