Interactions of polydispersed single-walled carbon nanotubes with T cells resulting in downregulation of allogeneic CTL responsesin vitroandin vivo

Carboxyl nanodiamonds inhibit melanoma tumor metastases by blocking cellular motility and invasiveness

Carboxyl nanodiamond (cND) nanoparticles are actively internalized by B16F10 melanoma cells in culture. Treatment of B16F10 tumor cells with cNDs in vitro inhibited their ability to (i) migrate and invade through porous membranes in a transwell culture system, (ii) secrete matrix metalloproteinases (MMPs) MMP-2 and MMP-9, and (iii) express selected epithelial-mesenchymal transition markers critical for cell migration and invasion. Administration of luciferase-transfected B16F10-Luc2 melanoma cells resulted in a rapid growth of the tumor and its metastasis to different organs that could be monitored by in vivo bioluminescence imaging as well as by ex vivo BLI of the mouse organs. After tumor cells were administered intravenously in C57Bl/6 mice, administration of cNDs (50 μg i.v. every alternate day) resulted in marked suppression of the tumor growth and metastasis in different organs of mice. Subcutaneous administration of B16F10 cells resulted in robust growth of the primary tumor subcutaneously as well as its metastasis to the lungs, liver, spleen, and kidneys. Intravenous treatment with cNDs did not affect the growth of the primary tumor mass but essentially blocked the metastasis of the tumor to different organs. Histological examination of mouse organs indicated that the administration of cNDs by itself was safe and did not cause toxic changes in mouse organs. These results indicate that the cND treatment may have an antimetastatic effect on the spread of B16F10 melanoma tumor cells in mice. Further exploration of cNDs as a possible antimetastatic therapeutic agent is suggested.

Toxicity of poly-dispersed single-walled carbon nanotubes on bone marrow derived Hematopoietic Stem and Progenitor Cells

This study has explored the effect of acid-functionalized single-walled carbon nanotubes (AF-SWCNTs) on Hematopoietic Stem and Progenitor Cell (HSPCs) in mouse bone marrow. Administration of AF-SWCNTs induced a significant decline in the live-cell recovery from bone marrow. Lin-negative Stem cell enriched HSPCs internalized AF-SWCNTs that remained localized in cytoplasmic areas. Incubation of HSPCs with AF-SWCNTs resulted in induction of cell death, inhibition of cell cycle, and induction of reactive oxygen species (ROS) as well as the expression of Caspase 3, 7 and 9 enzymes. In vitro culture with a cytokine cocktail (SCF, GM-CSF, IL3, IL6, IL7) induced differentiation of HSPCs into lymphocytes and myeloid cells, that was inhibited in presence of AF-SWCNTs. Relative recoveries of lymphocytes specifically B lymphocytes, was significantly reduced by AF-SWCNT-treatment, whereas the relative recovery of myeloid cells remained unaltered. These results suggest that AF-SWCNTs have significant toxic effects on HSPCs and differentially suppress the ontogeny of lymphoid and myeloid cells.

Poly-dispersed Acid-Functionalized Single-Walled Carbon Nanotubes (AF-SWCNTs) Are Potent Inhibitor of BCG Induced Inflammatory Response in Macrophages

The present study is focused on the modulation of Mycobacterium bovis BCG-induced inflammatory response by poly-dispersed acid-functionalized single-walled carbon nanotubes (AF-SWCNTs) in macrophages. Flow cytometric and confocal microscopy studies indicated that both BCG and AF-SWCNTs were efficiently internalized by RAW 264.7 and MH-S macrophage cell lines and were essentially localized in the cytoplasmic area. BCG-induced production of reactive oxygen species (ROS) and nitric oxide by the two cell lines was significantly inhibited by AF-SWCNTs. Using RT-PCR technique, a marked decline was observed in the expression of BCG-induced pro-inflammatory genes COX-2, iNOS, TNF-α, IL-6, and IL-1β upon treatment with AF-SWCNTs. Results of gelatin zymography indicated that the AF-SWCNTs treatment also induced a marked decline in BCG-induced release of matrix metalloproteinases MMP-2 and MMP-9 by the two macrophage cell lines. The anti-inflammatory effect of AF-SWCNTs in downregulating BCG-induced inflammatory response was further validated in murine peritoneal macrophages. Treatment with AF-SWCNTs led to a steep decline in BCG-induced NO production in murine peritoneal macrophages in vitro as well as in vivo. Peritoneal macrophages isolated from mice treated with BCG and AF-SWCNTs had a significantly lower intracellular expression of COX-2 as compared to the peritoneal macrophages derived from mice treated with BCG alone. Taken together, our results demonstrate a potent anti-inflammatory effect of AF-SWCNTs in alleviating BCG-induced inflammatory responses in macrophages in vitro and in vivo.

Poly dispersed acid-functionalized single walled carbon nanotubes target activated T and B cells to suppress acute and chronic GVHD in mouse model

Graft versus host disease (GVHD) results from hyper-activation of transplanted lymphocytes against the host antigens. Bone marrow transplantation in humans as well as some cases of blood transfusion and organ transplantation are associated with a strong GVH reaction resulting in GVHD that in many cases may be fatal. We had previously shown that poly-dispersed acid-functionalized single-walled carbon nanotubes (AF-SWCNTs) specifically target activated T and B lymphocytes and kill them. In the present study, efficacy of AF-SWCNTs to suppress the GVH reaction was tested in the mouse model. Acute GVHD was induced in mice by administering intravenously 30 or 60 million spleen cells from a parental strain (C57bl/6 mouse, MHC haplotype H-2^b) to host (C57bl/6 x Balb/c) F1 mice (MHC haplotype H-2^b/d)and waiting for 8-10 days. Chronic GVHD was similarly induced by administration of 30 million parent spleen cells to F1 mice and waiting for a period of 60 days. Our results demonstrate a marked decline in splenomegaly and recovery of spleen T (both CD4 and CD8) and B cells in GVHD mice treated with AF-SWCNTs. AF-SWCNTs treatment also limited T and B cell proliferation by restricting S-phage of cell cycle. Generation of anti-host cytotoxic T cells (CTLs) was also markedly suppressed by AF-SWCNT treatment of acute GVHD mice, and a significant reduction in the generation of anti-host antibodies could also be demonstrated. Taken together, our results suggest that the AF-SWCNTs can be considered as a potential therapeutic agent for treating GVHD.

Mast Cells May Differentially Regulate Growth of Lymphoid Neoplasms by Opposite Modulation of Histamine Receptors

Cancer microenvironment is complex and consists of various immune cells. There is evidence for mast cell (MC) infiltration of tumors, but their role thereof is poorly understood. In this study, we explored the effects of mast cell and their mediators on the growth of hematological cancer cells. The affect is demonstrated using RBL-2H3 MCs, and YAC-1, EL4 and L1210 as hematological cancer cell lines. Direct contact with MCs or stimulation by their mediators caused growth inhibition of YAC-1 cells, growth enhancement of EL4 cells and no change in growth of L1210 cells. This effect was confirmed by cancer cell recovery, cell viability, mitochondrial health, and cell cycle analysis. MCs showed mediator release in direct contact with tumor cells. MC mediators' treatment to YAC-1 and EL4 yielded exactly opposite modulations of survival markers, Survivin and COX-2 and apoptosis markers, Caspase-3, Bcl-2, in the two cell lines. Histamine being an important MC mediator, effect of histamine on cell recovery, survival markers and expression of various histamine receptors and their modulation in cancer cells was studied. Again, YAC-1 and EL4 cells showed contrary histamine receptor expression modulation in response to MC mediators. Histamine receptor antagonist co-treatment with MC mediators to the cancer cells suggested a major involvement of H2 and H4 receptor in growth inhibition in YAC-1 cells, and contribution of H1, H2, and H4 receptors in cell growth enhancement in EL4 cells. L1210 showed changes in the histamine receptors' expression but no effect on treatment with receptor antagonists. It can be concluded that anti-cancerous action of MCs or their mediators may include direct growth inhibition, but their role may differ depending on the tumor.

Elevated internalization and cytotoxicity of polydispersed single-walled carbon nanotubes in activated B cells can be basis for preferential depletion of activated B cells in vivo

Uptake of polydispersed acid-functionalized single-walled carbon nanotubes (AF-SWCNTs) in resting and LPS-activated B cells was studied using fluorescence-tagged AF-SWCNTs (FAF-SWCNTs). Activated B cells internalized substantially higher amounts of FAF-SWCNTs [76.5% AF-SWCNT⁺ B cells, mean fluorescence intensity (MFI) 720.6] as compared to the resting B cells [39.5% AF-SWCNT⁺ B cells, MFI 198.5]. B cells in S and G2/M phases were found to have significantly higher uptake of FAF-SWCNTs as compared to cells in G0/G1 phase. Confocal microscopy indicated that AF-SWCNTs were essentially localized on cell membrane in resting B cells, whereas in activated B cells, AF-SWCNTs were distributed throughout the cytoplasm. Targeting of AF-SWCNTs specifically to activated B cells in vivo was examined by first administering intravenously LPS-activated B cells tagged with fluorescence tracer (CFSE) in mice, followed by FAF-SWCNTs through the same route. It was found that FAF-SWCNTs were specifically taken up by CFSE+CD19+-activated B cells (95% FAF-SWCNT⁺ B cells, MFI 3725) as compared to CFSE^- CD19⁺ resting B cells (31.1% FAF-SWCNT⁺ B cells, MFI 428). Administration (i.v.) of LPS resulted in a significant increase in the proportion of B cell in mouse spleen that was reduced by 68% by administering AF-SWCNTs. In control mice, the corresponding decrease in B cell proportion was 49%, which was significantly lower (p < 0.005) than the decline in LPS-treated mice. These results indicate that AF-SWCNTs may have the potential as an agent for depleting activated B cells in vivo.

Uptake of poly-dispersed single-walled carbon nanotubes and decline of functions in mouse NK cells undergoing activation

The interaction of poly-dispersed acid-functionalized single-walled carbon nanotubes (AF-SWCNT) with NK cells undergoing activation was examined. Exposure to AF-SWCNT during NK activation in vitro by interleukin (IL)-2, and in vivo by Poly(I:C) significantly lowered cytotoxic activity generated against YAC-1 tumor cells. Recoveries of spleen NK1.1(+) cells as well as the activated subset of NK cells (NK1.1(+)CD69(+) cells) were significantly reduced by the AF-SWCNT exposure. The proportion of apoptotic NK cells (NK1.1(+) phosphatidylserine(+)) in the spleen cell preparations activated in vitro was also significantly elevated. Expression levels of CD107a [for assessing NK cell degranulation] as well as of FasL marker [mediating non-secretory pathway of NK cell killing] were significantly lower in cells exposed to AF-SWCNT during the activation phase. Intracellular levels of interferon (IFN)-γ and tumor necrosis factor (TNF)-α in the cells were also significantly reduced. Fluorescent AF-SWCNT (FAF-SWCNT) were internalized by the NK cells and uptake was significantly greater in activated cells. Confocal microscopy indicated the internalized FAF-SWCNT were localized to the cytoplasm of the NK cells. These results indicated that AF-SWCNT were internalized by NK cells and caused a general down-regulation of a variety of parameters associated with NK cell cytotoxicity and other cellular functions.

Selective nuclear localization of siRNA by metallic versus semiconducting single wall carbon nanotubes in keratinocytes

BACKGROUND

The potential use of carbon nanotubes (CNTs) in gene therapy as delivery systems for nucleic acids has been recently recognized. Here, we describe that metallic versus semiconducting single-wall CNTs can produce significant differences in transfection rate and cellular distribution of siRNA in murine PAM212 keratinocytes.

RESULTS/METHODOLOGY

The results of cell interaction studies, coupled with supportive computational simulations and ultrastructural studies revealed that the use of metallic single wall CNTs resulted in siRNA delivery into both the cytoplasm and nucleus of keratinocytes, whereas semiconducting CNTs resulted in delivery only to the cytoplasm.

CONCLUSION

Using enriched fractions of metallic or semiconducting CNTs for siRNA complex preparation may provide specific subcellular targeting advantages.

Hepatic oxidative stress and catalyst metals accumulation in goldfish exposed to carbon nanotubes under different pH levels

Experiments were conducted to investigate the effect of three different carbon nanotubes [single-walled carbon nanotubes (SWCNTs), hydroxylated multi-walled carbon nanotubes (OH-MWCNTs), and carboxylated multi-walled carbon nanotubes (COOH-MWCNTs)] on antioxidant parameters and metals accumulation in the liver of Carassius auratus. A semi-static test system was used to expose C. auratus to either a freshwater control, 0.1, or 0.5mg/L CNTs at three pH levels (5.0, 7.25, and 9.0) for 3 and 12 days. The activities of three antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), together with the level of glutathione (GSH) and malondialdehyde (MDA) were determined in liver on the 3rd and 12th day. The results showed that there was a significant increase in MDA concentration and SOD activity in fish exposed to CNTs, indicating that CNTs exposure induces an oxidative stress response in fish. According to integrated biomarker response (IBR) index, the effect of these three CNTs on liver can be ordered as SWCNTs>OH-MWCNTs>COOH-MWCNTs and they are more toxic to fish in an alkaline environment. Moreover, the concentrations of catalyst metals (Co, Ni, and Mo) and bioelements (Cu, Fe, Zn, and Se) in liver were changed, depending on the CNTs concentration, the pH level, and the exposure duration. Generally, all CNTs groups showed that catalyst metals could be concentrated significantly into the liver of fish, and changes in hepatic Cu, Zn, Fe, and Se contents are consistent with the activity of antioxidant enzymes.

Lipid antigen presentation through CD1d pathway in mouse lung epithelial cells, macrophages and dendritic cells and its suppression by poly-dispersed single-walled carbon nanotubes

Effect of poly-dispersed acid-functionalized single-walled carbon nanotubes (AF-SWCNTs) was examined on lipid antigen presentation through CD1d pathway on three cell lines, LA4, MHS, and JAWSII used as prototype antigen presenting cells (APCs). CD1d molecule was expressed on 80-90% MHS (prototype macrophages) and JAWSII (prototype dendritic cells) cells whereas <5% LA4 cells (lung epithelial cells, non-classical APCs) expressed CD1d. Treatment with AF-SWCNTs but not with pristine SWCNTs resulted in a significant decline in the level of CD1d mRNA as well as mRNA levels of some other intracellular proteins involved in lipid antigen presentation pathway (MTP, ApoE, prosaposin, SR-BI and LDLr). Lipid antigen presentation was assessed by first incubating the cells with a prototype lipid antigen (α-Glactosylceramide or αGC) and then staining with L363 monoclonal antibody that detects αGC bound to CD1d molecule. While 100% MHS and JAWSII cells presented αGC, only 20% LA4 cells presented the CD1d antigen. Treatment with AF-SWCNTs resulted in a 30-40% decrease in αGC antigen presentation in all three cell lines. These results show that AF-SWCNT treatment down regulated the lipid antigen presentation pathway in all three cell lines and significantly lowered the ability of these cell lines to present αGC antigen.

When carbon nanotubes encounter the immune system: desirable and undesirable effects

The role of our immune system is to bring efficient protection against invasion by foreign elements, not only pathogens but also any material it may be in contact with. Nanoparticles may enter the body and encounter the immune system either intentionally (e.g. administration for biomedical application) or not (e.g. respiratory occupational exposure). Therefore, it is of fundamental importance to get a thorough knowledge of the way they interact with immune cells and all related consequences. Among nanomaterials, carbon nanotubes (CNTs) are of special interest because of their tremendous field of applications. Consequently, their increasing production, processing and eventual incorporation into new types of composites and/or into biological systems have raised fundamental issues regarding their potential impact on health. This review aims at giving an overview of the known desirable and undesirable effects of CNTs on the immune system, i.e. beneficial modulation of immune cells by CNTs engineered for biomedical applications versus toxicity, inflammation and unwanted immune reactions triggered by CNTs themselves.