ABSTRACT
Introduction: Mouse models of emphysema are important tools for testing different therapeutic strategies. The aim of this study was to develop a mouse model of emphysema induced by different doses of elastase in order to produce different degrees of severity. Methods: Thirty female mice (C57BL/6) were used in this study. Different doses of porcine pancreatic elastase were administered intratracheally once a week for four weeks, as follows: 0.1 U (n=8), 0.15 U (n=7), and 0.2 U (n=7). Control mice (n=8) received 50 microL of sterile saline solution intratracheally. Lung mechanics were analyzed by plethysmography. Mean linear intercept and volume fraction occupied by collagen and elastic fibers were determined. Results: An increase in lung resistance was observed with 0.2 U of elastase [median (P-25-P75): 2.02 (1.67; 2.34) cmH2O.s/mL], as well as a decrease in tidal volume and minute ventilation. Peak expiratory flow increased significantly in the groups treated with 0.15 U and 0.2 U of elastase. Mean linear intercept was higher with 0.15 U and 0.2 U of elastase, with destruction of alveolar walls [median (P-25-P75): 30.31 (26.65-43.13) microm and 49.49 (31.67-57.71) microm respectively]. The volume fraction occupied by collagen and elastic fibers was lower in the group receiving 0.2 U of elastase. Conclusion: Four intratracheal instillations of 0.2 U of elastase once a week induced changes in lung function and histology, producing an experimental model of severe pulmonary emphysema, whereas 0.15 U resulted in only histological changes.
Subject(s)
Animals , Mice , Pancreatic Elastase/administration & dosage , Pancreatic Elastase/toxicity , Pulmonary Emphysema/chemically induced , Pulmonary Emphysema/metabolismABSTRACT
Este trabalho tem como objetivo apresentar um novo modelo experimental de reconstrução em falha mandibular em coelhos. Foram utilizados 14 animais, nos quais, em uma primeira etapa, extraiu-se cirurgicamente o dente incisivo inferior esquerdo permanente. Após um período de 50 dias para o preenchimento ósseo do alvéolo dentário, foi realizada a cirurgia. Inicialmente, coletou-se 10x5x5mm de enxerto ósseo autógeno da crista ilíaca e, em seguida, foi procedida uma falha mandibular parcial de mesmo tamanho, que foi preenchida com o enxerto e fixada com microplaca de titânio. Os coelhos foram submetidos a avaliações clínicas e radiográficas, sendo sete submetidos a eutanásia aos 15 dias e os demais aos 30 dias para análise macro e microscópica. A ingestão de água e ração não foi comprometida, e os animais não apresentaram algia, dificuldade de mastigação e de apreensão. Somente um animal apresentou rejeição a um parafuso, sem ocorrer o deslocamento da placa nem do enxerto. Esse método mostrou-se eficaz como modelo experimental de reconstrução em falha mandibular de coelhos, demonstrando a evolução cicatricial óssea do enxerto por meio dos exames radiográficos, macroscópicos e microscópicos aos 15 e 30 dias.
This paper aims to present a new experimental model of mandibular defect reconstruction in rabbits. It was used 14 animals, in which, in a first stage the left permanent inferior incisive tooth was extracted surgically. After a 50 days period for the bone to fulfill the dentary alveolus, surgery was performed. At first, a 10x5x5mm autograft was removed form the iliac crest, following a partial mandibular failure in the bone with the same auto graft size which was filled with the graft and fixed using titanium microplate. The rabbits were submitted to clinical and radiographic evaluation and 7 of them were euthanasiated at 15 days and the other 7 at 30 days to macro and microscopic analysis. The water and commercial food ingestion was not compromised, and the animals did not showed any chewing or apprehension difficulties, neither pain. Only one animal presented rejection to one screw, without occurring micro plate nor auto graft dislocation. This method showed to be efficient for an experimental model of reconstruction in mandibular defects of rabbits, demonstrating a healing evolution of the graft through radiographic, macroscopic and microscopic exams in 15th and 30th days.
ABSTRACT
Stem cells can be classified as embryonic stem (ES) cells or adult stem cells considering their origin. If plasticity is considered, stem cells can be classified as totipotent, when stem cells retain the ability to give rise to an entire new organism. When stem cells lose this capacity, cells are named pluripotent stem cells, which can give rise to almost all mature cell types that compound an organism. Totipotent and pluripotent stem cells can be obtained from developing early-stage embryos. Multipotent is the group of adult stem cells with restricted plasticity. These cells can differentiate into a defined cell type related with a specific organ or tissue. ES cells can be propagated in vitro under undifferentiated system or with a series of protocols to induce cell differentiation. On the other hand, multipotent adult stem cells cannot be maintained in vitro in an undifferentiated form, except for a special class of adherent adult stem cells named mesenchimal stem cells, which can be expanded in vitro conserving their undifferentiated characteristics. Considering the ability to generate teratomas, ES cells were not used in experimental in vivo cell transplant. On the other hand, several experimental adult stem cells transplants have been performed with controversial results
Considerando a origem de obtenção, as células-tronco podem ser classificadas como células-tronco embrionárias (ES) ou como células-tronco adultas. Mas, se a plasticidade for considerada, as células-tronco podem ser classificadas como células totipotentes, quando as células-tronco preservam a capacidade de dar origem a um novo indivíduo completo. Quando as células-tronco perdem esta capacidade, passam a ser classificadas como células-tronco pluripotentes, que podem dar origem a praticamente todos os tipos celulares maduros que compõem um organismo. Células-tronco totipotentes e pluripotentes podem ser obtidas de estágios embrionários iniciais. O grupo de células-tronco que apresenta plasticidade restrita é denominado de multipotente. Estas células podem se diferenciar em determinado tipo celular comprometido com um órgão ou tecido específico. Células ES podem ser expandidas in vitro, mantendo sua forma indiferenciada, ou podem ser submetidas a uma série de protocolos, que irão induzir diferenciação in vitro. Por outro lado, as células-tronco adultas multipotentes não podem ser mantidas in vitro na forma indiferenciada, exceto uma subpopulação de célulastronco adultas aderentes, denominadas células-tronco mesenquimais, que podem ser mantidas in vitro na forma indiferenciada. Considerando a capacidade de gerar teratomas, as células ES não foram utilizadas para transplante celular experimental in vivo. Além disso, várias cirurgias de transplantes experimentais com células-tronco adultas têm sido realizadas, porém apresentando resultados controversos