Synthesis and evaluation of poly(styrene-co-maleic acid) micellar nanocarriers for the delivery of tanespimycin

Polymeric micelles carrying the heat shock protein 90 inhibitor tanespimycin (17-N-allylamino-17-demethoxygeldanamycin) were synthesized using poly(styrene-co-maleic acid) (SMA) copolymers and evaluated in vitro and in vivo. SMA-tanespimycin micelles were prepared with a loading efficiency of 93%. The micelles incorporated 25.6% tanespimycin by weight, exhibited a mean diameter of 74 ± 7 nm by dynamic light scattering and a zeta potential of -35 ± 3 mV. Tanespimycin was released from the micelles in a controlled manner in vitro, with 62% released in 24h from a pH 7.4 buffer containing bovine serum albumin. The micellar drug delivery systems for tanespimycin showed potent activity against DU145 human prostate cancer cells, with an IC(50) of 230 nM. They further exhibited potent anti-cancer activity in vivo in nu/nu mice bearing subcutaneous DU145 human prostate cancer tumor xenografts, with significantly higher anticancer efficacy as measured by tumor regression when compared to free tanespimycin at an equivalent single dose of 10mg/kg. These data suggest further investigation of SMA-tanespimycin as a promising agent in the treatment of prostate cancer.

Size and surface charge significantly influence the toxicity of silica and dendritic nanoparticles

The influence of size, surface charge and surface functionality of poly(amido amine) dendrimers and silica nanoparticles (SNPs) on their toxicity was studied in immunocompetent mice. After systematic characterization of nanoparticles, they were administered to CD-1 (caesarean derived-1) mice to evaluate acute toxicity. A distinct trend in nanotoxicity based on surface charge and functional group was observed with dendrimers regardless of their size. Amine-terminated dendrimers were fatal at doses >10 mg/kg causing haematological complications such as disseminated intravascular coagulation-like manifestations whereas carboxyl- and hydroxyl-terminated dendrimers of similar sizes were tolerated at 50-fold higher doses. In contrast, larger SNPs were less tolerated than smaller SNPs irrespective of their surface functionality. These findings have important implications in the use of these nanoparticles for various biomedical applications.

Comparison of active and passive targeting of docetaxel for prostate cancer therapy by HPMA copolymer-RGDfK conjugates

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer-docetaxel-RGDfK conjugate was synthesized, characterized, and evaluated in vitro and in vivo in comparison with untargeted low and high molecular weight HPMA copolymer-docetaxel conjugates. The targeted conjugate was designed to have a hydrodynamic diameter below renal threshold to allow elimination post treatment. All conjugates demonstrated the ability to inhibit the growth of DU145 and PC3 human prostate cancer cells and the HUVEC at low nanomolar concentrations. The targeted conjugate showed active binding to α(v)β(3) integrins in both HUVEC and DU145 cells, whereas the untargeted conjugate demonstrated no evidence of specific binding. Efficacy at two concentrations (20 mg/kg and 40 mg/kg) was evaluated in nu/nu mice bearing DU145 tumor xenografts treated with a single dose of conjugates and compared with controls. RGDfK targeted and high molecular weight nontargeted conjugates exhibited the highest antitumor efficacy as evaluated by tumor regression. These results demonstrate that α(v)β(3) integrin targeted polymeric conjugates with improved water solubility, reduced toxicity and ease of elimination post treatment in vivo are promising candidates for prostate cancer therapy.

Anticancer and antiangiogenic activity of HPMA copolymer-aminohexylgeldanamycin-RGDfK conjugates for prostate cancer therapy

Tumor progression is dependent on neoangiogenesis for blood supply. Neovasculature over-express α(v)β(3) integrins which recognize the Arg-Gly-Asp (RGD) sequence in the extracellular matrix. N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers containing side chains terminated in cyclic RGD analogs such as RGDfK show increased accumulation in prostate tumors. Geldanamycin and their derivatives (e.g., aminohexylgeldanamycin (AH-GDM)) are benzoquinone ansamycins that have both antiangiogenic and antitumor activity. In this work the antiangiogenic and antitumor activities of targetable HPMA copolymer-RGDfK-AH-GDM conjugates were compared with non-targetable systems in vitro and in vivo. Copolymer-drug conjugates containing RGDfK in the side chains showed superior activity against endothelial and prostate cancer cell lines in vitro, as well as higher inhibition of angiogenesis in vivo. At equimolar doses of the drug, the RGDfK containing conjugates showed significantly higher antitumor activity in nude mice bearing DU-145 human prostate cancer xenografts. These findings suggest the utility of HPMA copolymer-RGDfK conjugates for targeted delivery of geldanamycin analogs with a dual mode of action.

TISSUE MAST CELLS AND ACUTE INFLAMMATION IN EXPERIMENTAL CUTANEOUS MUCORMYCOSIS OF NORMAL, 48/80-TREATED, AND DIABETIC RATS

The role of the tissue mast cells in relation to the acute inflammatory reaction to experimental cutaneous mucormycosis was studied histologically in normal rats, in animals whose tissue mast cells had been depleted of their cytoplasmic granules prior to infection by the administration of compound 48/80 and in others in whom acute alloxan diabetes with acidosis had been produced before injection of the fungus. The discharge of the tissue mast cell granules in normal rats occurred within minutes at the site of infection and appeared to initiate the rapid onset of acute inflammation. The degranulation of the tissue mast cells subsided in a short time and the cells reassumed a normal histologic appearance while inflammation progressed with the formation of circumscribed lesions. In animals pretreated with compound 48/80 in which the tissue mast cells contained no granules, the onset of inflammation was briefly delayed, the intensity of the process was somewhat decreased, fibroblastic proliferation was retarded, and the fungus growth in the early lesions was increased. However, the infection did not spread and the lesions were well localized. The tissue mast cells in the diabetic and acidotic rats completely failed to discharge their cytoplasmic granules, the onset and intensity of the acute inflammatory response were markedly delayed and decreased and the infection progressed rapidly with massive fungus growth invading adjacent tissues. A relationship between the discharged tissue mast cell granules and eosinophilic granulocytes was noted since the latter were numerous among the inflammatory cell exudate in normal rats and scarce in the lesions of the diabetic animals. It is concluded that a function of the tissue mast cells in the normal rat is the rapid initiation of acute inflammation at the site of injury and that degranulation of these cells prior to infection somewhat delays the inflammatory response and therefore slightly diminishes host resistance. Furthermore, a severe metabolic disorder such as acute alloxan diabetes with acidosis, inhibits the normal function of the tissue mast cells, delays and decreases inflammation, and in this manner contributes to the greatly increased susceptibility of the host to infection.

Endocytic uptake of a large array of HPMA copolymers: Elucidation into the dependence on the physicochemical characteristics

Endocytic uptake and subcellular trafficking of a large array of HPMA (N-(2-hydroxypropyl)methacrylamide) based copolymers possessing positively or negatively charged residues, or hydrophobic groups were evaluated by flow cytometry and living cell confocal microscopy in cultured prostate cancer cells. The degrees of cellular uptake of various copolymer fractions with narrow polydispersities were quantified. The copolymer charge was the predominant physicochemical feature in terms of cellular uptake. Fast and efficient uptake occurred in positively charged copolymers due to non-specific adsorptive endocytosis, whereas slow uptake of negatively charged copolymers was observed. The uptake of copolymers was also molecular weight dependent. The copolymers were internalized into the cells through multiple endocytic pathways: positively charged copolymers robustly engaged clathrin-mediated endocytosis, macropinocytosis and dynamin-dependent endocytosis, while weakly negatively charged copolymers weakly employed these pathways; strongly negatively charged copolymers only mobilized macropinocytosis. HPMA copolymer possessing 4 mol% of moderately hydrophobic functional groups did not show preferential uptake. All copolymers ultimately localized in late endosomes/lysosomes via early endosomes; with varying kinetics among the copolymers. This study indicates that cell entry and subsequent intracellular trafficking of polymeric drug carriers are strongly dependent on the physicochemical characteristics of the nanocarrier, such as charge and molecular weight.

Biorecognition and subcellular trafficking of HPMA copolymer-anti-PSMA antibody conjugates by prostate cancer cells

A new generation of antibodies against the prostate specific membrane antigen (PSMA) has been proven to bind specifically to PSMA molecules on the surface of living prostate cancer cells. To explore the potential of anti-PSMA antibodies as targeting moieties for macromolecular therapeutics for prostate cancer, fluorescently labeled HPMA (N-(2-hydroxypropyl)methacrylamide) copolymer-anti-PSMA antibody conjugates (P-anti-PSMA) were synthesized and the mechanisms of their endocytosis and subcellular trafficking in C4-2 prostate cancer cells were studied. Radioimmunoassays showed the dissociation constants of P-anti-PSMA for C4-2 prostate cancer cells in the low nanomolar range, close to values for free anti-PSMA. It indicated that conjugation of anti-PSMA to HPMA copolymers did not compromise their binding affinity. The rate of endocytosis of P-anti-PSMA was much faster than that of control HPMA copolymer conjugates containing nonspecific IgG. Selective pathway inhibitors of clathrin-mediated endocytosis and of macropinocytosis inhibited the internalization of P-anti-PSMA. Inhibition of clathrin-mediated endocytosis was further evidenced by down-regulation of clathrin heavy chain expression by siRNA. Using a dominant-negative mutant of dynamin (Dyn K44A) to abolish the clathrin-, caveolae-independent endocytic pathway, we found that some of P-anti-PSMA adopted this pathway to be endocytosed into C4-2 cells. Thus multiple receptor-mediated endocytic pathways, including clathrin-mediated endocytosis, macropinocytosis, and clathrin-, caveolae-independent endocytosis, were involved in the internalization of P-anti-PSMA. The extent of the participation of each pathway in P-anti-PSMA endocytosis was estimated. Membrane vesicles containing P-anti-PSMA rapidly colocalized with membrane vesicles overexpressing Rab7, a late endosome localized protein, demonstrating that a part of P-anti-PSMA was transported to late endosomes.

[Rheumatic diseases in pregnancy]

Rheumatic diseases can influence the reproduction, the course of pregnancy and the development of the fetus. The inflammatory rheumatic disease itself can be modulated in its activity in terms of amelioration or exacerbation of the rheumatic symptoms. The associations between rheumatic diseases and pregnancy will be illustrated with rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and systemic lupus erythematosus as examples. Antirheumatic drug therapy during pregnancy and the breast feeding period has to be adapted critically.