Histological and radiographic evaluation of the muscle tissue of rats after implantation of bone morphogenic protein (rhBMP-2) in a scaffold of inorganic bone and after stimulation with low-power laser light.

Objective: The present study histologically and radiologically evaluates the muscle tissue of rats after implantation of bone morphogenic protein (rhBMP-2) in a natural inorganic bone mineral scaffold from a bull calf femur and irradiation with low-power light laser. Materials and Methods: The right and left hind limbs of 16 rats were shaved and an incision was made in the muscle on the face corresponding to the median portion of the tibia, into which rhBMP-2 in a scaffold of inorganic bone was implanted. Two groups of limbs were formed: control (G1) and laser irradiation (G2). G2 received diode laser light applied in the direction of the implant, at a dose of 8 J/cm2 for three minutes. On the 7th, 21st, 40th and 112th days after implantation, hind limbs of 4 animals were radiographed and their implants removed together with the surrounding tissue for study under the microscope. The histological results were graded as 0=absence, 1=slight presence, 2=representative and 3=very representative, with regard to the following events: formation of osteoid structure, acute inflammation, chronic inflammation, fibrin deposition, neovascularization, foreign-body granuloma and fibrosis. Results: There were no statistically significant differences in these events at each evaluation times, between the two groups (P>0.05; Mann-Whitney test). Nevertheless, it could be concluded that the natural inorganic bone matrix with rhBMP-2, from the femur of a bull calf, is a biocompatible combination. Conclusions: Under these conditions, the inductive capacity of rhBMP-2 for cell differentiation was inhibited. There was a slight acceleration in tissue healing in the group that received irradiation with low-power laser light.

Effect of 650 nm low-power laser on bone morphogenetic protein in bone defects induced in rat femors

PURPOSE:To investigate the influence of 650 nm GaAlAs laser on the action of bone morphogenetic protein (BMP) in bone defects produced in rat femurs. METHODS: The sample consisted of 12 male albino Wistar rats (Rattus norvegicus). The animals were randomly divided into four experimental groups. After undergoing anesthesia, the fur was removed from the lateral face of the right thigh and surgical dissection was performed to view the femur region. A bone defect was created using a spherical diamond-tipped drill bit. In groups 1 and 2, the defect was filled with a paste of Gen-Tech bone-inducing substance. The animals were treated with GaAlAs laser, at a predetermined dose of joules/cm² for 80 seconds, over an area of 1 cm². Groups 2 and 4 were used as controls. Bone samples were removed to perform histological procedures and morphometric analyses on the 7th, 14th and 21st days after the operation. The results obtained were subjected to statistical analysis using ANOVA variance according to two criteria, with four repetitions, followed by the post hoc t test. The rejection level for the nullity hypothesis was 0.05 or 5 percent (alpha <= 0.05). RESULTS: In comparisons between G1, G2, G3 and G4, p = 0.024 was observed. In statistical comparisons using the t test for paired samples, only G1 vs. G4 presented a statistically significant result (p = 0.021). CONCLUSION: The association of low-power laser application and Gen-Tech bone-inducing substance achieved a better result than laser application alone or BMP use alone.

OBJETIVO: Este trabalho tem como objetivo estudar comparativamente a influência do laser AsGaAl de 650nm sobre a ação das proteínas morfogenéticas ósseas( BMP) em defeitos ósseos produzidas em fêmures de ratos. METODOLOGIA: Utilizamos uma amostra composta por 12 ratos machos (Rattus norvegicus), de linhagem Wistar albino, mantidos confinados em caixas com temperatura ambiente constante e iluminação adequada. Os animais foram divididos aleatoriamente em 4 grupos experimentais. Após o procedimento anestésico, foi realizada a retirada dos pelos da face lateral da coxa direita, seguida de procedimento cirúrgico para permitir a visualização da região. Foi realizado um defeito ósseo empregando brocas diamantadas do tipo esférica. Nos grupos 1 e 2 o defeito foi preenchido com uma pasta formada por substância osteoindutora Gen - Tech. Os animais foram tratados com o Laser GaAlAs, com dose pré-determinada de 4 joules/cm² e tempo de 80 segundos para uma área de 1cm². Os grupos 2 e 4 foram adotados como grupo-controle. As amostras do osso foram retiradas para realização de procedimento histológico e análise morfométrica nos 7°,14°e 21° dias de pós-operatório. Os resultados obtidos foram submetidos à análise estatística pela variância ANOVA segundo dois critérios, com quatro repetições. Seguido do post hoc test de t teste, com nível de rejeição da hipótese de nulidade de 0,05 ou 5 por cento (alfa <= 0,05). RESULTADOS: Na comparação entre G1, G2, G3 e G4, observou-se: (P = 0,024) e durante a comparação estatística através do teste "t" para amostras pareadas apenas o cruzamento entre Grupo 1 vs. o Grupo 4 apresentou, resultado estatisticamente significante com (p=0,021). CONCLUSÃO: Concluímos que a associação da aplicação do laser de baixa potência e a substância osteoindutora Gen Tech alcançou melhor resultado do que do que a aplicação de laser ou apenas o uso das BMPs.