Efeitos biológicos de citrato de ródio II livre e de sua associação a nanopartículas magnéticas e a magnetolipossomas em células de carcinoma mamário : estudos in vitro e in vivo

Tese (doutorado)—Universidade de Brasília, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biologia Molecular, 2011.O aumento da incidência do câncer de mama e suas limitações terapêuticas, atualmente empregadas, suscitam a busca de alternativas terapêuticas mais eficazes. Dentre compostos com potencial terapêutico, o citrato de ródio (II) (Rh2(H2 cit)4 ), um membro da família dos carboxilatos de ródio, é promissor por apresentar atividade citotóxica, citostática e antitumoral em células de carcinoma de origem mamária (Ehrlich) e em células tumorais (Y-1) e normais da adrenocortical (AR-1(6)). Contudo, a introdução deste composto em estudos pré-clínicos tem sido limitada devido à sua toxicidade. Nanopartículas de maghemita (NPM) e magnetolipossomas (ML) representam uma plataforma atrativa como sistemas carreadores para entrega de drogas, pois podem agir de forma específica em células tumorais. Portanto, a associação entre Rh2 (H2 cit)4 e NPM ou ML representa uma estratégia potencial para reduzir a toxicidade de Rh2 (H2 cit)4 e, assim, melhorar sua ação terapêutica. Nesta pesquisa, reportamos efeitos biológicos de Rh2 (H2 cit)4 livre e do Rh2 (H2 cit)4 associado a NPM ou ML sobre carcinoma mamário tanto em cultura de células (MCF-7 e 4T1) como em camundongos Balb/c portadores de carcinoma. Células normais (MCF-10A) e camundongos sadios também foram utilizados neste estudo para fins comparativos. O efeito citotóxico de Rh2 (H2 cit)4 livre foi dependente da dose, do tempo e do tipo de linhagem celular. De uma forma geral, este efeito foi mais intenso após 72 h com doses acima de 500 pM e em células normais da mama (MCF-10A) (p<0.05). Os efeitos citotóxicos de Rh2 (H2 cit)4 livre foram evidenciados por alterações morfológicas, como condensação e fragmentação nuclear, formação de blebbing, exposição de fosfatidilserina na membrana plasmática, redução dos filamentos de actina e condensação mitocondrial. Nos tratamentos com 50 pM de Rh2 (H2 cit)4 associado a NPM (Magh-Rh2 (H2 cit)4 ) e a ML (LÍp-Magh-Rh2 (H2 cit)4 ) houve um efeito citotóxico mais pronunciado em células de carcinoma (MCF-7 e 4T1) do que em células normais (MCF-10A) (p<0.05). Além disso, verificou-se que as composições de Rh2 (H2 cit)4 e Magh-Rh2 (H2 cit)4 apresentaram atividade antitumoral em camundongos portadores de carcinoma mamário e no grupo de animais tratados com Magh-Rh2 (H2 cit)4 houve maior sobrevida em relação aos animais tratados com Rh2 (H2 cit)4 . Por meio das análises histopatológicas e ultraestruturais, observou-se que os tratamentos com Rh2 (H2 cit)4 e Magh-Rh2 (H2 cit)4 induziram apoptose, necrose e fibrose no tecido tumoral. Também foram notados nestes tecidos NPM no citoplasma e no núcleo celular. Em relação às análises de toxicidade, observou-se linfocitopenia no grupo de animais tratados com MaghRh2 (H2 cit)4 e aumento da fragmentação do DNA de células da medula óssea em animais tratados com Rh2 (H2 cit)4 , mas alterações citostáticas nestas células e bioquímicas (creatinina, ferro sérico, transaminase pirúvica) não foram notadas entre todos os grupos experimentais. De uma forma geral, concluímos que os tratamentos com as composições Rh2 (H2 cit)4 , Magh-Rh2 (H2 cit)4 e Lip-Magh-Rh2 (H2 cit)4 apresentaram potencial terapêutico para carcinoma mamário.The increase incidence of breast cancer and its therapeutic limitations, currently employed, demand the search for alternative therapies. Among compounds with therapeutic potential, the rhodium (II) citrate (Rh2 (H2 cit)4 ), a member of the family of rhodium carboxylates, is promising due to its cytotoxic, cytostatic and antitumor activity in mammary carcinoma cells (Ehrlich) and in adrenocortical tumor (Y-1) and normal cells (AR-1(6)). However, the introduction of this compound in preclinical studies has been limited due to its toxicity. Maghemite nanoparticles (NPM) and magnetoliposomes (ML) represent an attractive platform as carrier systems for drug delivery because they can act specifically on tumor cells. Therefore, the association between Rh2 (H2 cit)4 with NPM or ML represents a potential strategy to reduce the Rh2 (H2 cit)4 toxicity and to improve its therapeutic action. In this research, we report the biological effects of free Rh2 (H2 cit)4 and Rh2 (H2 cit)4 associated with NPM or ML on breast cancer both in cultured cells (MCF-7 and 4T1) and in Balb/c mice bearing carcinoma. Normal cells (MCF-10A) and healthy mice were also used in this study for comparison purposes. The cytotoxic effect of Rh2 (H2 cit)4 was more intense after 72 h with doses above 500 pM and in normal breast cells (MCF-10A) (p<0.05). The cytotoxic effects of free Rh2 (H2 cit)4 were evidenced by morphological changes such as nuclear condensation and fragmentation, formation of blebbing, phosphatidylserine exposure on the plasma membrane, reduction of actin and mitochondrial condensation. In treatments with 50 pM Rh2 (H2 cit)4 associated with NPM (Magh-Rh2 (H2 cit)4 ) and ML (Lip-Magh-Rh2 (H2 cit)4 ) the cytotoxic effect was more pronounced in carcinoma cells (MCF-7 and 4T1) than in normal cells (MCF-10A) (p <0.05). Moreover, it was found that Rh2 (H2 cit)4 and Magh-Rh2 (H2 cit)4 showed antitumor activity in mice bearing breast carcinoma, with increased survival rate in animals treated with Magh-Rh2 (H2 cit)4 . By histopathological and ultrastructural analysis, we found that treatment with Rh2 (H2 cit)4 and Magh-Rh2 (H2 cit)4 induced apoptosis, necrosis and fibrosis in tumor tissue. Also, NPM were found in these tissues both in the cytoplasm and in the nucleus. Regarding the toxicity analysis, lymphocytopenia was observed in animals treated with Magh-Rh2 (H2 cit)4 . Besides, a slight increase of DNA fragmentation of bone marrow cells was also noted in animals treated with Rh2 (H2 cit)4 , although biochemical and cytostatic alterations were not seen among all groups. In summary, we conclude that treatments with Rh2 (H2 cit)4 , Magh-Rh2 (H2 cit)4 and Lip-Magh-Rh2 (H2 cit)4 compositions showed therapeutic potential for breast carcinoma

Diabetes Ground Control: A Novel System for Correcting Anomalous Stride in Diabetic Patients

Diabetes mellitus is a chronic disease characterized by several complications, including diabetic foot, a serious problem induced by increased foot plantar pressure during gaiting. This misbehavior intensifies the risk of ulceration, which may lead to minor and major amputations. This study proposes the inclusion of a passive element to correct diabetic stride, namely the Diabetes Ground Control (DGC), a customized latex-based insole designed to perform load redistribution along the entire foot length, and by so minimizing overload and pressure levels on the foot sole of diabetic patients. A mathematical model in state space for the DGC system is proposed and dynamically characterized using polynomial chaos analysis. The inclusion of the DGC element reduced considerably the amplitude of foot pressure oscillations during walking. Hence, the DGC, which can be customized according to the patient’s physical characteristics and weight, is a potential instrument for controlling the tensions on the diabetic foot

Morphological Alterations and G0/G1 Cell Cycle Arrest Induced by Curcumin in Human SK-MEL-37 Melanoma Cells

ABSTRACT: The aim of this work was to study the effect of curcumin on cell cycle in the human SK-MEL-37 melanoma cell line. In addition, morphological and structural analyses were also performed. Flow cytometric analysis showed a G0/G1 arrest at 5 µM after 24 h exposure and a concentration-dependent increase in the proportion of sub-G0 hypodiploid cells. Typical apoptotic events were also observed by the fluorescence microscopy, transmission and scanning electronic microscopy. Loss of mitochondrial membrane potential was not detected. Results suggested that curcumin could arrest human melanoma cells at G0/G1 phase and induce a mitochondrial-independent apoptotic pathway. _______________________________________________________________________________ RESUMOO melanoma é um tipo agressivo de câncer cujo tratamento culmina com o estabelecimento de resistência aos quimioterápicos empregados. Portanto, é importante o desenvolvimento de novos agentes farmacológicos que sejam menos tóxicos e que não provoquem quimiorresistência. As inúmeras propriedades terapêuticas da curcumina vêm sendo confirmadas através de estudos sobre o seu mecanismo de ação em células cultivadas. No presente estudo, empregamos células de melanoma humano da linhagem SK-MEL-37, que desenvolveram resistência in vitro à doxorubicina e cisplatina, drogas normalmente utilizadas na clínica. Investigamos o efeito da curcumina sobre o ciclo celular através de citometria de fluxo. Além disso, análises morfológicas e estruturais também foram realizadas. Os resultados demonstraram que o tratamento com uma concentração de 5 ?M de curcumina provocou uma parada na subfase G0/G1. Além disso, observou-se um aumento dose-dependente na proporção de células hipodiplóides em sub-G0. Eventos apoptóticos típicos foram observados por microscopia de fluorescência, microscopia eletrônica de transmissão e microscopia eletrônica de varredura. Não foi detectada alteração no potencial de membrana mitocondrial. Os resultados indicam que futuros estudos poderão tornar possível a utilização da curcumina como um modulador para agentes quimioterápicos empregados na clínica no tratamento do melanoma

Characterization of the cicatrization process in diabetic foot ulcers based on the production of reactive oxygen species

The present study aims at evaluating the correlation between the free radical formation and the healing action of lower limbs’ ulcers in a randomized controlled trial with the use of an adhesive derived from natural latex associated with a light-emitting diode (LED) circuit. The sample consists of 15 participants with lower limb lesions divided into three groups: group 1 case (5 participants) received the proposed dressing system adhesive of the natural latex associated with the LED circuit; group 2 control (5 participants) received the dressings at home performed by nurses according to and established by the clinic of wounds (treated with calcium alginate or silver foam); and group 3 (5 participants) also received the dressing in their homes with the use of the dressing adhesive derived from the natural latex associated with the LED circuit. The collected data were analyzed qualitatively and quantitatively by electron paramagnetic resonance for determination of free radical formation. Kruskal-Wallis statistical test was used to evaluate the effect of treatment on the lower limb’s ulcer cicatrization process and its correlation with free radical. The results obtained corroborated the hypothesis about the reduction of the quantity of these molecules in the end of treatment related to the healing wound

Antitumor effect and toxicity of free rhodium (II) citrate and rhodium (II) citrate-loaded maghemite nanoparticles in mice bearing breast cancer

Background: Magnetic fluids containing superparamagnetic iron oxide nanoparticles represent an attractive platform as nanocarriers in chemotherapy. Recently, we developed a formulation of maghemite nanoparticles coated with rhodium (II) citrate, which resulted in in vitro cytotoxicity enhanced up to 4.6 times when compared to free rhodium (II) citrate formulation on breast carcinoma cells. In this work, we evaluate the antitumor activity and toxicity induced by these formulations in Balb/c mice bearing orthotopic 4T1 breast carcinoma. Methods: Mice were evaluated with regard to the treatments’ toxicity through analyses of hemogram, serum levels of alanine aminotransferase, iron, and creatinine; DNA fragmentation and cell cycle of bone marrow cells; and liver, kidney and lung histology. In addition, the antitumor activity of rhodium (II) citrate and maghemite nanoparticles coated with rhodium (II) citrate was verified by tumor volume reduction, histology and immunohistochemistry. Results: Regarding the treatments’ toxicity, no experimental groups had alterations in levels of serum ALT or creatinine, and this suggestion was corroborated by the histopathologic examination of liver and kidney of mice. Moreover, DNA fragmentation frequency of bone marrow cells was lower than 15% in all experimental groups. On the other hand, the complexes rhodium (II) citrate-functionalized maghemite and free rhodium (II) citrate led to a marked growth inhibition of tumor and decrease in CD31 and Ki-67 staining. Conclusions: In summary, we demonstrated that both rhodium (II) citrate and maghemite nanoparticles coated with rhodium (II) citrate formulations exhibited antitumor effects against 4T1 metastatic breast cancer cell line following intratumoral administration. This antitumor effect was followed by inhibition of both cell proliferation and microvascularization and by tumor tissue injury characterized as necrosis and fibrosis. Remarkably, this is the first published report demonstrating the therapeutic efficacy of maghemite nanoparticles coated with rhodium (II) citrate. This treatment prolonged the survival period of treated mice without inducing apparent systemic toxicity, which strengthens its use for future breast cancer therapeutic applications

Benefits of using polymeric nanoparticles in breast cancer treatment : a systematic review

Instituto de Ciências Biológicas (IB)Departamento de Genética e Morfologia (IB GEM)Faculdade UnB Gama (FGA)Programa de Pós-Graduação em Engenharia Biomédic

Liposomes Composed by Membrane Lipid Extracts from Macrophage Cell Line as a Delivery of the Trypanocidal N,N’-Squaramide 17 towards Trypanosoma cruzi

Chagas is a neglected tropical disease caused by Trypanosoma cruzi, and affects about 25 million people worldwide. N, N&rsquo;-Squaramide 17 (S) is a trypanocidal compound with relevant in vivo effectiveness. Here, we produced, characterized, and evaluated cytotoxic and trypanocidal effects of macrophage-mimetic liposomes from lipids extracted of RAW 264.7 cells to release S. As results, the average hydrodynamic diameter and Zeta potential of mimetic lipid membranes containing S (MLS) was 196.5 &plusmn; 11 nm and &minus;61.43 &plusmn; 2.3 mV, respectively. Drug entrapment efficiency was 73.35% &plusmn; 2.05%. After a 72 h treatment, MLS was observed to be active against epimastigotes in vitro (IC50 = 15.85 &plusmn; 4.82 &mu;M) and intracellular amastigotes (IC50 = 24.92 &plusmn; 4.80 &mu;M). Also, it induced low cytotoxicity with CC50 of 1199.50 &plusmn; 1.22 &mu;M towards VERO cells and of 1973.97 &plusmn; 5.98 &mu;M in RAW 264.7. MLS also induced fissures in parasite membrane with a diameter of approximately 200 nm in epimastigotes. MLS showed low cytotoxicity in mammalian cells and high trypanocidal activity revealing this nanostructure a promising candidate for the development of Chagas disease treatment