Influência do glicocálix e da corona proteica na internalização celular de nanopartículas de sílica
Data
2022-07-29
Autores
Assis, Isabela Ferreira de 
Orientadores
Sousa, Alioscka Augusto
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
A nanomedicina apresenta como um dos seus principais objetivos o desenvolvimento de nanopartículas (NPs) para aplicações biomédicas diversas. Nas últimas décadas, muitos estudos foram realizados com a finalidade de caracterizar e entender as biointerações de NPs com as células, por exemplo, buscando compreender melhor os fatores que influenciam na internalização celular das partículas para sua utilização como carreadores de fármacos, dentre outras funções. Compreender os fatores que regulam a endocitose de NPs constitui, portanto, um dos objetivos principais da nanomedicina. No entanto, apesar de décadas de estudo na área, prever (ou mesmo explicar) resultados específicos permanece um desafio. Isso não é surpreendente, considerando os vários fatores que podem influenciar as interações NP–célula e os processos endocíticos decorrentes. Um desses fatores diz respeito à formação de uma corona proteica nas NPs, definida como uma camada de proteínas fortemente adsorvidas, que medeia as interações entre as partículas e as células. Um segundo fator crucial que influencia as interações NP–célula e a endocitose das NPs diz respeito aos glicosaminoglicanos (GAGs) carregados negativamente que integram o glicocálix celular, uma malha de açúcares que reveste a membrana plasmática. É razoável supor que o glicocálix possa agir tanto no sentido de dificultar quanto de facilitar a endocitose dependendo das características das NPs. Apesar de sua importância, até agora apenas alguns estudos examinaram o impacto do glicocálix na internalização celular de NPs. Dessa maneira, o presente trabalho buscou compreender o papel dos GAGs na endocitose de NPs de sílica de 70 nm de diâmetro recobertas por coronas de albumina bovina, soro fetal bovino, e albumina catiônica, permitindo averiguar o efeito da composição da corona nas interações com o glicocálix e na endocitose. A endocitose das NPs foi estudada em células CHO-K1 (selvagem), pgsA-745 (mutante deficiente da síntese de GAGs), e CHO-K1 na presença de GAGs exógenos adicionados ao meio. Os resultados demonstraram a importância da carga das NPs nas suas interações com os GAGs, uma vez que as NPs catiônicas foram endocitadas de maneira muito mais eficiente em relação às demais. Além disso, os resultados sugeriram que os GAGs das células CHO não atuam como barreira física frente às NPs, mas sim como intermediadores, facilitando a endocitose das mesmas.
Nanomedicine has as one of its main objectives the development of nanoparticles (NPs) for various biomedical applications. In recent decades, many studies have been conducted with the purpose of characterizing and understanding the biointeractions of NPs with cells, for example, seeking to better understand the factors that influence the cellular internalization of particles for their use as drug carriers, among other applications. Understanding the factors that regulate the cellular endocytosis of NPs is therefore one of the main goals of nanomedicine. However, despite decades of study in the field, predicting (or even explaining) specific results remains a challenge. This is not surprising considering the many factors that can influence NP-cell interactions and the resulting endocytic processes. One of these factors concerns the formation of the protein corona around the NPs, defined as a layer of strongly adsorbed proteins, which mediates the interactions between particles and cells. A second crucial factor that influences NP-cell interactions and NP endocytosis concerns the negatively charged glycosaminoglycans (GAGs) that integrate the cellular glycocalyx, a mesh of sugars that coats the plasma membrane. It is reasonable to assume that the glycocalyx can either hinder or facilitate endocytosis depending on the NP characteristics. Despite its importance, so far only a few studies have examined the impact of the glycocalyx on NP cell uptake. Thus, the present study sought to understand the role of GAGs in the endocytosis of 70 nm-diameter silica NPs covered by coronas of bovine albumin, fetal bovine serum, and cationic albumin, enabling to verify the effect of corona composition on NP interactions with the glycocalyx and NP endocytosis. NP uptake was studied in wild-type CHO-K1 cells, pgsA-745 cells (mutated cells deficient in the synthesis of GAGs), and CHO-K1 cells in the presence of exogenous GAGs added to the medium. The results demonstrated the importance of the charge of NPs in their interactions with the GAGs, since cationic NPs were endocytosed much more efficiently than the other two particle types. In addition, the results suggested that the GAGs of CHO cells do not act as a physical barrier against NP uptake, but rather mediate NP-cell interactions and NP endocytosis.
Nanomedicine has as one of its main objectives the development of nanoparticles (NPs) for various biomedical applications. In recent decades, many studies have been conducted with the purpose of characterizing and understanding the biointeractions of NPs with cells, for example, seeking to better understand the factors that influence the cellular internalization of particles for their use as drug carriers, among other applications. Understanding the factors that regulate the cellular endocytosis of NPs is therefore one of the main goals of nanomedicine. However, despite decades of study in the field, predicting (or even explaining) specific results remains a challenge. This is not surprising considering the many factors that can influence NP-cell interactions and the resulting endocytic processes. One of these factors concerns the formation of the protein corona around the NPs, defined as a layer of strongly adsorbed proteins, which mediates the interactions between particles and cells. A second crucial factor that influences NP-cell interactions and NP endocytosis concerns the negatively charged glycosaminoglycans (GAGs) that integrate the cellular glycocalyx, a mesh of sugars that coats the plasma membrane. It is reasonable to assume that the glycocalyx can either hinder or facilitate endocytosis depending on the NP characteristics. Despite its importance, so far only a few studies have examined the impact of the glycocalyx on NP cell uptake. Thus, the present study sought to understand the role of GAGs in the endocytosis of 70 nm-diameter silica NPs covered by coronas of bovine albumin, fetal bovine serum, and cationic albumin, enabling to verify the effect of corona composition on NP interactions with the glycocalyx and NP endocytosis. NP uptake was studied in wild-type CHO-K1 cells, pgsA-745 cells (mutated cells deficient in the synthesis of GAGs), and CHO-K1 cells in the presence of exogenous GAGs added to the medium. The results demonstrated the importance of the charge of NPs in their interactions with the GAGs, since cationic NPs were endocytosed much more efficiently than the other two particle types. In addition, the results suggested that the GAGs of CHO cells do not act as a physical barrier against NP uptake, but rather mediate NP-cell interactions and NP endocytosis.