Fibrin biopolymer as scaffold candidate to treat bone defects in rats

Bone tissue repair remains a challenge in tissue engineering. Currently, new materials are being applied and often integrated with live cells and biological scaffolds. The fibrin biopolymer (FBP) proposed in this study has hemostatic, sealant, adhesive, scaffolding and drug-delivery properties. The regenerative potential of an association of FBP, biphasic calcium phosphate (BCP) and mesenchymal stem cells (MSCs) was evaluated in defects of rat femurs. Methods: Adult male Wistar rats were submitted to a 5-mm defect in the femur. This was filled with the following materials and/or associations: BPC; FBP and BCP; FBP and MSCs; and BCP, FBP and MSCs. Bone defect without filling was defined as the control group. Thirty and sixty days after the procedure, animals were euthanatized and subjected to computed tomography, scanning electron microscopy and qualitative and quantitative histological analysis. Results: It was shown that FBP is a suitable scaffold for bone defects due to the formation of a stable clot that facilitates the handling and optimizes the surgical procedures, allowing also cell adhesion and proliferation. The association between the materials was biocompatible. Progressive deposition of bone matrix was higher in the group treated with FBP and MSCs. Differentiation of mesenchymal stem cells into osteogenic lineage was not necessary to stimulate bone formation. Conclusions: FBP proved to be an excellent scaffold candidate for bone repair therapies due to application ease and biocompatibility with synthetic calcium-based materials. The satisfactory results obtained by the association of FBP with MSCs may provide a more effective and less costly new approach for bone tissue engineering.(AU)

Sex-specific effects of Eugenia punicifolia extract on gastric ulcer healing in rats.

AIM: To evaluate the sex-specific effects of a hydroalcoholic extract from Eugenia punicifolia (HEEP) leaves on gastric ulcer healing. METHODS: In this rat study involving males, intact (cycling) females, and ovariectomized females, gastric ulcers were induced using acetic acid. A vehicle, lansoprazole, or HEEP was administered for 14 d after ulcer induction. Body weight was monitored throughout the treatment period. At the end of treatment, the rats were euthanized and the following in vivo and in vitro investigations were performed: macroscopic examination of the lesion area and organ weights, biochemical analysis, zymography, and evaluation of protein expression levels. Additionally, the concentration-dependent effect of HEEP was evaluated in terms of subacute toxicity and cytotoxicity. RESULTS: Compared to the vehicle, HEEP demonstrated a great healing capacity by substantially reducing the ulcerative lesion area in males (52.44%), intact females (85.22%), and ovariectomized females (65.47%), confirming that HEEP accelerates the healing of acetic acid-induced gastric lesions and suggesting that this effect is modulated by female sex hormones. The antiulcer effect of HEEP was mediated by prostaglandin E2 only in male rats. Overall, the beneficial effect of HEEP was the highest in intact females. Notably, HEEP promoted the expression of vascular endothelial growth factor (intact vs ovariectomized females) and decreased the expression of Caspase-8 and Bcl-2 (intact female vs male or ovariectomized female). Additionally, HEEP enhanced fibroblast proliferation and migration into a wounded area in vitro, confirming its healing effect. Finally, no sign of subacute toxicity or cytotoxicity of HEEP was observed. CONCLUSION: In gastric ulcers, HEEP-induced healing (modulated by female sex hormones; in males, mediated by prostaglandin) involves extracellular matrix remodeling, with gastric mucosa cell proliferation and migration.

Avaliação da fosfatase alcalina óssea e hepática em gatos com tirotoxicose induzida / Evaluation of bone and liver alkaline phosphatase in cats with induced

A tirotoxicose é caracterizada pelas excessivas concentrações séricas dos hormônios tiroidianos, podendo desencadear graves alterações no metabolismo ósseo, sendo a elevação da fosfatase alcalina total uma alteração laboratorial freqüentemente observada no hipertiroidismo felino. O aumento global dos níveis séricos de fosfatase alcalina pode ser decorrente de diferentes isoenzimas e, no caso do hipertiroidismo em humanos, as isoenzimas de origem óssea e hepática apresentam-se comumente elevadas. A partir da avaliação da bioquímica sérica de oito gatos com tirotoxicose induzida e elevação da fosfatase alcalina associada, o presente trabalho demonstra um aumento significativamente maior dos níveis séricos da fosfatase alcalina de origem óssea quando comparado com a isoenzima de origem hepática. Conclui-se que as alterações no metabolismo ósseo foram as principais responsáveis pelo aumento da fosfatase alcalina nos gatos com tirotoxicose induzida

Thyrotoxicosis, characterized by excessive serum levels of thyroidhormones, can cause serious effects in bone metabolism, elevating the total alkaline phosphatase, which is a frequent laboratorial alteration observed in feline hyperthyroidism. A rise in total serum levels of alkaline phosphatase can be caused by different isoenzymes, and in human hyperthyroidism, bone and hepatic isoenzymes are commonly increased. After serum biochemical evaluation of eight cats with induced thyrotoxicosis and associated elevation of alkaline phosphatase, the present paper shows a significant elevation of bone isoenzyme serum levels when compared with hepatic isoenzyme. It was possible to conclude that bone metabolism alterations were the main responsible for the increase of serum alkaline phosphatase in cats with induced thyrotoxicosis.

Heart failure alters matrix metalloproteinase gene expression and activity in rat skeletal muscle.

Heart failure is associated with a skeletal muscle myopathy with cellular and extracellular alterations. The hypothesis of this investigation is that extracellular changes may be associated with enhanced mRNA expression and activity of matrix metalloproteinases (MMP). We examined MMP mRNA expression and MMP activity in Soleus (SOL), extensor digitorum longus (EDL), and diaphragm (DIA) muscles of young Wistar rat with monocrotaline-induced heart failure. Rats injected with saline served as age-matched controls. MMP2 and MMP9 mRNA contents were determined by RT-PCR and MMP activity by electrophoresis in gelatin-containing polyacrylamide gels in the presence of SDS under non-reducing conditions. Heart failure increased MMP9 mRNA expression and activity in SOL, EDL and DIA and MMP2 mRNA expression in DIA. These results suggest that MMP changes may contribute to the skeletal muscle myopathy during heart failure.