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1.
Obes Facts ; 14(4): 415-424, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34344002

RESUMO

INTRODUCTION: Metabolic adaptations to maximal physical exercise in people with obesity (PwO) are scarcely described. This cross-sectional study evaluates the metabolic response to exercise via the respiratory exchange ratio (RER) in PwO and different degrees of glycemic control. METHODS: Eighty-five PwO (body mass index 46.0 [39.0-54.0] kg/m2), that is, 32 normoglycemic (Ob-N), 25 prediabetic (Ob-preDM), and 28 diabetic (Ob-T2DM) subjects and 18 healthy subjects performed an incremental, maximal cardiopulmonary exercise test. The RER was measured at rest (RERrest) and at peak exercise (RERpeak). RESULTS: RERpeak was significantly higher in healthy subjects than that in PwO. Among those, RERpeak was significantly higher in Ob-N than that in Ob-preDM and Ob-T2DM (1.20 [1.15-1.27] vs. 1.18 [1.10-1.22] p = 0.04 and vs. 1.14 [1.10-1.18] p < 0.001, respectively). Accordingly, ΔRER (RERpeak-RERrest) was lower in Ob-preDM and Ob-T2DM than that in Ob-N (0.32 [0.26-0.39] p = 0.04 and 0.29 [0.24-0.36] p < 0.001 vs. 0.38 [0.32-0.43], respectively), while no significant difference was found in ΔRER between Ob-preDM and Ob-T2DM and not even between Ob-N and healthy subjects. Moreover, ΔRER in PwO correlated with glucose area under curve (p = 0.002). CONCLUSIONS: PwO demonstrate restricted metabolic response during maximal exercise. Particularly, those with prediabetes already show metabolic inflexibility during exercise, similarly to those with type 2 diabetes. These findings also suggest a potential role of cardiopulmonary exercise testing in detecting early metabolic alterations in PwO.

2.
Nutrients ; 13(8)2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34444930

RESUMO

Fewer studies compared the improvement of plasma lipid levels after different types of surgery, in particular compared to one-anastomosis gastric bypass (OAGB). The aim of our study was to investigate how laparoscopic sleeve gastrectomy (LSG) and OAGB impact on weight loss and lipid profile 18 months after surgery, in patients with severe obesity. Forty-six patients treated with OAGB were matched to eighty-eight patients submitted to LSG. Weight loss after OAGB (33.2%) was more evident than after LSG (29.6%) (p = 0.024). The difference in the prevalence of dyslipidemia showed a statistically significant reduction only after OAGB (61% versus 22%, p < 0.001). After adjustment for delta body mass index (BMI), age and sex, we demonstrated a statistically significant decrease of the differences between the changes before and after (delta Δ) the two surgery procedures: Δ total cholesterol values (p < 0.001), Δ low density lipoprotein-cholesterol values (p < 0.001) and Δ triglycerides values (p = 0.007). Patients with severe obesity undergoing to OAGB presented a better improvement of lipid plasma values than LSG patients. The reduction of lipid plasma levels was independent of the significant decrease of BMI after surgery, of age and of sex.


Assuntos
Gastrectomia/métodos , Derivação Gástrica/métodos , Lipídeos/sangue , Obesidade Mórbida/sangue , Adolescente , Adulto , Idoso , Antropometria , Índice de Massa Corporal , Colesterol/sangue , LDL-Colesterol/sangue , Feminino , Humanos , Laparoscopia , Masculino , Pessoa de Meia-Idade , Obesidade Mórbida/cirurgia , Período Pós-Operatório , Resultado do Tratamento , Triglicerídeos/sangue , Perda de Peso , Adulto Jovem
4.
Int J Mol Sci ; 21(21)2020 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-33114687

RESUMO

Multiple symmetric lipomatosis (MSL) is a rare disorder characterized by overgrowing lipomatous tissue (LT) in the subcutaneous adipose tissue (SAT). What LT is and how it expands are not completely understood; previous data suggested that it could derive from brown AT precursors. In six MSL type I patients, we compared LT morphology by histological and immunohistochemistry (IHC) analysis, gene expression, by qPCR, kinase activity, by Western Blot and in vitro assay to paired-control SAT using AT from patients with pheochromocytoma as a human browning reference. In the stromal vascular fraction (SVF), we quantified adipose stem cells (ASCs) by flow cytometry, the proliferation rate, white and beige adipogenic potential and clonogenicity and adipogenicity by a limiting dilution assay. LT displayed white AT morphology and expression pattern and did not show increased levels of the brown-specific marker UCP1. In LT, we evidenced AKT, CK2 and ERK1/2 hyperactivation. LT-SVF contained increased ASCs, proliferated faster, sprouted clones and differentiated into adipocytes better than the control, displaying enhanced white adipogenic potential but not increased browning compared to SAT. In conclusion, LT is a white AT depot expanding by hyperplasia through increased stemness and enhanced white adipogenesis upregulating AKT, CK2 and ERK1/2, which could represent new targets to counteract MSL.


Assuntos
Tecido Adiposo Branco/metabolismo , Neoplasias das Glândulas Suprarrenais/metabolismo , Lipomatose Simétrica Múltipla/metabolismo , Feocromocitoma/metabolismo , Regulação para Cima , Neoplasias das Glândulas Suprarrenais/genética , Idoso , Estudos de Casos e Controles , Caseína Quinase II/genética , Caseína Quinase II/metabolismo , Diferenciação Celular , Proliferação de Células , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Feminino , Perfilação da Expressão Gênica , Humanos , Lipomatose Simétrica Múltipla/genética , Masculino , Pessoa de Meia-Idade , Feocromocitoma/genética , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Células-Tronco/citologia , Células-Tronco/metabolismo
5.
Artigo em Inglês | MEDLINE | ID: mdl-31440209

RESUMO

Determinants of resting energy expenditure (REE) in humans are still under investigation, especially the association with insulin resistance. Brown adipose tissue (AT) regulates energy expenditure through the activity of the uncoupling protein 1 (UCP1). White AT browning is the process by which some adipocytes within AT depots acquire properties of brown adipocytes ("brite" adipocytes) and it correlates with metabolic improvement. We analyzed determinants of REE in patients with obesity and assessed UCP1 expression as a "brite" marker in abdominal subcutaneous AT (SAT) and visceral omental AT (VAT). Clinical data, REE, free fat mass (FFM), and fat mass (FM) were determined in 209 patients with obesity. UCP1, PPARG coactivator 1 alpha (PPARGC1A), transcription factor A, mitochondrial (TFAM), T-box transcription factor 1 (TBX1), and solute carrier family 27 member 1 (SLC27A1) expression was assayed in SAT and VAT samples, obtained during sleeve gastrectomy from 62 patients with obesity. REE and body composition data were also available for a subgroup of 35 of whom. In 209 patients with obesity a multiple regression model was computed with REE as the dependent variable and sex, waist, FFM, FM, homeostasis model assessment-insulin resistance (HOMA), interleukin-6 and High Density Lipoprotein-cholesterol as the independent variables. Only FFM, FM and HOMA were independently correlated with REE (r = 0.787, AdjRsqr = 0.602). In each patient VAT displayed a higher UCP1, PPARGC1A, TFAM, TBX1, and SLC27A1 expression than SAT and UCP1 expression in VAT (UCP1-VAT) correlated with Body Mass Index (BMI) (r = 0.287, p < 0.05). Introducing UCP1-VAT in the multivariate model, we showed that FFM, HOMA, interleukin-6, High Density Lipoprotein-cholesterol, and UCP1-VAT were independent factors correlated with REE (r = 0.736, AdjRsqr = 0.612). We confirmed that REE correlates with FFM, FM and HOMA in a large cohort of patients. Our results clearly showed that UCP1-VAT expression was significantly increased in severe human obesity (BMI > 50 kg/m2) and that it behaved as an independent predictor of REE. Lastly, we suggest that an increased REE and browning in metabolically complicated severe obesity could represent an effort to counteract further weight gain.

6.
Sci Rep ; 9(1): 11333, 2019 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-31383894

RESUMO

Although obesity represents a risk factor for the development of type 2 diabetes mellitus (T2DM), the link between these pathological conditions is not so clear. The manner in which the different elements of adipose tissue (AT) interplay in order to grow has been suggested to have a role in the genesis of metabolic complications, but this has not yet been fully addressed in humans. Through IHC, transmission electron microscopy, cytometry, and in vitro cultures, we described the morphological and functional changes of subcutaneous and visceral AT (SAT and VAT) in normoglycemic, prediabetic and T2DM patients with obesity compared to lean subjects. In both SAT and VAT we measured a hypertrophic and hyperplastic expansion, causing similar vascular rarefaction in obese patients with different degrees of metabolic complications. Capillaries display dysfunctional basement membrane thickening only in T2DM patients evidencing VAT as a new target of T2DM microangiopathy. The largest increase in adipocyte size and decrease in adipose stem cell number and adipogenic potential occur both in T2DM and in prediabetes. We showed that SAT and VAT remodeling with stemness deficit is associated with early glucose metabolism impairment suggesting the benefit of an AT-target therapy controlling hypertrophy and hyperplasia already in prediabetic obese patients.


Assuntos
Gordura Abdominal/patologia , Diabetes Mellitus Tipo 2/patologia , Glucose/metabolismo , Obesidade/patologia , Gordura Subcutânea/patologia , Gordura Abdominal/metabolismo , Adulto , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade/complicações , Obesidade/metabolismo , Gordura Subcutânea/metabolismo
7.
Obes Surg ; 28(8): 2481-2486, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29532316

RESUMO

OBJECTIVES: Resting energy expenditure (REE) declines more than what is expected according to body composition changes after caloric restriction. This metabolic adaptation is considered one of the factors favoring weight regain. The aim of this study is to evaluate the changes of REE and calculate the degree of metabolic adaptation occurring after laparoscopic sleeve gastrectomy (LSG). METHODS: REE (by indirect calorimetry) and body composition (fat-free mass or FFM, fat mass or FM by bioelectrical impedance analysis) were determined before and after 12 months in 154 patients with obesity treated with laparoscopic sleeve gastrectomy (LSG). RESULTS: Weight loss was 29.8 ± 10.6%, with corresponding relative reductions in FM (44.5 ± 22.8%), FFM (13.7 ± 9.9%), and REE (27.3 ± 12.9%). A predictive equation for REE was computed by using the baseline FFM and FM values to account for body composition changes. A predicted post-weight loss REE was calculated by using this equation and entering post-weight loss body composition values. Observed post-surgery REE was significantly lower than predicted one (1410 ± 312 vs 1611 ± 340 kcal/day, P < 0.001) and metabolic adaptation, calculated as the difference between observed and predicted post-weight loss REE, was - 199 ± 238 kcal/day. The post-surgery level of metabolic adaptation was inversely related to postoperative percent weight loss (r = - 0.170; P < 0.05) and FM loss (r = - 0.245; P < 0.01). CONCLUSIONS: A significant reduction of resting energy expenditure and a significant degree of metabolic adaptation both occur after sleeve gastrectomy. A greater metabolic adaptation could be partly responsible for a lower weight loss after surgery.


Assuntos
Adaptação Fisiológica , Cirurgia Bariátrica/estatística & dados numéricos , Metabolismo Energético , Gastrectomia/estatística & dados numéricos , Obesidade Mórbida/cirurgia , Adulto , Composição Corporal , Restrição Calórica , Calorimetria Indireta , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade/cirurgia , Obesidade Mórbida/metabolismo , Descanso , Perda de Peso
8.
Int J Environ Res Public Health ; 11(9): 8867-90, 2014 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-25170680

RESUMO

Silica (SiO2) nanoparticles (NPs) have found extensive applications in industrial manufacturing, biomedical and biotechnological fields. Therefore, the increasing exposure to such ultrafine particles requires studies to characterize their potential cytotoxic effects in order to provide exhaustive information to assess the impact of nanomaterials on human health. The understanding of the biological processes involved in the development and maintenance of a variety of pathologies is improved by genome-wide approaches, and in this context, gene set analysis has emerged as a fundamental tool for the interpretation of the results. In this work we show how the use of a combination of gene-by-gene and gene set analyses can enhance the interpretation of results of in vitro treatment of A549 cells with Ludox® colloidal amorphous silica nanoparticles. By gene-by-gene and gene set analyses, we evidenced a specific cell response in relation to NPs size and elapsed time after treatment, with the smaller NPs (SM30) having higher impact on inflammatory and apoptosis processes than the bigger ones. Apoptotic process appeared to be activated by the up-regulation of the initiator genes TNFa and IL1b and by ATM. Moreover, our analyses evidenced that cell treatment with LudoxÒ silica nanoparticles activated the matrix metalloproteinase genes MMP1, MMP10 and MMP9. The information derived from this study can be informative about the cytotoxicity of Ludox® and other similar colloidal amorphous silica NPs prepared by solution processes.


Assuntos
Nanopartículas/toxicidade , Dióxido de Silício/toxicidade , Transcrição Genética/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Perfilação da Expressão Gênica , Humanos , Análise de Sequência com Séries de Oligonucleotídeos , Tamanho da Partícula , Reação em Cadeia da Polimerase em Tempo Real
9.
Cell Mol Life Sci ; 71(19): 3659-83, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24699705

RESUMO

Influenza viruses are major human pathogens responsible for respiratory diseases affecting millions of people worldwide and characterized by high morbidity and significant mortality. Influenza infections can be controlled by vaccination and antiviral drugs. However, vaccines need annual updating and give limited protection. Only two classes of drugs are currently approved for the treatment of influenza: M2 ion channel blockers and neuraminidase inhibitors. However, they are often associated with limited efficacy and adverse side effects. In addition, the currently available drugs suffer from rapid and extensive emergence of drug resistance. All this highlights the urgent need for developing new antiviral strategies with novel mechanisms of action and with reduced drug resistance potential. Several new classes of antiviral agents targeting viral replication mechanisms or cellular proteins/processes are under development. This review gives an overview of novel strategies targeting the virus and/or the host cell for counteracting influenza virus infection.


Assuntos
Antivirais/uso terapêutico , Influenza Humana/tratamento farmacológico , Anticorpos Neutralizantes/imunologia , Antivirais/farmacologia , RNA Polimerases Dirigidas por DNA/antagonistas & inibidores , RNA Polimerases Dirigidas por DNA/metabolismo , Hemaglutininas/imunologia , Hemaglutininas/metabolismo , Humanos , Influenza Humana/virologia , Neuraminidase/antagonistas & inibidores , Neuraminidase/metabolismo , Orthomyxoviridae/efeitos dos fármacos , Orthomyxoviridae/metabolismo , Proteínas do Core Viral/antagonistas & inibidores , Proteínas do Core Viral/metabolismo , Proteínas da Matriz Viral/antagonistas & inibidores , Proteínas da Matriz Viral/metabolismo , Internalização do Vírus/efeitos dos fármacos , Replicação Viral/efeitos dos fármacos
10.
J Med Chem ; 57(4): 1403-15, 2014 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-24456407

RESUMO

Cationic antimicrobial peptides (CAMPs) and photodynamic therapy (PDT) are attractive tools to combat infectious diseases and to stem further development of antibiotic resistance. In an attempt to increase the efficiency of bacteria inactivation, we conjugated a PDT photosensitizer, cationic or neutral porphyrin, to a CAMP, buforin or magainin. The neutral and hydrophobic porphyrin, which is not photoactive per se against Gram-negative bacteria, efficiently photoinactivated Escherichia coli after conjugation to either buforin or magainin. Conjugation to magainin resulted in the considerable strengthening of the cationic and hydrophilic porphyrin's interaction with the bacterial cells, as shown by the higher bacteria photoinactivation activity retained after washing the bacterial suspension. The porphyrin-peptide conjugates also exhibited strong interaction capability as well as photoactivity toward eukaryotic cells, namely, human fibroblasts. These findings suggest that these CAMPs have the potential to carry drugs and other types of cargo inside mammalian cells similar to cell-penetrating peptides.


Assuntos
Magaininas/química , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/farmacologia , Porfirinas/química , Sequência de Aminoácidos , Dicroísmo Circular , Células Eucarióticas/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Dados de Sequência Molecular , Fotoquimioterapia , Fármacos Fotossensibilizantes/química , Espectrofotometria Ultravioleta
11.
Nanoscale ; 5(13): 6106-16, 2013 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-23728482

RESUMO

PEGylated and non-PEGylated ORMOSIL nanoparticles prepared by microemulsion condensation of vinyltriethoxy-silane (VTES) were investigated in detail for their micro-structure and ability to deliver photoactive agents. With respect to pure silica nanoparticles, organic modification substantially changes the microstructure and the surface properties. This in turn leads to a modulation of both the photophysical properties of embedded photosensitizers and the interaction of the nanoparticles with biological entities such as serum proteins. The flexibility of the synthetic procedure allows the rapid preparation and screening of multifunctional nanosystems for photodynamic therapy (PDT). Selective targeting of model cancer cells was tested by using folate, an integrin specific RGD peptide and anti-EGFR antibodies. Data suggest the interference of the stealth-conferring layer (PEG) with small targeting agents, but not with bulky antibodies. Moreover, we showed that selective photokilling of tumour cells may be limited even in the case of efficient targeting because of intrinsic transport limitations of active cellular uptake mechanisms or suboptimum localization.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Nanopartículas/química , Neoplasias/tratamento farmacológico , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes , Siloxanas , Anticorpos Antineoplásicos/química , Anticorpos Antineoplásicos/farmacologia , Receptores ErbB/antagonistas & inibidores , Células HeLa , Células Endoteliais da Veia Umbilical Humana , Humanos , Neoplasias/metabolismo , Neoplasias/patologia , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Polietilenoglicóis/química , Polietilenoglicóis/farmacologia , Siloxanas/química , Siloxanas/farmacologia
12.
Anal Bioanal Chem ; 404(6-7): 1789-802, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23053168

RESUMO

We analyzed the influence of the kind of cytotoxicity test and its application modality in defining the level of hazard of the in vitro exposures to nanostructures. We assessed the cytotoxicity induced by two different Ludox® silica nanoparticles (NPs), AS30 and SM30, on three human cell lines, CCD-34Lu, A549, and HT-1080. Dynamic light scattering measurements showed particle agglomeration when NPs are diluted in culture medium supplemented with fetal calf serum. We examined the impact of such particle aggregation on the cytotoxicity by exposing the cells to NPs under different treatment modalities: short incubation (2 h) in serum-free medium or long incubation (24-72 h) in serum-containing medium. Under this last modality, NP suspensions tended to form aggregates and were toxic at concentrations five- to tenfold higher than in serum-free medium. The results of cell survival varied considerably when the long-term clonogenic assay was performed to validate the data of the short-term MTS assay. Indeed, the half maximum effective concentrations (EC(50)) in all the three cell lines were four- to fivefold lower when calculated from the data of clonogenic assay than of MTS. Moreover, the mechanisms of NP toxicity were cell-type-specific, showing that CCD-34Lu are prone to the induction of plasma membrane damages and HT-1080 are prone to DNA double-strand break and apoptosis induction. Taken together, our results demonstrate that the choice of testing strategy and treatment conditions plays an important role in assessing the in vitro toxicity of NPs.


Assuntos
Nanopartículas/toxicidade , Dióxido de Silício/toxicidade , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Humanos , Tamanho da Partícula
13.
Nanomedicine (Lond) ; 7(5): 663-77, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22630150

RESUMO

AIMS: In this study we evaluated temoporfin-loaded polyethylene glycol (PEG) Poly-(D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) as a new formulation for potential use in cancer treatment. MATERIALS & METHODS: NPs were characterized for their photophysical properties, temoporfin release, cellular uptake and intracellular localization, and dark and photocytotoxicities of temoporfin by using A549, MCF10A neoT and U937 cell lines. In vivo imaging was performed on athymic nude-Foxn1 mice. RESULTS: Temoporfin was highly aggregated within the NPs and the release of temoporfin monomers was faster from PEGylated PLGA NPs than from non-PEGylated ones. PEGylation significantly reduced the cellular uptake of NPs by the differentiated promonocytic U937 cells, revealing the stealth properties of the delivery system. Dark cytotoxicity of temoporfin delivered by NPs was less than that of free temoporfin in standard solution (Foscan(®), Biolitec AG [Jena, Germany]), whereas phototoxicity was not reduced. Temoporfin delivered to mice by PEGylated PLGA NPs exhibits therapeutically favorable tissue distribution. CONCLUSION: These encouraging results show promise in using PEGylated PLGA NPs for improving the delivery of photosensitizers for photodynamic therapy.


Assuntos
Sistemas de Liberação de Medicamentos , Mesoporfirinas/química , Nanopartículas/química , Fotoquimioterapia , Animais , Linhagem Celular Tumoral , Humanos , Ácido Láctico/química , Camundongos , Camundongos Nus , Nanopartículas/uso terapêutico , Polietilenoglicóis/química , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico
14.
Photochem Photobiol Sci ; 10(11): 1751-9, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21874194

RESUMO

We studied the effects of density and thickness of PEG coating on in vitro cellular uptake, and dark- and photo-toxicity of liposomal formulations (Fospeg) of the photodynamic agent meta-tetrahydroxyphenyl chlorin (m-THPC). The cellular uptake of various Fospeg formulations was determined by flow cytometry in CCD-34Lu human normal fibroblasts and A549 lung cancer cells. Dark and light-induced cytotoxicity was measured by MTS assay after exposure to increasing concentrations of Fospeg only and followed by irradiation with red light. Intracellular localization of m-THPC delivered by Fospeg was determined by fluorescence microscopy. The studies were carried out in comparison with m-THPC delivered by the standard solvent. In the dark all Fospeg formulations were less cytotoxic than m-THPC in standard solvent (ethanol/poly(ethylene glycol 400/water; 20 : 30 : 50 by vol.) and cytotoxicity decreased by increasing PEGylation. m-THPC delivered as Fospeg was internalised by endocytosis and localised mainly in the Golgi apparatus and endoplasmic reticulum. The efficiency of cellular uptake of Fospeg was reduced by 30-40% with respect to m-THPC in standard solution causing a slight reduction of the phototoxicity but without serious impairment of the efficacy of the treatment. Our study suggests that PEGylated liposomes are promising nanocarriers for the delivery of photosensitisers for photodynamic therapy because they reduce dark cytotoxicity while preserving therapeutic efficacy.


Assuntos
Lipossomos/química , Mesoporfirinas/toxicidade , Fármacos Fotossensibilizantes/toxicidade , Polietilenoglicóis/química , Linhagem Celular , Endocitose , Humanos , Luz , Microscopia de Fluorescência
15.
Nanotechnology ; 20(34): 345101, 2009 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-19652275

RESUMO

Nanosized objects made of various materials are gaining increasing attention as promising vehicles for the delivery of therapeutic and diagnostic agents for cancer. Photodynamic therapy (PDT) appears to offer a very attractive opportunity to implement drug delivery systems since no release of the sensitizer is needed to obtain the therapeutic effect and the design of the nanovehicle should be much easier. The aim of our study was to investigate the use of organic-modified silica nanoparticles (NPs) for the delivery of the second-generation photosensitizer meta-tetra(hydroxyphenyl)chlorin (mTHPC) to cancer cells in vitro. mTHPC was entrapped in NPs (approximately 33 nm diameter) in a monomeric form which produced singlet oxygen with a high efficiency. In aqueous media with high salt concentrations, the NPs underwent aggregation and precipitation but their stability could be preserved in the presence of foetal bovine serum. The cellular uptake, localization and phototoxic activity of mTHPC was determined comparatively in human oesophageal cancer cells after its delivery by the NPs and the standard solvent ethanol/poly(ethylene glycol) 400/water (20:30:50, by vol). The NP formulation reduced the cellular uptake of mTHPC by about 50% in comparison to standard solvent while it did not affect the concentration-dependent photokilling activity of mTHPC and its intracellular localization. Fluorescence resonance energy transfer measurements, using NPs with mTHPC physically entrapped and a cyanine covalently linked, and ultracentrifugation experiments indicated that mTHPC is transferred from NPs to serum proteins when present in the medium. However, the coating of the NP surface with poly(ethylene glycol) largely prevented the transfer to proteins. In conclusion, mTHPC is rapidly transferred from the uncoated nanoparticles to the serum proteins and then internalized by the cells as a protein complex, irrespective of its modality of delivery.


Assuntos
Proteínas Sanguíneas/metabolismo , Mesoporfirinas/farmacocinética , Nanopartículas/química , Siloxanas/metabolismo , Animais , Proteínas Sanguíneas/química , Bovinos , Linhagem Celular Tumoral , Transferência Ressonante de Energia de Fluorescência , Humanos , Mesoporfirinas/química , Fotoquimioterapia , Siloxanas/química
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