Departamento de Genética Humana
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Browsing Departamento de Genética Humana by advisor "Bettencourt, Ana"
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- Biological Effects of Acrylic Engineered Particulate-SystemsPublication . Graça, Diogo; Bettencourt, Ana; Silva, Maria João[ENG] Polymeric particulate-systems are of great relevance due to their possible biomedical applications, among them as carriers for the nano- or microencapsulation of drugs. However, due to their unique specific properties, namely small size range, toxicity issues must be discarded before allowing its use on health-related applications. Several polymers, as poly(methylmethacrylate) (PMMA), have proved to be suitable for the preparation of particulate-systems. However, a major drawback of its use refers to incomplete drug release from particles matrix. Recent strategies to improve PMMA release properties mention the inclusion of other acrylic polymers as Eudragit (EUD) on particles formulation. Though PMMA and EUD are accepted by the FDA as biocompatible, their safety on particle composition lacks sufficient toxicological data. The main objective of this thesis was to evaluate the biological effects of engineered acrylic particulate-systems. Preparation, physicochemical characterization and in vitro toxicity evaluation were assessed on PMMA and PMMA-EUD (50:50) particles. The emulsification-solvent evaporation methodology allowed the preparation of particles with spherical and smooth surfaces within the micrometer range (±500 nm), opposing surface charges and different levels of hydrophobicity. It was observed that particles physicochemical properties (size and charge) were influenced by biological media composition, such as serum concentration, ionic strength or pH. In what concerns to the in vitro toxicological studies, particle cellular uptake was observed on different cell lines (macrophages, osteoblasts and fibroblasts). Cytotoxicity effects were only found after 72 h of cells exposure to the particles, while no oxidative damage was observed neither on osteoblasts nor fibroblasts. Also, no genotoxicity was found in fibroblast using the comet assay to assess DNA damage. This observation should be further confirmed with other validated genotoxicity assays (e.g. Micronucleus Assay). The present study suggests that the evaluated acrylic particles are biocompatible, showing promising biological properties for potential use as carriers in drug-delivery systems.
- Safety Assessment of Polymeric Nanoparticle Carriers for Drug Delivery in Human OsteoblastsPublication . Dias, Kamila Kappke; Silva, Maria João; Bettencourt, AnaNanoparticles (NPs) applied to pharmaceutics constitute an innovative approach to improve drug release profiles on targeted sites. The assessment of their biocompatibility and safety for human health plays also a major role in the development process. The objective of this work was to characterize the cellular interactions and potential toxicity of polymeric nanoparticles, in human osteoblasts. Poly(methyl methacrylate) (PMMA) and Eudragit® RL 100 (Eud) were used to produce PMMA and PMMA-Eud (50:50) NPs (average size range of 500 nm) by single-emulsion with solvent evaporation methodology. Their physicochemical properties (size distribution, surface charge, morphology and aggregation/agglomeration states) were analysed. Their safety evaluation was conducted in “normal” and differentiated MG63 cells. Cell uptake, cyto- and genotoxicity were characterized using several endpoints: cell viability (MTT assay), oxidative stress production (H2DCFDA assay), DNA and chromosome damage (Comet and Micronucleus assays). The results confirmed the successful cellular uptake of PMMA and PMMA-Eud. Both NPs were neither cytotoxic nor able to produce oxidative stress in differentiated cells, although a moderated toxicity was detected in undifferentiated cells. As to the genotoxic potential, both NPs induced primary DNA damage (comet assay) in osteoblasts, especially in short-term exposure. Noteworthy, none of the NPs caused chromosome alterations, indicating that the DNA lesions were not converted into permanent genetic damage. However, an increased cell proliferative capacity was noted for PMMA that needs confirmation. In conclusion, PMMA and PMMA-Eud are promising nanocarriers in drug delivery systems. Their in vitro safety assessment in osteoblasts indicated that both NPs are biocompatible but display a weak genotoxicity that needs further investigation, e.g., using other endpoints or in vivo models. The utilization of cells under different specialization status improved data reliability. Moreover, understanding how physicochemical features relate to toxicity will support the design of safer formulations for biomedical purposes as envisaged by the safer-by-design concept.