Osteogenic potential of human dental pulp stem cells cultured onto poly-ε-caprolactone/poly (rotaxane) scaffolds.

BACKGROUND: Bioengineering aims to develop innovative scaffolds to improve cellular activities for tissue regeneration. OBJECTIVES: To evaluate the biological behavior of human dental pulp stem cells (hDPSCs) seeded onto an experimental polymeric-based scaffold comprising poly-ε-caprolactone/poly (rotaxane). MATERIAL AND METHODS: Adhesion, viability, and proliferation as well as alkaline phosphatase (ALP) activity, mineralized nodule formation (alizarin red assay), and expression of genes related to osteogenic differentiation, including ALP, type 1 collagen alpha 1 (COL1A1), Runt-related transcription factor (Runx-2), and osteocalcin (BGLAP/OCN), were evaluated in hDPSCs seeded onto polymeric scaffolds. RESULTS: hDPSCs expressed typical levels of mesenchymal stem cell surface markers. Cell growth increased upon cultivation on polymeric blend scaffold and the cells gained osteoblast-like appearance. Fourteen days after seeding hDPSCs on the scaffolds, irrespective to the culture medium used (clonogenic or mineralization medium), the cells presented ALP activity higher than that of control cells grown in clonogenic medium. The cells cultivated in mineralization medium on the scaffold showed significantly higher expression of all genes than the control cells, except for BGLAP gene expression. At 21 days, the group cultivated on the scaffold and mineralization medium showed maximum level of mineralization. SIGNIFICANCE: Poly-ε-caprolactone/poly (rotaxane) blend is noncytotoxic to hDPSCs and improved genomic and functional osteogenic differentiation. Thus, poly-ε-caprolactone/poly (rotaxane) blend may serve as a promising bioactive biomaterial for bone tissue bioengineering.

In vivo biocompatibility of nanostructured Chitosan/Peo membranes / Biocompatibilidade in vivo de membranas nanoestruturadas de Quitosana/Peo

Electrospinning is a technique that allows the preparation of nanofibers from various materials. Chitosan is a natural and abundant easily obtained polymer, which, in addition to those features, proved to be biocompatible. This work used nanostructured chitosan and polyoxyethylene membranes as subcutaneous implants in Wistar rats to evaluate the biocompatibility of the material. Samples of the material and tissues adjacent to the implant were collected 7, 15, 30, 45 and 60 days post-implantation. Macroscopic integration of the material to the tissues was observed in the samples and slides for histopathological examination that were prepared. It was noticed that the material does not stimulate the formation of adherences to the surrounding tissues and that there is initial predominance of neutrophilia and lymphocytosis, with a declining trend according to the increase of time, featuring a non-persistent acute inflammatory process. However, the material showed fast degradation, impairing the macroscopic observation after fifteen days of implantation. It was concluded that the material is biocompatible and that new studies should be conducted, modifying the time of degradation by changes in obtaining methods and verifying the biocompatibility in specific tissues for biomedical applications.

A eletrofiação é uma técnica que permite a preparação de nanofibras mediante o uso de diversos materiais. A quitosana é um polímero natural, abundante e de fácil obtenção, que, além dessas características, demonstrou ser biocompatível. Este trabalho utilizou membranas nanoestruturadas de quitosana e polióxido de etileno como implantes subcutâneos em ratos Wistar para avaliar a biocompatibilidade do biomaterial. As amostras do material e de tecidos adjacentes ao implante foram retiradas sete, 15, 30, 45 e 60 dias pós-implantação para a observação da integração macroscópica do material aos tecidos e para a preparação de lâminas para exame histopatológico. Verificou-se que o material não estimula a formação de aderências com os tecidos circunvizinhos e que há predominância inicial de neutrofilia e linfocitose, que tendem a decrescer em razão do aumento do tempo, caracterizando um processo inflamatório agudo não persistente. No entanto, o material apresentou degradação rápida, não sendo possível observá-lo macroscopicamente após 15 dias de implantação. Concluiu-se que o material é biocompatível, o que indica que novos estudos devem ser conduzidos, com modificação do tempo de degradação por alterações nos métodos de obtenção e verificação da biocompatibilidade em tecidos específicos para aplicações biomédicas.

Electrospun membranes of poly(lactic acid) (PLA) used as scaffold in drug delivery of extract of Sedum dendroideum.

Biomaterials nanofibrous electrospun with biodegradable polymers have the advantage of the similarity to natural extracellular matrices, showing promising as scaffolds for application in tissue engineering. Sedum dendroideum is a phytotherapic drug that stands out for its healing properties and anti-inflammatory. This study presents the efficacy of PLA electrospun membranes used as support S. dendroideum extract releasing on excisional skin lesions of Wistar rats. The PLA porous membranes, which are nonwoven fibrous mats, were obtained by electrospinning using a conventional apparatus with a flat collector. The animals were randomly divided into nine groups: control (C), animals treated with electrospun membranes of PLA (M), animals treated with extract of S. dendroideum dissolved in saline (F), animals treated with membranes of PLA with 10% S. dendroideum (MF10), animals treated with membranes of PLA with 25% S. dendroideum (MF25). Tissue samples were taken after 2, 6 and 10 days after surgery and were subjected to structural analysis and morphology. The experimental observations showed the application of the phytotherapic incorporated in the membrane promoted a significant response regarding the number of inflammatory cells, percentage of mature collagen fibers and epithelium birrefringent in thickness excisional skin lesions in Wistar rats. It was also demonstrated that the application of the PLA membranes without the extract promoted similar responses tissues.

Effect of clay content and speed screw rotation on the crystallization and thermal behaviors of recycled PET/clay nanocomposites.

Nanocomposites of recycled poly(ethylene terephthalate) (rPET) containing 2.5 wt% and 5.0 wt% of montmorillonite modified with organophilic quaternary ammonium salt (DELLITE 67G) were prepared by melt compounding using a co-rotating twin-screw type extruder with two organoclay contents were used: 2.5 wt% and 5.0 wt% and were prepared using two different rotation speeds: 150 and 250 rpm. Thermal characterization (analysis) of the nanocomposites was performed using differential scanning calorimetry (DSC) analysis. The results from DSC measurements showed that the addition of organoclay affects recycled PET's crystallization for two screw rotation speeds studies. The nucleating effect of organoclay was investigated. Morphological analysis using Transmission Electron Microscopy (TEM) revealed the presence of fully exfoliated clay platelets in samples prepared at 150 rpm.