Organization of collagen bundles during tendon healing in rats treated with L-NAME

Abstract

The Achilles tendon can support high tension forces and may experience lesions. The damaged tissue does not regenerate completely, with the organization and mechanical properties of the repaired tendon being inferior to those of a healthy tendon. Nitric oxide (NO) plays an important role in wound repair. We have examined the structural reorganization and repair in Achilles tendon after injury in rats treated with the NO synthase inhibitor L-NAME. The right Achilles tendon of male Wistar rats was partially transected. One group of rats was treated with L-NAME (~300 mg/kg per day, given in drinking water) for 4 days prior to tendon sectioning and throughout the post-operative period. Control rats received water without L-NAME. The tendons were excised at 7, 14, and 21 days post-injury and used to quantify hydroxyproline and for mechanical tests. Tendons were also processed for histomorphological analysis by polarized light microscopy, which showed that the collagen fibers were disorganized by day 7 in non-treated and L-NAME-treated rats. In non-treated rats, the organization of the extracellular matrix was more homogeneous by days 14 and 21 compared with day 7, although this homogeneity was less than that in normal tendon. In contrast, in injured tendons from L-NAME-treated rats, the collagen fibers were still disorganized on day 21. Tendons from treated rats had more hydroxyproline but lower mechanical properties compared with those from non-treated rats. Thus, NO modulates tendon healing, with a reduction in NO biosynthesis delaying reorganization of the extracellular matrix, especially collagen.

Structural and biochemical alterations during the healing process of tendons treated with Aloe vera

“…Studies have shown that there is a formation of granulation tissue in the tendon to stabilize the injured area, which is followed by scar formation in the later stages of the healing process (Favata et al, 2006). The collagen is disorganized in the granulation tissue (Tomiosso et al, 2009), corroborating our results that showed complete disorganization of collagen fibers, especially in the acute phase of the repair process. Importantly, there are relatively dense fibrils that are helically intertwined in the transected area, whose function is related to the reorganization of newly formed collagen fibers in fascicles, as described in rat tail tendons and chordae tendineae (Vidal, 1995;Vidal and Mello, 2009).…”

“…The transected region of both plant-treated and non-treated groups analyzed on the 7th day after the lesion, was characterized as an area under a phagocytosis process and where the damaged collagen fibers are completely digested, as observed by Tomiosso et al (2009). These changes could have been caused by the inflammatory process that starts immediately after injury (Murphy et al, 1994a(Murphy et al, , 1994bOakes, 2003), by the change in the intensity of biomechanical stress that affects the tissue after injury or both.…”

“…A longitudinal incision was made in the skin to expose the calcaneal tendon, and the partial transverse transection was performed in the tension region of the tendon, located an approximate distance of 4 mm from the tendon's insertion into the calcaneus bone (Tomiosso et al, 2009). To cover completely the transection region of the tendon, 32 mg of the 50% A. vera ointment was applied at the site of the tendon transection prior to the suture of the skin.…”

“…Although several treatments for tendon lesions have been proposed in recent years, tendon lesions are still a serious clinical issue because the site of the injury becomes a region with a high incidence of recurrent rupture. After lesions occur, the structural organization and composition of the tendon are not completely restored and become biomechanically weakened (Mello et al, 1975;Tomiosso et al, 2009;Ni et al, 2011).…”

Efeito do ultrassom terapêutico sobre as propriedades mecânicas do gastrocnêmio em ratos

“…Estes resultados corroboram com o trabalho de Oliveira et al 16 , que também não verificou influências experimentais sobre o ALP e o ALM, entre os grupos equivalentes. A literatura apresenta outros trabalhos que, de maneira semelhante, não encontraram diferenças no alongamento suportado entre seus grupos experimentais, apesar de observarem diferenças nas demais propriedades 17,20,28 . Embora os autores não ofereçam explicação para este achado, é plausível admitir que, entre tecidos moles de dimensões reduzidas, a diferença entre medidas do grau de alongamento tende a se tornar pouco expressiva.…”