Silica nanoparticle-generated ROS as a predictor of cellular toxicity: mechanistic insights and safety by design

Jeong

Hong

et al. 2016

Sci Rep

Ocular drug delivery is an interesting field in current research. Silica nanoparticles (SiNPs) are promising drug carriers for ophthalmic drug delivery. However, little is known about the toxicity of SiNPs on ocular surface cells such as human corneal epithelial cells (HCECs). In this study, we evaluated the cytotoxicity induced by 50, 100 and 150 nm sizes of SiNPs on cultured HCECs for up to 48 hours. SiNPs were up-taken by HCECs inside cytoplasmic vacuoles. Cellular reactive oxygen species generation was mildly elevated, dose dependently, with SiNPs, but no significant decrease of cellular viability was observed up to concentrations of 100 μg/ml for three different sized SiNPs. Western blot assays revealed that both cellular autophagy and mammalian target of rapamycin (mTOR) pathways were activated with the addition of SiNPs. Our findings suggested that 50, 100 and 150 nm sized SiNPs did not induce significant cytotoxicity in cultured HCECs.

Section: Discussionmentioning

confidence: 66%

The Effect of Silica Nanoparticles on Human Corneal Epithelial Cells

Jeong

Hong

et al. 2016

Sci Rep

“…SiNPs induced a mild increase of ROS and the viability of HCEC at concentrations up to 100 μ g/ml. Cellular oxidative stress or ROS generation can be a useful predictor of SiNPs induced nanotoxicity [40][41][42] . However, we found the cell viability of HCECs was not affected significantly despite the mild elevation of ROS with SiNPs addition.…”

Section: Discussionmentioning

confidence: 99%

The effect of silica nanoparticles on human corneal epithelial cells

Yim

et al. 2016

Acta Ophthalmologica

1Ocular drug delivery is an interesting field in current research. Silica nanoparticles (SiNPs) are promising drug carriers for ophthalmic drug delivery. However, little is known about the toxicity of SiNPs on ocular surface cells such as human corneal epithelial cells (HCECs). In this study, we evaluated the cytotoxicity induced by 50, 100 and 150 nm sizes of SiNPs on cultured HCECs for up to 48 hours. SiNPs were uptaken by HCECs inside cytoplasmic vacuoles. Cellular reactive oxygen species generation was mildly elevated, dose dependently, with SiNPs, but no significant decrease of cellular viability was observed up to concentrations of 100 μg/ml for three different sized SiNPs. Western blot assays revealed that both cellular autophagy and mammalian target of rapamycin (mTOR) pathways were activated with the addition of SiNPs. Our findings suggested that 50, 100 and 150 nm sized SiNPs did not induce significant cytotoxicity in cultured HCECs.The cornea is typically the major route of intraocular transport of topically applied drugs 1 . Corneal epithelial cells constitute the outermost mechanical barrier of the ocular surface 2 . These cells are replenished periodically in every 2 weeks by newly differentiated epithelial cells from the limbal area 2,3 . As a most surface layer, corneal epithelial cells are continuously exposed to the outer atmosphere, therefore, they provide the first line of defense against foreign materials invading the ocular surface 2 . This protective role of corneal epithelial cells, on the other hand, sometimes serves as a mechanical barrier for ocular penetration of topically administered medication 1 . To enhance ocular drug penetration, nanoparticle based drug delivery systems have been intensively investigated with promising results [4][5][6] . Amorphous silica nanoparticles (SiNPs) are some of the most promising nanoparticle systems for ocular drug delivery. SiNPs have stable chemical structures, large surface to volume ratios, ease of surface modification and tolerable biodegradability 7 . Due to these physical properties, biomedical applications of SiNPs have been intensively investigated 7,8 . Recent study suggests that small sized (50 nm) silica nanoparticles are readily permeable into de-epithelialized cornea 9 . However, cytotoxicity is the most significant issue with SiNPs. It is known that the cellular toxicity and biological effect of SiNPs are largely dependent on the size and concentration of the SiNPs 10,11 . In addition, different cell types have shown different susceptibility and patterns of SiNPs nanotoxicity 11,12 . Recently, several studies have demonstrated that SiNPs have no direct cytotoxicity on retinal endothelial cells and retinal neuronal tissue 13 . However, the nanotoxicity of SiNPs on corneal epithelial cells is not fully studied yet although these cells are the first encounters when SiNPs are topically administered for ocular therapy.Herein, monodisperse and non-porous SiNPs with diameters of 50, 100 and 150 nm were employed to investigate how particle siz...

“…21 The cytotoxic effect of colloidal Si-NPs is mainly attributed to the high levels of oxidative stress and generation of reactive oxygen species (ROS), mitochondrial damage, and autophagy. [22][23][24] Based on hierarchical oxidative stress hypothesis, high levels of ROS production could cause damages to DNA, proteins, lipids, and cell organelles and eventually lead to the cell death. 25 These particles show toxicity at higher doses, which is both size and surface chemistry dependent.…”

Section: Colloidal Solid Si-npsmentioning

confidence: 99%

“…For example, surface modification of bare Si-NPs with amine groups improves the biocompatibility of Si-NPs both in vitro and in vivo. 24,26 Other findings with regard to the size effect show that smaller particles induce higher cytotoxicity and inflammation in epithelial cells and macrophages, respectively. 27,28 This could possibly be attributed to the higher density of silanol groups on the surface of smaller Si-NPs compared to the large ones.…”

mentioning

confidence: 99%

Facilitating Translational Nanomedicine via Predictive Safety Assessment

et al. 2017

Extensive research on engineered nanomaterials (ENMs) has led to the development of numerous nano-based formulations for theranostic purposes. Although some nano-based drug delivery systems already exist on the market, growing numbers of newly designed ENMs exhibit improved physicochemical properties and are being assessed in preclinical stages. While these ENMs are designed to improve the efficacy of current nanobased therapeutic or imaging systems, it is necessary to thoroughly determine their safety profiles for successful clinical applications. As such, our aim in this mini-review is to discuss the current knowledge on predictive safety and structure-activity relationship (SAR) analysis of major ENMs at the developing stage, as well as the necessity of additional long-term toxicological analysis that would help to facilitate their transition into clinical practices. We focus on how the interaction of these nanomaterials with cells would trigger signaling pathways as molecular initiating events that lead to adverse outcomes. These mechanistic understandings would help to design safer ENMs with improved therapeutic efficacy in clinical settings.During the past decades, engineered nanomaterials (ENMs) have been widely used in biomedical applications, such as nanomedicine, bioimaging, and tissue engineering, because of their unique biophysicochemical properties.1,2 With regard to nanomedicine applications, ENMs could be formulated as drug carriers that deliver the therapeutic reagents within the human body and increase their bioavailability and blood circulation half-life.2 Moreover, these nanocarriers could be functionalized to deliver the drug specifically to the desired target tissues (e.g., tumors) and release the payload sustainably over long periods, thereby eliminating the necessity of multiple drug administration and reducing its cytotoxic side effects toward healthy cells.2 In addition to their implementation in drug delivery, ENMs could be used for diagnostic and imaging purposes that would help to monitor the disease and administer the treatment more accurately. 2Past research in nanomedicine has led to the design of various nanomaterial-based therapeutic and diagnostic systems that are being investigated in experimental stages (e.g., in vitro and in vivo) and clinical trials or are commercially available to the corresponding patients (Table 1). Most commercialized nanomaterial-based therapeutic reagents use lipids, proteins, and polymers that could self-assemble and biodegrade with few side effects.3 Because of high biocompatibility of lipids, several commercial liposome-drug formulations have been developed, mostly relying on polyethylene glycol (PEG)-conjugated lipids, such as DOXIL, AmBisome, Epaxal, and Inflexal V, and are under clinical trials focusing on various types of disease treatments. 4,5 Polymer-based nanoparticles (NPs) also present low toxicity, but their surface functionalization may affect their safety. The most commonly used materials include PEG, ploy(lactic-co-glycolic) acid (PLGA...