RESUMEN
Tissue engineering represents a promising alternative for reconstructive surgical procedures especially for the repair of bone defects that do not regenerate spontaneously. The present study aimed to evaluate the effects of the elastin matrix (E24/50 and E96/37) incorporated with hydroxyapatite (HA) or morphogenetic protein (BMP) on the bone repair process in the distal metaphysis of rat femur. The groups were: control group (CG), hydrolyzed elastin matrix at 50°C/24h (E24/50), E24/50 + HA (E24/50/HA), E24/50 + BMP (E24/50/BMP), hydrolyzed elastin matrix at 37°C/96h (E96/37), E96/37 + HA (E96/37/HA), E96/37 + BMP (E96/37/BMP). Macroscopic and radiographic analyses showed longitudinal integrity of the femur in all groups without fractures or bone deformities. Microtomographically, all groups demonstrated partial closure by mineralized tissue except for the E96/37/HA group with hyperdense thin bridge formation interconnecting the edges of the ruptured cortical. Histologically, there was no complete cortical recovery in any group, but partial closure with trabecular bone. In defects filled with biomaterials, no chronic inflammatory response or foreign body type was observed. The mean volume of new bone formed was statistically significant higher in the E96/37/HA and E24/50 groups (71.28 ± 4.26 and 66.40 ± 3.69, respectively) than all the others. In the confocal analysis, it was observed that all groups presented new bone markings formed during the experimental period, being less evident in the CG group. Von Kossa staining revealed intense calcium deposits distributed in all groups. Qualitative analysis of collagen fibers under polarized light showed a predominance of red-orange birefringence in the newly regenerated bone with no difference between groups. It was concluded that the E24/50 and E96/37/HA groups promoted, with greater speed, the bone repair process in the distal metaphysis of rat femur.
Asunto(s)
Regeneración Ósea/efectos de los fármacos , Fémur/lesiones , Osteogénesis/efectos de los fármacos , Ingeniería de Tejidos , Andamios del Tejido/química , Animales , Proteínas Morfogenéticas Óseas/administración & dosificación , Modelos Animales de Enfermedad , Durapatita/administración & dosificación , Elastina/administración & dosificación , Fémur/diagnóstico por imagen , Fémur/efectos de los fármacos , Humanos , Masculino , Ratas , Factores de Tiempo , Microtomografía por Rayos XRESUMEN
Lesions of the anterior cruciate ligament are extremely common and frequently demand surgical treatment in order to avoid disabling sequels. The use of a central one-third of the patellar tendon as an autograft for surgical reconstruction of a damaged cruciate ligament is common. Although several investigations in human and animal models have demonstrated long-term graft viability, there have been cases of loosening and rupture of the graft. In these occasions, a new substitute for the torn structure must be found. Owing to its inherent accessibility, the patellar tendon has been elected one of the choices of donor tissue. In order to evaluate the characteristics of the remaining scar, we performed a histochemical and ultrastructural study using biopsy material obtained from the central one-third of the donor tendon of 8 patients. This material was analyzed by comparing the ultrastructural picture with the results obtained using the specific method for collagen-containing fibers (Picrosirius-polarization) by light microscopy; four normal patellar tendons were used as controls. Despite the resemblance with the normal tissue, our results show that the healed tissue does not restore the tendon ad integrum, neither at the light microscopic nor at the electron microscopic levels. Structural differences can be responsible for biomechanical alterations. Impaired biomechanical properties can, at least partly, explain some of the clinical complications observed in patients submitted to this surgical technique. However, without performing biomechanical studies in this kind of tendons, we are neither allowed to encourage nor to reject the use of scars as donor tissue for a second surgery.