The protection of cells from nitric oxide-mediated apoptotic death by mechanochemically synthesized fullerene (C60) nanoparticles

Aggregation-free and high stability core-shell polymer nanoparticles with high fullerene loading capacity, variable fullerene type, and compatibility towards biological conditions

Fullerenes have unique structural and electronic properties that make them attractive candidates for diagnostic, therapeutic, and theranostic applications. However, their poor water solubility remains a limiting factor in realizing their full biomedical potential. Here, we present an approach based on a combination of supramolecular and covalent chemistry to access well-defined fullerene-containing polymer nanoparticles with a core-shell structure. In this approach, solvophobic forces and aromatic interactions first come into play to afford a micellar structure with a poly(ethylene glycol) shell and a corannulene-based fullerene-rich core. Covalent stabilization of the supramolecular assembly then affords core-crosslinked polymer nanoparticles. The shell makes these nanoparticles biocompatible and allows them to be dried to a solid and redispersed in water without inducing interparticle aggregation. The core allows a high content of different fullerene types to be encapsulated. Finally, covalent stabilization endows nanostructures with stability against changing environmental conditions.

Striking Effect of Polymer End-Group on C60 Nanoparticle Formation by High Shear Vibrational Milling with Alkyne-Functionalized Poly(2-oxazoline)s

Buckminsterfullerene (C₆₀) has a large potential for biomedical applications. However, the main challenge for the realization of its biomedical application potential is to overcome its extremely low water solubility. One approach is the coformulation with biocompatible water-soluble polymers, such as poly(2-oxazoline)s (PAOx), to form water-soluble C₆₀ nanoparticles (NPs). However, uniform and defined NPs have only been obtained via a thin film hydration method or using cyclodextrin-functionalized PAOx. Here, we report the mechanochemical preparation of defined and stable C₆₀:PAOx NPs by the introduction of a simple alkyne group as a polymer end-group. The presence of this alkyne bond is proven to be crucial in the mechanochemical synthesis of stable, defined sub-100 nm C₆₀:PAOx NPs, with high C₆₀ content up to 8.9 wt %.

Fullerenol Nanoparticles Decrease Blood-Brain Barrier Interruption and Brain Edema during Cerebral Ischemia-Reperfusion Injury Probably by Reduction of Interleukin-6 and Matrix Metalloproteinase-9 Transcription

BACKGROUND

The present study aimed to examine the protective role of fullerenol nanoparticles against blood-brain barrier (BBB) interruption and brain edema during cerebral ischemia-reperfusion injury probably by reduction of interleukin-6 (IL-6) and matrix metalloproteinase-9 (MMP-9) transcription.

METHODS

The male Wistar rats (weighting 280-320 g) were randomly assigned into four groups as follows: sham, control ischemic, pretreated ischemic, and posttreated ischemic groups. Cerebral ischemia-reperfusion (IR) injury was performed by occlusion of middle cerebral artery (MCA) for 90 minutes followed by twenty-four hours reperfusion. Rats were administered fullerenol 5mg/kg, intraperitoneally, 30 minutes before induction of IR in pretreated ischemic group and immediately after termination of MCA occlusion in posttreated ischemic group. After twenty-four hours reperfusion, the method of Evans blue dye extravasation (EBE) and RT-PCR were used for determination of BBB permeability and mRNA expression levels of MMP-9 and IL-6, respectively. Neuronal deficit score (NDS) and edema of the ischemic hemispheres were also evaluated.

RESULTS

MCA occlusion increased NDS in control ischemic rats (3.16 ± 0.16) with concomitant increase in EBE (15.30 ± 3.98µg/g) and edema (3.53 ± 0.50%). Fullerenol in both pretreated and posttreated ischemic groups reduced NDS (36% and 68%, respectively), EBE (89% and 91%, respectively) and edema (53% and 81%, respectively). Although MCA occlusion increased the mRNA expression levels of MMP-9 and IL-6 in ischemic hemispheres, fullerenol in both treatment groups noticeably decreased the mRNA expression levels of these genes.

CONCLUSION

In conclusion, fullerenol nanoparticles can protect BBB integrity and attenuate brain edema after cerebral ischemia-reperfusion injury possibly by reduction of IL-6 and MMP-9 transcription.

Ultrahigh-yield synthesis of N-doped carbon nanodots that down-regulate ROS in zebrafish

Oxidative damage induced by accumulation of excessive reactive oxygen species (ROS) could result in increased chronic inflammation and thus ageing and age-related diseases. Carbonaceous nanodrugs hold great promise for ameliorating age-related diseases, and it is necessary to develop ultrahigh-yield synthesis of such nanodrugs. To improve the synthetic yield (less than 50%) of carbon nanodots (CNDs), the general choice is to screen precursors. However, no reliable concept for improving the yield has been explored over the past few decades. We are the first to propose the concept of using carbon-carbon double bonds to boost the synthetic yield and demonstrate record breaking ultrahigh-yield (85.9%) synthesis of N-doped CNDs. When the C[double bond, length as m-dash]C content increased from 14 to 56 mmol, the synthetic yield exhibited a 3.3-fold increase. Nitrogen elements are doped as pyridinic-like N and NH₂, where conjugated π-systems as electron donors and pyridinic-like structures would benefit the potential down-regulated effect for ROS. N-doped CNDs exhibit an outstanding protective effect against oxidative stress via inhibiting exogenous and endogenous ROS generation, where the ROS in zebrafish are significantly reduced by 68%. Hence the concept of carbon-carbon double bond-boosted ultrahigh-yield synthesis of N-doped CNDs provides a promising strategy to be employed for carbonaceous nanodrugs aiming at preventing and curing ageing and age-related diseases.

Fullerenol nanoparticles decrease ischaemia-induced brain injury and oedema through inhibition of oxidative damage and aquaporin-1 expression in ischaemic stroke

BACKGROUND

We examined the possible protective effects of fullerenol nanoparticles on brain injuries and oedema in experimental model of ischaemic stroke through inhibition of oxidative damage and aquaporin-1 (AQP-1) expression.

METHODS

Experiment was done in three groups of rats (N = 66): sham, control ischaemia and ischaemic treatment. Ischaemia was induced by 90-minutes middle cerebral artery occlusion (MCAO) followed by 24 hours of reperfusion. Rats received a dose of 10 mg/kg of fullerenol 30 minutes before MCAO. Infarction, brain oedema, malondialdehyde (MDA) and nitrate contents as well as mRNA level of AQP-1 were determined 24 hours after termination of MCAO.

RESULTS

Administration of fullerenol before MCAO significantly reduced the infarction of cortex and striatum by 72 and 77%, respectively. MCAO induced brain oedema in control ischaemic rats (3.83 ± 0.53%), whereas, fullerenol significantly reduced it (0.91 ± 0.55%). The contents of MDA and nitrate increased in ischaemic hemispheres by 86 and 41%, respectively. Fullerenol considerably reduced the MDA and nitrate contents by 83 and 48%, respectively. Moreover, MCAO noticeably increased the mRNA level of AQP-1 in ischaemic hemispheres by 22%, whereas fullerenol significantly decreased it by 29%.

DISCUSSION

Fullerenol is able to reduce ischaemia-induced brain injuries and oedema possibly through inhibition of oxidative damage and AQP-1 expression in ischaemic stroke.

Gd@C82-(ethylenediamine)8 Nanoparticle: A New High-Efficiency Water-Soluble ROS Scavenger

It is important to maintain a reactive oxygen species (ROS) balance in organisms; thus, a valid ROS scavenger with good biocompatibility is urgently required. To prepare a high-efficiency ROS scavenger, multiple ethylenediamine (EDA) groups are bonded for the first time to a metallofullerene Gd@C₈₂ to obtain water-soluble Gd@C₈₂-(EDA)₈ nanoparticles (NPs) through a facile solid-liquid reaction. Gd@C₈₂-(EDA)₈ NPs with a relatively better conjugation possess an excellent capability to scavenge hydroxyl radicals. Moreover, Gd@C₈₂-(EDA)₈ NPs exhibited a remarkable cytoprotective effect against H₂O₂-induced injuries to human epidermal keratinocytes-adult (HEK-a) cells at a low concentration of 2.5 μM. In contrast, Gd@C₈₂-(OH)₂₆ NPs that modified with hydroxyls show an apparent protective effect at a much higher concentration of 40 μM. This outstanding cytoprotective performance of Gd@C₈₂-(EDA)₈ NPs is mainly attributed to their extremely high cellular uptake and comparably strong conjugation. Gd@C₈₂-(EDA)₈ NPs with good biocompatibility exhibit excellent ROS scavenging capability even at a significantly low concentration, which promotes its versatile applications in cosmetics and biomedicine.

Functionalized Fullerene Increases NF-κB Activity and Blocks Genotoxic Effect of Oxidative Stress in Serum-Starving Human Embryo Lung Diploid Fibroblasts

The influence of a water-soluble [60] fullerene derivative containing five residues of 3-phenylpropionic acid and a chlorine addend appended to the carbon cage (F-828) on serum-starving human embryo lung diploid fibroblasts (HELFs) was studied. Serum deprivation evokes oxidative stress in HELFs. Cultivation of serum-starving HELFs in the presence of 0.1–1 µM F-828 significantly decreases the level of free radicals, inhibits autophagy, and represses expression of NOX4 and NRF2 proteins. The activity of NF-κB substantially grows up in contrast to the suppressed NRF2 activity. In the presence of 0.2–0.25 µM F-828, the DSB rate and apoptosis level dramatically decrease. The maximum increase of proliferative activity of the HELFs and maximum activity of NF-κB are observed at these concentration values. Conclusion. Under the conditions of oxidative stress evoked by serum deprivation the water-soluble fullerene derivative F-828 used in concentrations of 0.1 to 1 µM strongly stimulates the NF-κB activity and represses the NRF2 activity in HELFs.

Polyhydroxylated fullerene nanoparticles attenuate brain infarction and oxidative stress in rat model of ischemic stroke

Oxidative stress is the common underlying mechanism of damage in ischemic stroke. Therefore, we aimed to evaluate the possible protective effects of polyhydroxylated fullerene derivatives on brain infarction and oxidative/nitrosative stress in a rat model of ischemic stroke. The experiment was performed by four groups of rats (each; n=12); Sham, Control ischemia, and ischemic treatment groups (Pretreatment and Posttreatment). Brain ischemia was induced by 90 min middle cerebral artery occlusion (MCAO) followed by 24 hours reperfusion. Rats received fullerene nanoparticles at dose of 1 mg/kg 30 min before MCAO and immediately after beginning of reperfusion. Infarct volume, contents of malondialdehyde (MDA), glutathione (GSH) and nitrate as well as superoxide dismutase (SOD) activity were assessed 24 hours after termination of MCAO. Brain infarct volume was 310 ± 21 mm³ in control group. Administration of fullerene nanoparticles before and after MCAO significantly decreased the infarct volume by 53 % (145 ± 45 mm³) and 81 % (59 ± 13 mm³), respectively. Ischemia also enhanced MDA and nitrate contents of ischemic hemispheres by 45 % and 25 % , respectively. Fullerene nanoparticles considerably reduced the MDA and nitrate contents of ischemic hemispheres before MCAO by 58 % and 17 % , respectively, and after MCAO by 38 % and 21 % , respectively. Induction of MCAO significantly decreased GSH content (19 % ) and SOD activity (52 % ) of ischemic hemispheres, whereas fullerene nanoparticles increased the GSH content and SOD activity of ischemic hemispheres by 19 % and 52 % before MCAO, respectively, and 21 % and 55 % after MCAO, respectively. Our findings indicate that fullerene nanoparticles, as a potent scavenger of free radicals, protect the brain cells against ischemia/reperfusion injury and inhibit brain oxidative/nitrosative damage.

Carboxylic Acid Fullerene (C60) Derivatives Attenuated Neuroinflammatory Responses by Modulating Mitochondrial Dynamics

Fullerene (C60) derivatives, a unique class of compounds with potent antioxidant properties, have been reported to exert a wide variety of biological activities including neuroprotective properties. Mitochondrial dynamics are an important constituent of cellular quality control and function, and an imbalance of the dynamics eventually leads to mitochondria disruption and cell dysfunctions. This study aimed to assess the effects of carboxylic acid C60 derivatives (C60-COOH) on mitochondrial dynamics and elucidate its associated mechanisms in lipopolysaccharide (LPS)-stimulated BV-2 microglial cell model. Using a cell-based functional screening system labeled with DsRed2-mito in BV-2 cells, we showed that LPS stimulation led to excessive mitochondrial fission, increased mitochondrial localization of dynamin-related protein 1 (Drp1), both of which were markedly suppressed by C60-COOH pretreatment. LPS-induced mitochondria reactive oxygen species (ROS) generation and collapse of mitochondrial membrane potential (ΔΨm) were also significantly inhibited by C60-COOH. Moreover, we also found that C60-COOH pretreatment resulted in the attenuation of LPS-mediated activation of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) signaling, as well as the production of pro-inflammatory mediators. Taken together, these findings demonstrated that carboxylic acid C60 derivatives may exert neuroprotective effects through regulating mitochondrial dynamics and functions in microglial cells, thus providing novel insights into the mechanisms of the neuroprotective properties of carboxylic acid C60 derivatives.

Effect of surfactants on the removal and acute toxicity of aqueous nC60 aggregates in water treatment process

This work aimed to evaluate the effect of surfactants on the removal of aqueous nC60 aggregates by coagulation-filtration process and assess the acute toxicity of filtrates by Microtox test. Three surfactants including cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100 (TX100) were selected representing cationic, anionic, and nonionic types, respectively. Results showed that the change of physicochemical properties of nC60 associating with different types of surfactants determined nC60's removal efficiency and acute toxicity. CTAB increased the number of large particles. It also changed the zeta potential of nC60 from negative to positive, leading to the low removal rates (17.3-50.2%) when CTAB concentration was designed in the range of 0.03-1 g/L, and the filtrates showed acute toxicity to bioluminescent bacteria (inhibition rate > 80%). On the contrary, TX100 obviously increased the proportion of small particles, and it is noteworthy that even less than 1 mg/L of nC60 (20% of the initial concentration) with TX100 remaining in filtrates could evoke phototoxicity due to reactive oxygen species (ROS) generation under UV irradiation. Compared to CTAB and TX100, SDS exerted an effect on the removal process and toxicity of nC60 only when concentration was beyond the critical micelle concentration (CMC; 2.5 g/L). These findings collectively suggest that characteristics of nC60 are flexible and strongly dependent on surfactant modification, as a result of which these particles could potentially find their way through water treatment route and exert a potential toxicity risk.

PVP formulated fullerene (C60) increases Rho-kinase dependent vascular tissue contractility in pregnant Sprague Dawley rats

Pregnancy is a unique physiological state, in which C60 fullerene is reported to be distributed in both maternal and fetal tissues. Tissue distribution of C60 differs between pregnant and non-pregnant states, presumably due to functional changes in vasculature during pregnancy. We hypothesized that polyvinylpyrrolidone (PVP) formulated C60 (C60/PVP) increases vascular tissue contractility during pregnancy by increasing Rho-kinase activity. C60/PVP was administered intravenously to pregnant and non-pregnant female Sprague Dawley rats. Vascular responses were assessed using wire myography 24h post-exposure. Increased stress generation was observed in uterine artery, thoracic aorta and umbilical vein. Rho-Rho-kinase mediated force maintenance was increased in arterial segments from C60/PVP exposed pregnant rats when compared to PVP exposed rats. Our findings suggest that intravenous exposure to C60/PVP during pregnancy increases vascular tissue contractility of the uterine artery through elements of Rho-Rho-kinase signaling during late stages of pregnancy.

Polyhydroxylated fullerene attenuates oxidative stress-induced apoptosis via a fortifying Nrf2-regulated cellular antioxidant defence system

Polyhydroxylated derivatives of fullerene C60, named fullerenols (C60[OH]n), have stimulated great interest because of their potent antioxidant properties in various chemical and biological systems, which enable them to be used as a new promising pharmaceutical for the future treatment of oxidative stress-related diseases, but the details remain unknown. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a principal transcription factor that regulates expression of several antioxidant genes via binding to the antioxidant response element and plays a crucial role in cellular defence against oxidative stress. In this study we investigated whether activation of the Nrf2/antioxidant response element pathway contributes to the cytoprotective effects of C60(OH)24. Our results showed that C60(OH)24 enhanced nuclear translocation of Nrf2 and upregulated expression of phase II antioxidant enzymes, including heme oxygenase-1 (HO-1), NAD(P)H: quinine oxidoreductase 1, and γ-glutamate cysteine ligase in A549 cells. Treatment with C60(OH)24 resulted in phosphorylation of p38 mitogen-activated protein kinases (p38 MAPK), extracellular signal-regulated kinases, and c-Jun-N-terminal kinases. By using inhibitors of cellular kinases, we showed that pretreatment of A549 cells with SB203580, a specific inhibitor of p38 MAPK, abolished nuclear translocation of Nrf2 and induction of HO-1 protein induced by C60(OH)24, indicating an involvement of p38 MAPK in Nrf2/HO-1 activation by C 60(OH)24. Furthermore, pretreatment with C60(OH)24 attenuated hydrogen peroxide-induced apoptotic cell death in A549 cells, and knockdown of Nrf2 by small interfering ribonucleic acid diminished C60(OH)24-mediated cytoprotection. Taken together, these findings demonstrate that C60(OH)24 may attenuate oxidative stress-induced apoptosis via augmentation of Nrf2-regulated cellular antioxidant capacity, thus providing insights into the mechanisms of the antioxidant properties of C60(OH)24.

C70-carboxyfullerenes as efficient antioxidants to protect cells against oxidative-induced stress

Oxidative stress induced by excessive production of reactive oxygen species (ROS) has been implicated in the etiology of many human diseases. Acquiring a highly efficient antioxidant with good biocompatibility is of significance in eliminating the deleterious effect induced by the oxidative stress. Herein, we address our efforts on investigating the cytoprotective effect of carboxyfullerenes on H2O2-injured cells. Meanwhile, the uptake and intracellular location of carboxyfullerenes were studied. The results show that C70-carboxyfullerenes (dimalonic acid C70 fullerene (DF70) and trimalonic acid C70 fullerene (TF70)) exhibit an obviously protective effect against oxidative stress on C2C12 cells at concentrations as low as 2.5 μmol L(-1), whereas C60-carboxyfullerenes (dimalonic acid C60 fullerene (DF60) and quadri-malonic acid C60 fullerene (QF60)) show a protective effect at relatively higher concentration (40 μmol L(-1)). The molecular structure of carboxyfullerenes and the physiological state of cells play an important role in the different cytoprotective capability. Further study reveals that DF70 and TF70 could enter into cells and mainly localize into the lysosome, which possibly involves the protective mechanism by stabilizing lysosome. The use of a significantly low concentration of C70-carboxyfullerene as the antioxidative agent will benefit the therapeutic approaches aiming at alleviating ROS-induced injuries such as muscle disorder and arthritis.

Protective effect of C70-carboxyfullerene against oxidative-induced stress on postmitotic muscle cells

Satellite muscle cells play an important role in regeneration of skeletal muscle. However, they are particularly vulnerable to oxidative stress. Herein, we address our efforts on the cytoprotective activities of carboxyfullerenes with different cage size (C60 vs C70) and adduct number on postmitotic muscle cell (C2C12 cell). The correlation of the structural effect on the cytoprotective capability of carboxyfullerenes was evaluated. We find that quadri-malonic acid C70 fullerene (QF70) exhibits higher capability on protecting cells from oxidative-induced stress among these tested carboxyfullerenes. The accumulation of intracellular superoxide dismutase (SOD) is proposed to play an important role in their diverse antioxidative ability. Moreover, the pretreatment of QF70 could also obviously enhance the viability of myotubes originated from oxidative-stressed C2C12 cells, which facilitates the future application of carboxyfullerenes in tissue engineering and nanomedicine.

Protection of cells from nitric oxide-mediated apoptotic death by glutathione C₆₀ derivative

The influence of the glutathione C₆₀ derivative on the cytotoxicity of a highly reactive free radical NO (nitric oxide) has been investigated. Consistent with its cytoprotective abilities, the derivative scavenges ROS (reactive oxygen species) and RNS (reactive nitrogen species) both in vitro and under cell-free conditions. Moreover, the glutathione C₆₀ derivative protected PC12 cells from the cytotoxic effect of the NO-releasing compound, SNP (sodium nitroprusside). Addition of glutathione C₆₀ derivative alone did not induce apoptosis and necrosis. The results suggest that the glutathione C₆₀ derivative has the potential to prevent NO-mediated cell death without evident toxicity.

Neuronal uptake and intracellular superoxide scavenging of a fullerene (C60)-poly(2-oxazoline)s nanoformulation

Fullerene, the third allotrope of carbon, has been referred to as a "radical sponge" because of its powerful radical scavenging activities. However, the hydrophobicity and toxicity associated with fullerene limits its application as a therapeutic antioxidant. In the present study, we sought to overcome these limitations by generating water-soluble nanoformulations of fullerene (C(60)). Fullerene (C(60)) was formulated with poly(N-vinyl pyrrolidine) (PVP) or poly(2-alkyl-2-oxazoline)s (POx) homopolymer and random copolymer to form nano-complexes. These C(60)-polymer complexes were characterized by UV-vis spectroscopy, infrared spectroscopy (IR), dynamic light scattering (DLS), atomic force microscopy (AFM) and transmission electron microscopy (TEM). Cellular uptake and intracellular distribution of the selected formulations in catecholaminergic (CATH.a) neurons were examined by UV-vis spectroscopy, immunofluorescence and immunogold labeling. Electron paramagnetic resonance (EPR) spectroscopy was used to determine the ability of these C(60)-polymer complexes to scavenge superoxide. Their cytotoxicity was evaluated in three different cell lines. C(60)-POx and C(60)-PVP complexes exhibited similar physicochemical properties and antioxidant activities. C(60)-poly(2-ethyl-2-oxazoline) (PEtOx) complex, but not C(60)-PVP complex, were efficiently taken up by CATH.a neurons and attenuated the increase in intra-neuronal superoxide induced by angiotensin II (Ang II) stimulation. These results show that C(60)-POx complexes are non-toxic, neuronal cell permeable, superoxide scavenging antioxidants that might be promising candidates for the treatment of brain-related diseases associated with increased levels of superoxide.

Oxidative stress-mediated hemolytic activity of solvent exchange-prepared fullerene (C60) nanoparticles

The present study investigated the hemolytic properties of fullerene (C(60)) nanoparticles prepared by solvent exchange using tetrahydrofuran (nC(60)THF), or by mechanochemically assisted complexation with macrocyclic oligosaccharide gamma-cyclodextrin (nC(60)CDX) or the copolymer ethylene vinyl acetate-ethylene vinyl versatate (nC(60)EVA-EVV). The spectrophotometrical analysis of hemoglobin release revealed that only nC(60)THF, but not nC(60)CDX or nC(60)EVA-EVV, was able to cause lysis of human erythrocytes in a dose- and time-dependent manner. Atomic force microscopy revealed that nC(60)THF-mediated hemolysis was preceded by erythrocyte shrinkage and increase in cell surface roughness. A flow cytometric analysis confirmed a decrease in erythrocyte size and demonstrated a significant increase in reactive oxygen species production in red blood cells exposed to nC(60)THF. The nC(60)THF-triggered hemolytic activity was efficiently reduced by the antioxidants N-acetylcysteine and butylated hydroxyanisole, as well as by serum albumin, the most abundant protein in human blood plasma. These data indicate that nC(60)THF can cause serum albumin-preventable hemolysis through oxidative stress-mediated damage of the erythrocyte membrane.

The protective activities of water-soluble C(60) derivatives against nitric oxide-induced cytotoxicity in rat pheochromocytoma cells

In this study, the protective activities of water-soluble C(60) derivatives against nitric oxide (NO) induced cytotoxicity were investigated. To overcome C(60) insolubility in water, we modified C(60) with β-alanine, valine or folacin. The compounds were characterized by FT-IR, (1)H NMR, (13)C NMR, LC-MS, elemental analysis, light scattering and TEM. Investigation of the possible NO-scavenging activities of water-soluble C(60) derivatives demonstrated that they expressed direct scavenging activity toward NO liberated within solution of sodium nitroprusside (SNP). In parallel, following exposure of cells to SNP (1 mM), a marked decrease in mitochondrial membrane potential, cell viability, activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), as well as increased levels of intracellular NO accumulation and malondialdehyde (MDA) production were observed. Moreover, SNP caused significant elevation in intracellular caspase-3 activity, and induced apoptotic death as determined by flow cytometric assay. However, pretreatment of the cells with water-soluble C(60) derivatives prior to SNP exposure blocked these NO-induced cellular events noticeably. Experiments demonstrated that the aggregation morphology could impact the NO-scavenging abilities and protective effects on apoptosis of water-soluble C(60) derivatives. The results suggest that water-soluble C(60) derivatives have the potential to prevent NO-mediated cell death without evident toxicity.

The effect of squalane-dissolved fullerene-C60 on adipogenesis-accompanied oxidative stress and macrophage activation in a preadipocyte-monocyte co-culture system

Effects of squalane-dissolved fullerene-C60 (Sql-fullerene) on macrophage activation and adipose conversion with oxidative stress were studied using an inflammatory adipose-tissue equivalent (ATE) and OP9 mouse stromal preadipocyte-U937 lymphoma cell co-culture systems. Differentiation of OP9 cells was initiated by insulin-rich serum replacement (SR) as an adipogenic stimulant, and then followed by accumulation of intracellular lipid droplets and reactive oxygen species (ROS), both of which were significantly inhibited by Sql-fullerene. In the OP9-U937 cell co-culture system, U937 cells rapidly differentiated to macrophage-like cells during SR-induced adipogenesis in OP9 cells. The ROS accumulation was in the co-culture more marked than in OP9 cells alone, suggesting that the interaction between adipocytes and monocytes/macrophages promotes inflammatory responses. Sql-fullerene significantly inhibited macrophage activation and low-grade adipogenesis in the OP9-U937 co-culture system. We developed a three-dimensional inflammatory adipose-tissue model "ATE" consisting of, characteristically, U937 cells in the culture-wells, and, in addition, mounted a culture insert containing OP9 cells-populated collagen gel. ATE is enabled with suitable stimulation to represent the pathology of inflammatory disorders, such as macrophage infiltration in adipose tissue. Five-day culturing of ATE in SR medium occurred U937 macrophage migration and intracellular oil-droplet accumulation that were significantly inhibited by Sql-fullerene. Our results suggest that Sql-fullerene might be explored as a potential medicine for the treatment of metabolic syndrome or other obesity-related disorders.