Inhibition of inflammatory arthritis using fullerene nanomaterials.

Inflammatory arthritis (e.g. rheumatoid arthritis; RA) is a complex disease driven by the interplay of multiple cellular lineages. Fullerene derivatives have previously been shown to have anti-inflammatory capabilities mediated, in part, by their ability to prevent inflammatory mediator release by mast cells (MC). Recognizing that MC can serve as a cellular link between autoantibodies, soluble mediators, and other effector populations in inflammatory arthritis, it was hypothesized that fullerene derivatives might be used to target this inflammatory disease. A panel of fullerene derivatives was tested for their ability to affect the function of human skin-derived MC as well as other lineages implicated in arthritis, synovial fibroblasts and osteoclasts. It is shown that certain fullerene derivatives blocked FcγR- and TNF-α-induced mediator release from MC; TNF-α-induced mediator release from RA synovial fibroblasts; and maturation of human osteoclasts. MC inhibition by fullerene derivatives was mediated through the reduction of mitochondrial membrane potential and FcγR-mediated increases in cellular reactive oxygen species and NF-κB activation. Based on these in vitro data, two fullerene derivatives (ALM and TGA) were selected for in vivo studies using K/BxN serum transfer arthritis in C57BL/6 mice and collagen-induced arthritis (CIA) in DBA/1 mice. Dye-conjugated fullerenes confirmed localization to affected joints in arthritic animals but not in healthy controls. In the K/BxN moldel, fullerenes attenuated arthritis, an effect accompanied by reduced histologic inflammation, cartilage/bone erosion, and serum levels of TNF-α. Fullerenes remained capable of attenuating K/BxN arthritis in mast cell-deficient mice Cre-Master mice, suggesting that lineages beyond the MC represent relevant targets in this system. These studies suggest that fullerene derivatives may hold promise both as an assessment tool and as anti-inflammatory therapy of arthritis.

A novel gadolinium-based trimetasphere metallofullerene for application as a magnetic resonance imaging contrast agent.

OBJECTIVE: Macromolecular contrast agents for magnetic resonance imaging (MRI) are useful blood-pool agents because of their long systemic half-life and have found applications in monitoring tumor vasculature and angiogenesis. Macromolecular contrast agents have been able to overcome some of the disadvantages of the conventional small-molecule contrast agent Magnevist (gadolinium-diethylenetriaminepentaacetic acid), such as rapid extravasation and quick renal clearance, which limits the viable MRI time. There is an urgent need for new MRI contrast agents that increase the sensitivity of detection with a higher relaxivity, longer blood half-life, and reduced toxicity from free Gd3+ ions. Here, we report on the characterization of a novel water-soluble, derivatized, gadolinium-enclosed metallofullerene nanoparticle (Hydrochalarone-1) in development as an MRI contrast agent. MATERIALS AND METHODS: The physicochemical properties of Hydrochalarone-1 were characterized by dynamic light scattering (hydrodynamic diameter), atomic force microscopy (particle height), ζ potential analysis (surface charge), and inductively coupled plasma-mass spectrometry (gadolinium concentration). The blood compatibility of Hydrochalarone-1 was also assessed in vitro through analysis of hemolysis, platelet aggregation, and complement activation of human blood. In vitro relaxivities, in vivo pharmacokinetics, and a pilot in vivo acute toxicity study were also performed. RESULTS: An extensive in vitro and in vivo characterization of Hydrochalarone-1 is described here. The hydrodynamic size of Hydrochalarone-1 was 5 to 7 nm depending on the dispersing media, and it was negatively charged at physiological pH. Hydrochalarone-1 showed compatibility with blood cells in vitro, and no significant hemolysis, platelet aggregation, or complement activation was observed in vitro. In addition, Hydrochalarone-1 had significantly higher r1 and r2 in vitro relaxivities in human plasma in comparison with Magnevist and was not toxic at the doses administered in an in vivo pilot acute-dose toxicity study in mice.In vivo MRI pharmacokinetic analysis after a single intravenous injection of Hydrochalarone-1 (0.2 mmol Gd/kg) showed that the volume of distribution at steady state was approximately 100 mL/kg, suggesting prolonged systemic circulation. Hydrochalarone-1 also had a long blood half-life (88 minutes) and increased relaxivity, suggesting application as a promising blood-pool MRI contrast agent. CONCLUSIONS: The evidence suggests that Hydrochalarone-1, with its long systemic half-life, may have significant utility as a blood-pool MRI contrast agent.