RESUMO
Generation 4 of polyamidoamine dendrimer (G4-PAMAM) has several biological effects due to its tridimensional globular structure, repetitive branched amides, tertiary amines, and amino-terminal subunit groups liked to a common core. G4-PAMAM is cytotoxic due to its positive charges. However, its cytotoxicity could increase in cancer cells due to the excessive intracellular negative charges in these cells. Furthermore, this work reports G4-PAMAM chemical structural characterization using UHPLC-QTOF-MS/MS (LC-MS) by electrospray ionization to measure its population according to its positive charges. Additionally, the antiproliferative effects and intracellular localization were explored in the HMC-1 and K-562 cell lines by confocal microscopy. The LC-MS results show that G4-PAMAM generated multivalent mass spectrum values, and its protonated terminal amino groups produced numerous positive charges, which allowed us to determine its exact mass despite having a high molecular weight. Additionally, G4-PAMAM showed antiproliferative activity in the HMC-1 tumor cell line after 24 h (IC50 = 16.97 µM), 48 h (IC50 = 7.02 µM) and 72 h (IC50 = 5.98 µM) and in the K-562 cell line after 24 h (IC50 = 15.14 µM), 48 h (IC50 = 14.18 µM) and 72 h (IC50 = 9.91 µM). Finally, our results showed that the G4-PAMAM dendrimers were located in the cytoplasm and nucleus in both tumor cell lines studied.
Assuntos
Dendrímeros/farmacologia , Leucemia/tratamento farmacológico , Leucemia/metabolismo , Nylons/farmacologia , Antineoplásicos/análise , Antineoplásicos/farmacocinética , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Cromatografia Líquida , Dendrímeros/análise , Dendrímeros/farmacocinética , Ensaios de Seleção de Medicamentos Antitumorais/métodos , Humanos , Concentração Inibidora 50 , Espaço Intracelular/efeitos dos fármacos , Espaço Intracelular/metabolismo , Células K562 , Leucemia/patologia , Nylons/análise , Nylons/farmacocinética , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem , Distribuição TecidualRESUMO
Understanding the molecular features responsible for the plasma kinetics of surface-modified polyamido amine (PAMAM) dendrimers is critical to explore novel biomedical applications for these nanomaterials. In this report, polyethylene glycol (PEG) and folic acid (FA) were employed to obtain partially-substituted PAMAM dendrimers as model biocompatible nanomaterials with different size, charge and surface functionality. Cytotoxicity assays on HEK cells at 1-500⯵M concentration confirmed that PEG and FA incorporation increased the cell viability of PAMAM-based nanomaterials. Measurements of plasma kinetics in vivo revealed that PEG-PAMAM has an extended circulation time in mice blood (71.7â¯min) over native PAMAM (53.3â¯min) and FA-PAMAM (41.8â¯min). Molecular dynamics simulations revealed a direct relationship between circulation time and dendrimer size, thus providing valuable evidence to increase understanding about the modulation of functional properties of PAMAM-based systems through surface modification, and to guide future efforts on the rational design of novel biomedical nanomaterials.
Assuntos
Apoptose , Dendrímeros/farmacologia , Portadores de Fármacos/química , Plasma/metabolismo , Animais , Proliferação de Células , Dendrímeros/farmacocinética , Ácido Fólico/química , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Simulação de Dinâmica MolecularRESUMO
Secondary neuronal death is a serious stroke complication. This process is facilitated by the conversion of glial cells to the reactive pro-inflammatory phenotype that induces neurodegeneration. Therefore, regulation of glial activation is a compelling strategy to reduce brain damage after stroke. However, drugs have difficulties to access the CNS, and to specifically target glial cells. In the present work, we explored the use core-shell polyamidoamine tecto-dendrimer (G5G2.5 PAMAM) and studied its ability to target distinct populations of stroke-activated glial cells. We found that G5G2.5 tecto-dendrimer is actively engulfed by primary glial cells in a time- and dose-dependent manner showing high cellular selectivity and lysosomal localization. In addition, oxygen-glucose deprivation or lipopolysaccharides exposure in vitro and brain ischemia in vivo increase glial G5G2.5 uptake; not being incorporated by neurons or other cell types. We conclude that G5G2.5 tecto-dendrimer is a highly suitable carrier for targeted drug delivery to reactive glial cells in vitro and in vivo after brain ischemia.
Assuntos
Isquemia Encefálica/tratamento farmacológico , Dendrímeros/farmacocinética , Neuroglia/metabolismo , Acidente Vascular Cerebral/tratamento farmacológico , Animais , Isquemia Encefálica/complicações , Dendrímeros/química , Sistemas de Liberação de Medicamentos/métodos , Masculino , Cultura Primária de Células , Ratos Wistar , Acidente Vascular Cerebral/complicaçõesRESUMO
The purpose of this study was to evaluate the effect of generation and surface PEGylation of degradable polyester-based dendrimers nanocarriers on their interactions with an in vitro model of the pulmonary epithelium as well as to assess the ability to formulate such carriers in propellant-based, portable oral-inhalation devices to determine their potential for local and systemic delivery of drugs to and through the lungs. Hydroxyl (-OH) terminated polyester dendrimers of generation 3 and 4 (G3, and G4) were synthesized using a divergent approach. G4 was surface-modified with PEG (1,000Da). All dendrimers and their building blocks were determined to be highly compatible with the model pulmonary epithelium, with toxicity profiles much more favorable than non-degradable polyamidoamine dendrimers (PAMAM). The transport of the species from the apical to basolateral side across polarized Calu-3 monolayers showed to be generation and surface-chemistry (PEGylation) dependent. The extent of the transport is modulated by their interaction with the polarized epithelium and their transient opening of the tight junctions. G3 was the one most efficiently internalized by the epithelium, and had a small impact on the integrity of the monolayer. On the other hand, the PEGylated G4 was the one least internalized by the polarized epithelium, and at the same time had a more pronounced transient impact on the cellular junctions, resulting in more efficient transport across the cell monolayer. PEGylation of the dendrimer surface played other roles as well. PEGylation modulated the degradation profile of the dendrimer, slowing the process in a step-wise fashion - first the PEG layer is shed and then the dendrimer starts degrading. PEGylation also helped increase the solvation of the nanocarriers by the hydrofluoroalkane propellant used in pressurized metered-dose inhalers, resulting in formulations with excellent dispersibility and aerosol quality (deep lung deposition of 88.5%), despite their very small geometric diameter. The combined in vitro and formulation performance results shown here demonstrated that degradable, modified polyester dendrimers may serve as a valuable platform that can be tailored to target the lung tissue for treating local diseases, or the circulation, using the lungs as pathway to the bloodstream.
Assuntos
Dendrímeros/farmacocinética , Composição de Medicamentos/métodos , Epitélio/metabolismo , Pulmão/metabolismo , Inaladores Dosimetrados , Poliésteres/farmacocinética , Proteínas de Artrópodes , Plásticos Biodegradáveis/química , Plásticos Biodegradáveis/farmacocinética , Plásticos Biodegradáveis/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Dendrímeros/química , Dendrímeros/farmacologia , Humanos , Poliésteres/química , Poliésteres/farmacologia , Polietilenoglicóis/química , Polietilenoglicóis/farmacocinética , Pressão , Venenos de AranhaRESUMO
BACKGROUND: Gene silencing using small interfering RNA (siRNA) is a promising new therapeutic approach for glioblastoma. The endocytic uptake and delivery of siRNA to intracellular compartments could be enhanced by complexation with polyamidoamine dendrimers. In the present work, the uptake mechanisms and intracellular traffic of siRNA/generation 7 dendrimer complexes (siRNA dendriplexes) were screened in T98G glioblastoma and J774 macrophages. METHODS: The effect of a set of chemical inhibitors of endocytosis on the uptake and silencing capacity of dendriplexes was determined by flow cytometry. Colocalization of fluorescent dendriplexes with endocytic markers and occurrence of intracellular dissociation were assessed by confocal laser scanning microscopy. RESULTS: Uptake of siRNA dendriplexes by T98G cells was reduced by methyl-ß-cyclodextrin, and genistein, and cytochalasine D, silencing activity was reduced by genistein; dendriplexes colocalized with cholera toxin subunit B. Therefore, caveolin-dependent endocytosis was involved both in the uptake and silencing activity of siRNA dendriplexes. On the other hand, uptake of siRNA dendriplexes by J774 cells was reduced by methyl-ß-cyclodextrin, genistein, chlorpromazine, chloroquine, cytochalasine D, and nocodazole, the silencing activity was not affected by chlorpromazine, genistein or chloroquine, and dendriplexes colocalized with transferrin and cholera toxin subunit B. Thus, both clathrin-dependent and caveolin-dependent endocytosis mediated the uptake and silencing activity of the siRNA dendriplexes. SiRNA dendriplexes were internalized at higher rates by T98G but induced lower silencing than in J774 cells. SiRNA dendriplexes showed relatively slow dissociation kinetics, and their escape towards the cytosol was not mediated by acidification independently of the uptake pathway. CONCLUSION: The extent of cellular uptake of siRNA dendriplexes was inversely related to their silencing activity. The higher silencing activity of siRNA dendriplexes in J774 cells could be ascribed to the contribution of clathrin-dependent and caveolin-dependent endocytosis vs only caveolin-dependent endocytosis in T98G cells.
Assuntos
Dendrímeros/farmacocinética , Endocitose/efeitos dos fármacos , Inativação Gênica , Glioblastoma/metabolismo , Macrófagos/metabolismo , RNA Interferente Pequeno/farmacocinética , Análise de Variância , Animais , Biomarcadores/metabolismo , Caveolinas/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Clatrina/metabolismo , Dendrímeros/administração & dosagem , Endossomos/metabolismo , Glioblastoma/tratamento farmacológico , Glioblastoma/genética , Humanos , Espaço Intracelular/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Camundongos , RNA Interferente Pequeno/administração & dosagemRESUMO
Study of fluorophore and technetium labeling of poly(amido)-amine (PAMAM) generation 4 (G4) dendrimer and its evaluation as potential molecular imaging agent in both normal and melanoma-bearing mice, are described. Dendrimers were first conjugated with FITC (fluorescein isothiocyanate). Dendrimer-FITC was then incubated with the intermediate [(99m)Tc(CO)(3)(H(2)O)(3)](+) and purified by gel filtration. Biodistribution and scintigraphy images were performed administrating (99m)Tc(CO)(3)-dendrimer-FITC to normal mice (NM) or melanoma-bearing mice (MBM). Cryostat tissue sections from MBM mice were analyzed by confocal microscopy. Radiolabeling yield of dendrimer was approx. 90%. The (99m)Tc(CO)(3)-dendrimer-FITC complex was stable for at least 24h. Biodistribution studies in NM showed blood clearance with hepatic and renal depuration. MBM showed a similar pattern of biodistribution with high tumor uptake that allowed tumor imaging. Confocal microscopy analysis showed cytoplasmic distribution of (99m)Tc(CO)(3)-dendrimer-FITC.