Estudio de biocompatibilidad de matrices poliméricas combinadas, responsivas al pH, con aplicación en Ingeniería de Tejido Óseo / Biocompatibility study of combined pH-responsive polymeric matrices with application in Bone Tissue Engineering

El presente trabajo muestra la obtención de un material a partir de un polímero sintético (TerP) y otro natural, mediante entrecruzamiento físico y su caracterización fisicoquímica y biológica, con el fin de emplearlos para regeneración de tejido óseo. Las membranas fueron obtenidas por la técnica de evaporación del solvente y caracterizadas por espectroscopia FTIR, ensayos de hinchamiento, medidas de ángulo de contacto y microscopia electrónica de barrido (SEM). Se encontró que la compatibilidad entre los polímeros que la constituyen es estable a pH fisiológico y que, al incorporar mayor cantidad del TerP a la matriz, esta se vuelve más hidrofóbica y porosa. Además, teniendo en cuenta la aplicación prevista para dichos materiales, se realizaron estudios de biocompatibilidad y citotoxicidad con células progenitoras de médula ósea (CPMO) y células RAW264.7, respectivamente. Se evaluó la proliferación celular, la producción y liberación de óxido nítrico (NO) al medio de cultivo durante 24 y 48 horas y la expresión de citoquinas proinflamatorias IL-1ß y TNF-α de las células crecidas sobre los biomateriales variando la cantidad del polímero sintético. Se encontró mayor proliferación celular y menor producción de NO sobre las matrices que contienen menos proporción del TerP, además de poseer una mejor biocompatibilidad. Los resultados de este estudio muestran que el terpolímero obtenido y su combinación con un polímero natural es una estrategia muy interesante para obtener un biomaterial con posibles aplicaciones en medicina regenerativa y que podría extenderse a otros sistemas estructuralmente relacionados. (AU)

In the present work, the preparation of a biomaterial from a synthetic terpolymer (TerP) and a natural polymer, physically crosslinked, is shown. In order to evaluate the new material for bone tissue regeneration, physicochemical and biological characterizations were performed. The membranes were obtained by solvent casting and characterized using FTIR spectroscopy, swelling tests, contact angle measurements, and scanning electron microscopy (SEM). It was found that the compatibility between the polymers is stable at physiological pH and the incorporation of a higher amount of TerP into the matrix increases hydrophobicity and porosity.Furthermore, considering the intended application of these materials, studies of biocompatibility and cytotoxicity were conducted with Bone Marrow Progenitor Cells (BMPCs) and RAW264.7 cells, respectively. Cell proliferation, NO production and release into the culture medium for 24 and 48 hours, and proinflammatory cytokine expression of IL-1ß and TNF-α from cells grown on the biomaterials while varying the amount of the synthetic polymer were evaluated. Greater cell proliferation and lower NO production were found on matrices containing a lower proportion of TerP, in addition to better biocompatibility. The results of this study demonstrate that the obtained terpolymer and its combination with a natural polymer is a highly interesting strategy for biomaterial preparation with potential applications in regenerative medicine. This approach could be extended to other structurally related systems. (AU)

Comparison of primary human gingival fibroblasts from an older and a young donor on the evaluation of cytotoxicity of denture adhesives

Abstract Denture adhesives (DA) improve the retention and stability of ill-fitting dentures, especially for older adults. These materials should be biocompatible, i.e., they cannot cause undesired biological responses and be non-cytotoxic to oral tissues. However, in vitro testing of DA biocompatibility employing primary cell culture may possibly be affected by other factors, such as the donor age. Objective To compare the cytotoxicity of three different denture adhesives when assessed in primary gingival fibroblasts from a young donor or from an older donor, as well as the release of the basic fibroblast growth factor (bFGF), and the inflammatory response marker interleukin-6 (IL-6). Material and Methods Gingival fibroblasts isolated from a 30- and a 62-year-old donor were assayed for proliferation (1-7 days) and sensitivity to latex (positive control). Fibroblasts were indirectly exposed to Corega Ultra (cream), Corega powder and Fixodent Original for a 24 h period and assayed by XTT and Crystal Violet tests. The release of IL-6 and bFGF by exposed cells was determined by ELISA. Results While cells from the young donor presented higher cell growth after 7 days, the sensitivity to increasing concentrations of latex extracts was very similar between young and older cells. Both XTT and CVDE detected no difference between the DA and the control group. All materials induced higher levels of IL-6 and bFGF compared to control. Cells from the older donor exposed to Corega Ultra released lower levels of cytokine and growth factor. Conclusions All materials were considered non-cytotoxic, but affected cytokine and growth factor release. The biological differences found between fibroblasts from both donors could be due to individual or age-related factors. The authors suggest the use of cells from older donors on studies of dental products aimed at older patients, to better simulate their physiological response.

Halotolerance, ligninase production and herbicide degradation ability of basidiomycetes strains

Fungi have been recently recognized as organisms able to grow in presence of high salt concentration with halophilic and halotolerance properties and their ligninolytic enzyme complex have an unspecific action enabling their use to degradation of a number of xenobiotic compounds. In this work, both the effect of salt and polyols on growth of the basidiomycetes strains, on their ability to produce ligninolytic enzyme and diuron degradation were evaluated. Results showed that the presence of NaCl in the culture medium affected fungal specimens in different ways. Seven out of ten tested strains had growth inhibited by salt while Dacryopinax elegans SXS323, Polyporus sp MCA128 and Datronia stereoides MCA167 fungi exhibited higher biomass production in medium containing 0.5 and 0.6 mol.L-1 of NaCl, suggesting to be halotolerant. Polyols such as glycerol and mannitol added into the culture media improved the biomass and ligninases production by D. elegans but the fungus did not reveal consumption of these polyols from media. This fungus degraded diuron in medium control, in presence of NaCl as well as polyols, produced MnP, LiP and laccase.

Avaliação da biocompatibilidade do compósito: biocerâmica/ácido poli (lático-co-glicólico) em fibroblastos e macrófagos e da resposta pulpar após capeamento direto / The cell biocompatibility of a bioceramic/poly (lactic-co-glycolic acid) composite and its pulp response in vivo for pulp capping application

Biocerâmicas associadas a polímeros para capeamento pulpar estão sendo investigadas pela capacidade de induzir a formação de tecido mineralizado. Esses materiais são usados na ortopedia e implantodontia com resultados clínicos eficientes. Contudo, pouco se sabe sobre seu efeito sobre a polpa dental e seus componentes celulares. O objetivo deste estudo foi avaliar a biocompatibilidade do compósito: biocerâmica de B-tricálcio fosfato/hidroxiapatita (BC) e co-polímero ácido poli (lático-co-glicólico) (PLGA) (BC/PLGA), em cultura de fibroblastos da polpa dental humana (FP5) e de macrófagos peritoneais (MP), e avaliar a resposta pulpar após capeamento direto após 30 e 60 dias...

Evaluación de la histotoxicidad del 2-octyl-cyanoacrilato en el cerebro del conejo / Histotoxicity evaluation of 2-octyl-cyanoacrylate on the rabbit's brain

The aim of the present study was to evaluate the effect of the 2-octyl-cyanoacrylate, on a rabbit's brain. The study was undertaken to investigate the histological behavior of the brain with this synthetic tissue adhesive. We evaluated a total of 12 rabbits, wich were randomized into 2 groups of 6 rabbits each. Following fronto-temporo-parietal craniectomy, 1 cm of the cranium was removed and the dura mater was 0,5 cm sectioned. In the control group, dura mater was sutured with 6-0 polypropylene interrupted sutures. In the study group, the brains were covered by using 2-octyl-cyanoacrylate (high viscosity), before closurewith 6-0 polypropylene suture. Rabbits were sacrificed on day 7 following operation. Integrity of the sutures, existence of abscess, wound infection and adhesion formation were recorded. The heads were removed including the site of operation and then, the specimens were sent for histological examination. Mean weights of each study group increased. The body temperatures of the animals were normal in the two groups. The histopathological evaluation of the brains treated with the synthetic glue revealed 50 per cent of inflammatory response with focal necrosis in the cortex. Only one rabbit had a normal brain. Results under experimental conditions, indicate that this new substance, 2-octyl-cyanoacrylate, can not be considered as safe supportive material for intradural procedures directly involving the brain tissue.

Biocompatibility test of polyhydroxybutyrate on human cell line

The human fibroblast MRC-5 cells incubated with PHB granules (TM) added at a final concentration of 4 mg/ml showed a time-course pattern of survival. The percentages of dead cells obtained were at the rate of 3.8% after 7 days, respectively. When the MRC-5 cells grown in different material, using the test concentration of 4 mg/ml PCM, they were found to show a similar time-course increasing pattern of death as that obtained with PHB. However, the death was noted in the cells incubated for 7 days, the death rates obtained was 40.54% respectively.

Controle de qualidade de produtos médico-hospitalares: I. Característica de biocompatibilidade em materiais poliméricos / Quality control of medical and hospital products: I. Biocompatibility characteristics of polymeric materials

Alguns correlatos, principalmente dispositivos para uso médico-hospitalar, näo protéticos, produzidos e/ou comercializados no Brasil foram submetidos à análise, visando averiguar algumas características relacionadas com a biocompatibilidade. Foram amostrados 11 tipos de correlatos (cateter intravenoso, equipo de administraçäo parenteral, escalpo, seringa hipodérmica, torneira três vias, bandeja de circulaçäo extracorpórea, oxigenador sanguíneo, reservatório de cardiotomia, bainha urinária e preservativo), perfazendo 72 lotes. As determinaçöes analíticas para avaliaçäo das amostras foram: toxicidade sistêmica aguda em camundongos, esterilidade, endotoxinas, toxicidade intramuscular aguda e citotoxicidade em cultura celular. Com relaçäo às características dos produtos, 12 lotes dentre 72 acusaram citotoxicidade, seja pelo teste "in vivo" ou "in vitro"