In vivo and in vitro toxicity evaluation of liposome-encapsulated sirolimus.

BACKGROUND: To evaluate the in vivo and in vitro toxicity of a new formulation of liposome-encapsulated sirolimus (LES). METHODS: In vitro experiments were done using ARPE-19 and HRP cells. An MTT assay was used to determine cell metabolic activity and a TUNEL assay for detecting DNA fragmentation. In vivo experiments were conducted on New Zealand albino rabbits that received intravitreal injections of empty liposomes (EL) or different concentrations of LES. Histopathological and immunohistochemical analyses were performed on the rabbit's eyes following injection. RESULTS: Eighteen eyes of nine rabbits were used. MTT assay cell viability was 95.04% in group 1 (12.5 µL/mL LES). 92.95% in group 2 (25 µL/mL LES), 91.59% in group 3 (50 µL/mL LES), 98.09% in group 4 (12.5 µL/mL EL), 95.20% on group 5 (50 µL/mL EL), 98.53% in group 6 (50 µL/mL EL), and 2.84% on group 8 (50 µL/mL DMSO). There was no statistically significant difference among groups 1 to 7 in cell viability (p = 1.0), but the comparison of all groups with group 8 was significant (p < 0.0001). The TUNEL assay comparing two groups was not statistically significant from groups 1 to 7 (p = 1.0). The difference between groups 1 to 7 and group 8 (p < 0.0001) was significant. Histopathological changes were not found in any group. No activation of Müller cells was detected. CONCLUSION: A novel formulation of LES delivered intravitreally did not cause in vitro toxicity, as evaluated by MTT and TUNEL assays, nor in vivo toxicity as evaluated by histopathology and immunohistochemistry in rabbit eyes.

Retinal changes in rabbit after intravitreal injection of sunitinib encapsulated into solid lipid nanoparticles and polymeric nanocapsules / Avaliação das alterações retinais no coelho após injeção intravítrea de sunitinib encapsulado em nanoparticulas lípidas sólidas e nanocapsulas polímeros

ABSTRACT Purpose: We aimed to evaluate the safety of single intravitreal injection of each of two concentrations of 0.1 ml of sunitinib (1 and 10 mg/ml), 0.1 ml of a drug-free dispersion containing solid lipid nanoparticles, and 0.1 ml of a drug-free dispersion containing polymeric nanocapsules for analyzing the possible toxic effects using electrophysiology and histology in albino rabbit retina. Methods: We conducted an experimental controlled study of 20 eyes of albino rabbits. Intravitreal injections of each specific agent were applied to one eye per rabbit in each 5-rabbit group, while the contralateral eyes received no treatment and were used as controls. Results: We noted no electroretinographic changes in the sunitinib (1 and 10 mg/ml) or in solid lipid nanoparticles groups. However, we observed significant abnormalities in ocular morphology and in the electroretinogram in the nanocapsules group. At the histological level, only the nanocapsules group demonstrated abnormal changes, including severe edema and cytoplasmic vacuole formation. Conclusions: While nanocapsules intravitreal injections indicated retinal toxic effects, sunitinib and solid lipid nanoparticles intravitreal injections were not toxic to the retina. Our results suggest that a sunitinib preparation with solid lipid nanoparticles for controlled release may offer a significant therapeutic approach for vasoproliferative ocular disease.

RESUMO Objetivos: O presente estudo teve por objetivo avaliar a segurança da injeção intravítrea de 0,1 ml de sunitinibe em duas concentrações (1 mg/ml e 10 mg/ml), 0,1 ml de dispersão contendo nanopartículas lipídicas sólidas sem droga e 0,1 ml de dispersão contendo nanocápsulas poliméricas livre de drogas analisando os possíveis efeitos tóxicos à retina de coelhos albinos detectados pela eletrofisiologia e histologia por microscopia óptica. Métodos: Um estudo controlado experimental foi rea­lizado com 20 olhos de coelhos albinos. Foram realizadas injeções intravítrea de duas concentrações diferentes de suniti­nibe, uma dispersão contendo nanopartículas lipídicas sólidas e uma dispersão contendo nanocápsulas. O olho contralateral não recebeu tratamento e foi utilizado como controle. Resultados: Não foram observadas alterações eletrorretinográficas nos grupos do sunitinibe (1 mg/ml e 10 mg/ml) e no grupo das nanopartículas lipídicas sólidas. No grupo das nanocápsulas, houve alterações significativas tanto na morfologia, quanto na amplitude e tempo das ondas do eletrorretinograma. Ao estudo histológico, somente o grupo das nanocápsulas apresentou al­terações degenerativas (núcleos tumefeitos) com acentuado edema e formação de vacúolos citoplasmáticos, sugerindo toxidade retiniana. Conclusões: As injeções intravítreas de sunitinibe e nanopartículas lipídicas sólidas não foram tóxicas para a retina. No entanto, nanocápsulas mostraram ser tóxicas para a retina. Sendo assim, a possibilidade de poder combinar o potencial de uma droga que possui a capacidade de inibir duas importantes vias da angiogênese, às vantagens de liberação controlada das nanopartículas lipídicas sólidas, pode ser um importante recurso terapêutico para doenças vasoproliferativas oculares.

Retinal changes in rabbit after intravitreal injection of sunitinib encapsulated into solid lipid nanoparticles and polymeric nanocapsules.

PURPOSE: We aimed to evaluate the safety of single intravitreal injection of each of two concentrations of 0.1 ml of sunitinib (1 and 10 mg/ml), 0.1 ml of a drug-free dispersion containing solid lipid nanoparticles, and 0.1 ml of a drug-free dispersion containing polymeric nanocapsules for analyzing the possible toxic effects using electrophysiology and histology in albino rabbit retina. METHODS: We conducted an experimental controlled study of 20 eyes of albino rabbits. Intravitreal injections of each specific agent were applied to one eye per rabbit in each 5-rabbit group, while the contralateral eyes received no treatment and were used as controls. RESULTS: We noted no electroretinographic changes in the sunitinib (1 and 10 mg/ml) or in solid lipid nanoparticles groups. However, we observed significant abnormalities in ocular morphology and in the electroretinogram in the nanocapsules group. At the histological level, only the nanocapsules group demonstrated abnormal changes, including severe edema and cytoplasmic vacuole formation. CONCLUSIONS: While nanocapsules intravitreal injections indicated retinal toxic effects, sunitinib and solid lipid nanoparticles intravitreal injections were not toxic to the retina. Our results suggest that a sunitinib preparation with solid lipid nanoparticles for controlled release may offer a significant therapeutic approach for vasoproliferative ocular disease.

A Novel Polymer-Lipid Hybrid Nanoparticle for the Improvement of Topotecan Hydrochloride Physicochemical Properties.

BACKGROUND: Topotecan (TPT) is a water-soluble derivate of camptothecin, which undergoes ring-opening hydrolysis in neutral solutions, leading to stability loss and poor cellular uptake. Lipid nanoencapsulation can improve TPT stability, and polymer-lipid hybrid nanoparticles (PLN) are interesting alternatives to improve TPT nanoencapsulation. OBJECTIVE: This study seeks to prepare complexes between the cationic TPT and the negatively charged dextran sulfate (DS) with a view of improving drug loading, chemical stability and release control. METHODS: The optimum ionic molar ratio in DS-TPT complexation was determined, and the selected complex was characterized by FTIR and solid-state 13C NMR. TPT solubility in the free and complexed forms was also assayed. TPT-PLN was then obtained via a microemulsion technique, and particle size, zeta potential, encapsulation efficiency, drug loading and drug recovery were determined. Additionally, the TPT stability and in vitro release were determined from PLN and compared with free TPT, TPT-DS complex and TPT encapsulated in nanostructured lipid carriers (NLC) of similar composition. RESULTS: TPT-DS complexation was confirmed by FTIR and NMR. TPT solubility in the complex was drastically decreased when compared to free TPT. TPT-PLN had high encapsulation efficiency (97%) and drug loading capacity (5.5%). Additionally, TPT-PLN showed a mean diameter, polidispersivity index e zeta potential of 140 nm, 0.2 and -22 mV, respectively. The TPT chemical stability and release from PLN were observed to be superior when compared to NLC. CONCLUSION: PLN has shown to be a more effective nanosystem for TPT nanoencapsulation because TPT loading, stability and release were superior when compared to TPT-NLC.

Aplicações das nanopartículas lipídicas no tratamento de tumores sólidos: revisão de literatura / Applications of lipid nanocarriers for solid tumors therapy: literature review / Aplicaciones de las nanopartículas lipídicas el tratamiento de tumores sólidos: revisión de la literatura

Introdução: Os nanocarreadores lipídicos são sistemas utilizados para direcionar fármacos especificamente para seu sítio de ação e têm atraído bastante atenção da comunidade científica por serem biocompatíveis e biodegradáveis. Esses sistemas podem direcionar fármacos para os tumores sólidos, possibilitando uma liberação prolongada no sítio de ação e, com isso, ampliando a utilidade da quimioterapia antineoplásica. Objetivo: Revisar a literatura disponível sobre os estudos in vivo envolvendo nanocarreadores lipídicos contendo fármacos citotóxicos, voltados ao tratamento de tumores sólidos. Método: Pesquisa realizada na base de dados Pubmed®, no período temporal de 2007 até 2011,utilizando os descritores: liposomes; lipid nanoparticles; cancer; in vivo; com o operador booleano and entre eles, eminglês. Resultados: Foram encontrados 1.595 trabalhos relacionados com o uso de lipossomas e 77 relacionados àsnanopartículas lipídicas. Poucos trabalhos têm relatado a avaliação in vivo das nanopartículas lipídicas (28 trabalhos), comparado ao observado para os lipossomas (472 trabalhos), desde que os lipossomas foram desenvolvidos duas décadasantes das nanopartículas lipídicas. Quatro medicamentos com lipossomas já estão aprovados e são utilizados na clínica, ao passo que apenas uma preparação com nanopartículas lipídicas está sob investigação clínica, em fase I. Conclusão: De forma geral, o número de trabalhos relativos ao uso da nanotecnologia para o tratamento do câncer tem aumentado rapidamente, tornando importante saber diferenciar os diversos tipos de nanocarreadores e, principalmente, conhecer quais já estão em uso na clínica. Existem poucos estudos clínicos com os nanocarreadores lipídicos, entretanto esses sistemas apresentam enorme potencial para melhorar a prática clínica na oncologia