Investigation of various events occurring in the brain tissue after calvarial defects in rats / Investigación de las alteraciones ocurridas en el tejido cerebral posterior a la creación de defectos en la calvaria de ratas

Bone damage and accidents, traumas can alter people's normal life, and damage the soft tissues. In this study, we aimed to investigate in calvarial defects in rats depending on the severity of cerebral contusion injury occurring in the temporal region. The rats were randomly divided into two groups: group 1 (control group), critical size cranial model with no treatment (n= 10); group 2 (14-day synthetic graft group given 7th day DEXA), critical size cranial model treated with Dexamethasone (0.05 mg/kg intramuscular injection) +Synthetic graft (n= 10) One calvarium defect of 7 mm was made in the parietal bone of each animal under general anesthesia. Calvarial defect results in dilatation of blood vessels, hemorrhage and deterioration was observed in glial fibrillary structures. Additionally, the increase in vascular endothelial growth factor expression showed a positive reaction with glial fibrillary acid protein astrocytes extensions. Apoptotic glial cells stained positive with Bcl-2. Calvarial defects caused by mild brain injury, to be induced by inflammatory cytokines, interrupting glial fibrillary degeneration by affecting the blood brain barrier is thought to promote apoptotic changes.

Daños óseos, accidentes y traumas pueden alterar la vida normal de las personas y dañar los tejidos blandos. Este estudio tuvo como objetivo investigar los defectos de calota en ratas en función de la gravedad de la lesión cerebral que ocurre en una contusión de la región temporal. Las ratas fueron divididas aleatoriamente en dos grupos: al grupo 1 (control), se le realizó un modelo de defecto craneal de tamaño crítico sin tratamiento (n= 10) y al grupo 2, se le realizó un modelo de defecto craneal de tamaño crítico que fue tratado con dexametasona (0,05 mg/kg vía i.m.) + injerto sintético (n= 10) (14 d con injerto sintético y el día 7 se le administró dexametasona). El modelo generó un defecto de 7 mm en el hueso parietal en cada animal, bajo anestesia general. Los defectos craneales produjeron dilatación de los vasos sanguíneos, hemorragias y deterioro en las estructuras gliales fibrilares. Además, el aumento de la expresión del factor de crecimiento vascular endotelial mostró una reacción con las positiva con la proteína ácida fibrilar de la glía el las extensiones de los astrocitos. Las células gliales apoptóticas se tiñeron positivas con Bcl-2. Los defectos de calota causan una lesión cerebral leve, inducidas por citoquinas inflamatorias, las que interrumpen la degeneración glial fibrilar al afectar la barrera hematoencefálica, induciendo cambios apoptóticos.

Exploring anorganic bovine bone granules as osteoblast carriers for bone bioengineering: a study in rat critical-size calvarial defects

It is known that current trends on bone bioengineering seek ideal scaffolds and explore innovative methods to restore tissue function. In this way, the objective of this study was to evaluate the behavior of anorganic bovine bone as osteoblast carrier in critical-size calvarial defects. MC3T3-E1 osteoblast cells (1x10(5) cells/well) were cultured on granules of anorganic bovine bone in 24-well plates and after 24 h these granules were implanted into rat critical-size calvarial defects (group Biomaterial + Cells). In addition, other groups were established with different fillings of the defect: Blood Clot (negative control); Autogenous Bone (positive control); Biomaterial (only granules) and Cells (only MC3T3-E1 cells). After 30 days, the animals were euthanized and the calvaria were technically processed in order to allow histological and morphometric analysis. It was possible to detect blood vessels, connective tissue and newly formed bone in all groups. Particularly in the Biomaterial + Cells group, it was possible to observe a profile of biological events between the positive control group (autogenous bone) and the group in which only anorganic bovine granules were implanted. Altogether, the results of the present study showed that granules of anorganic bovine bone can be used as carrier to osteoblasts and that adding growth factors at the moment of implantation should maximize these results.

Sabe-se que uma das atuais tendências na bioengenharia óssea é procurar um carreador ideal e explorar métodos inovadores para restaurar a função do tecido. Desta forma, nosso objetivo foi avaliar o comportamento do osso bovino inorgânico como carreador de osteoblastos em defeitos ósseos de tamanho crítico em calvária de ratos. Osteoblastos da linhagem MC3T3-E1 (1x10(5) células/poço) foram cultivadas em grânulos de osso bovino inorgânico sob placas de 24 poços e após 24 h esses grânulos foram implantados em defeitos ósseos de tamanho crítico em calvária de ratos. Além deste grupo experimental (Biomaterial + Células), foram estabelecidos outros grupos com diferentes preenchimentos do defeito crítico: coágulo sanguíneo (controle negativo); osso autógeno (controle positivo); Biomaterial (apenas grânulos) e Células (apenas células MC3T3-E1). Após 30 dias, os animais foram eutanasiados e as calvárias foram processadas histotecnicamente, a fim de permitir a análise histológica e morfometria. Nossos resultados mostraram que em todos os grupos avaliados foi possível detectar vasos sanguíneos, tecido conjuntivo e osso neoformado. Em especial para o grupo tratado com Biomaterial + Células, foi possível observar um perfil de eventos biológicos intermediário ao grupo controle positivo (osso autógeno) e o grupo de biomaterial (apenas grânulos inorgânico bovino). Ao todo, nossos resultados mostraram que os grânulos de osso bovino inorgânico podem ser usados como carreador de osteoblastos e que a adição de fatores de crescimento no momento em que ocorre o implante deve maximizar os resultados.

Factors Influencing Regeneration of Calvarial Defects in Rats

An experimental study was done to evaluate factors influencing guided regeneration of bone in standardized calvarial bony defect. An 8 mm circular transosseous calvarial bony defect was made. Various material such as demineralized freeze-dried bone (DFDB), BioMesh , Millipore filter and its combination was placed in the bony defect. A sequential histopathologic, histochemical, immunohistochemical, and histomorphometric studies were done on the guided bone regeneration in the calvarial bony defect. Bone formation was sigificantly enhanced when the DFDB was retained within the bony defect with a protective bioabsorbable membrane. Inframembranous DFDB-filling was required to prevent collapse of the membrane and preserve spaces for bone regeneration. The bioabsorbable membrane should presumably remain intact for longer than at least 5 weeks to facilitate bone regeneration. The new bone formation was dependent on the barrier-effect (preserving secluded spaces) and inflammation-inducing property of membrane, and guiding bone regeneration of the grafts. Macrophages recruited by grafts were partly involved in decrease of bone regeneration via the sequential events of release of fibronectin, chemotactic effect of the fibronectin to fibroblasts, and collagen lay-down.