RESUMEN
OBJECTIVE: To determine tendon stump changes following unrepaired Achilles tendon lacerations in an animal model. STUDY DESIGN: An experimental study. PLACE AND DURATION OF STUDY: King Saud University, Riyadh, Saudi Arabia, from October 2013 to January 2014. METHODOLOGY: Arabbit model was developed and studied tendon retraction and histological changes in the proximal and distal stumps following transection of the Achilles tendon. RESULTS: Over a period of 12 weeks, retraction of the distal tendon stump was minimal (2 - 3 mm). In contrast, retraction of the proximal tendon stump peaked to reach 6 mm at 4 weeks post-injury and plateaued to reach 7 - 8 mm at the 12-week interval. CONCLUSION: Following complete transection of the Achilles tendon, tendon retraction correlated with the density of myofibroblast expression within the tendon stump. Further research is needed to investigate the pathophysiology of these findings.
Asunto(s)
Tendón Calcáneo/lesiones , Tendón Calcáneo/patología , Laceraciones/etiología , Traumatismos de los Tendones/patología , Tendón Calcáneo/cirugía , Animales , Conejos , Traumatismos de los Tendones/cirugíaRESUMEN
Generally speaking, the excessive expression of myofibroblasts is associated with excessive collagen production. One exception is seen in patients and animal models of Ehlers-Danlos syndrome type IV in which the COL3A1 gene mutation results in reduced collagen III but with concurrent increased myofibroblast expression. This paradox has not been examined with the use of external drugs/modalities to prevent hypertrophic scars. In this paper, we injected the rabbit ear wound model of hypertrophic scarring with two doses of a protein called nAG, which is known to reduce collagen expression and to suppress hypertrophic scarring in that animal model. The higher nAG dose was associated with significantly less collagen III expression and concurrent higher degree of myofibroblast expression. We concluded that collagen III content of the extracellular matrix may have a direct or an indirect effect on myofibroblast differentiation. However, further research is required to investigate the pathogenesis of this paradoxical phenomenon.
Asunto(s)
Colágeno Tipo III/metabolismo , Miofibroblastos/metabolismo , Enfermedades de la Piel/metabolismo , Heridas y Lesiones/metabolismo , Animales , Diferenciación Celular/fisiología , Cicatriz Hipertrófica/metabolismo , Modelos Animales de Enfermedad , Síndrome de Ehlers-Danlos/metabolismo , Matriz Extracelular/metabolismo , Humanos , ConejosRESUMEN
nAG (newt-Anterrior Gradient) protein is the key mediator of regrowth of amputated limbs in salamanders. In a previous work in our lab, a new nAG gene (suitable for humans) was designed and cloned. The cloned vector was transfected into primary human fibroblasts. The expression of nAG in human primary fibroblasts was found to suppress collagen expression. The current study shows that local injection of recombinant nAG reduces scar hypertrophy in the rabbit ear model. This is associated with lower scar elevation index (SEI), lower levels of collagen I & III, higher levels of MMP1, and a higher degree of scar maturation in experimental wounds compared to controls.