Multifunctional polyurethane-urea nanoparticles to target and arrest inflamed vascular environment: a potential tool for cancer therapy and diagnosis.

Activation of inflammatory pathways in endothelial cells contributes to tumour growth and progression in multiple human cancers. Cellular adhesion molecules are involved in leukocyte recruitment to the vascular inflammatory environment where it plays a critical role in angiogenesis, suppression of apoptosis, proliferation, invasion and metastasis. We describe here the development of streptavidin-coated polyurethane-urea nanoparticles as multifunctional nanocarriers for fluorescence imaging or targeting of the tumour environment to identify and arrest the vascular network irrigating the tumour tissue. The design of these multifunctional nanoparticles involves incorporating streptavidin to the nanoparticle polymeric matrix. The obtained nanoparticles are spherical and exhibit an average diameter of 70-74 nm. Streptavidin-coated nanoparticles spontaneously bind biotinylated antibodies against VCAM-1 and ICAM-1 which in vitro and in vivo specifically attached to inflamed endothelial cells. Indeed the incorporation of CBO-P11 (a specific inhibitor of the vascular endothelial growth factor proangiogenic and proinflammatory pathway) to these nanoparticles allows a targeted pharmacological effect thereby decreasing the proliferation only in inflamed endothelial cells. The multiple functionalisation strategy described here could be exploited for tumour diagnostics or targeted drug delivery to tumour vasculature with a good safety profile and an attractive array of possibilities for biomedical applications.

Adenoviral dominant-negative soluble PDGFRß improves hepatic collagen, systemic hemodynamics, and portal pressure in fibrotic rats.

BACKGROUND & AIMS: Platelet-derived growth factor (PDGF) is the most potent stimulus for proliferation and migration of stellate cells. PDGF receptor ß (PDGFRß) expression is an important phenotypic change in myofibroblastic cells that mediates proliferation and chemotaxis. Here we analyzed the relationship between PDGFRß expression, hemodynamic deterioration, and fibrosis in CCl(4)-treated rats. Thereafter, we investigated the effects produced by an adenovirus encoding a dominant-negative soluble PDGFRß (sPDGFRß) on hemodynamic parameters, PDGFRß signaling pathway, and fibrosis. METHODS: Mean arterial pressure, portal pressure, PDGFRß mRNA expression, and hepatic collagen were assessed in 6 controls and 21 rats induced to hepatic fibrosis/cirrhosis. Next, 30 fibrotic rats were randomized into three groups receiving iv saline and an adenovirus encoding for sPDGFRß or ß-galactosidase. After 7days, mean arterial pressure, portal pressure, serum sPDGFRß, and hepatic collagen were measured. RESULTS: CCl(4)-treated animals for 18weeks showed a significantly higher increase in PDGFRß mRNA compared to those treated for 13weeks and control rats. In CCl(4)-treated rats, the fibrous tissue area ranged from moderate to severe fibrosis. A direct relationship between the degree of fibrosis, hemodynamic changes, and PDGFRß expression was observed. Fibrotic rats transduced with the adenovirus encoding sPDGFRß showed increased mean arterial pressure, decreased portal pressure, lower activation of the PDGFRß signaling pathway, and reduced hepatic collagen than fibrotic rats receiving ß-galactosidase or saline. CONCLUSIONS: PDGFRß activation closely correlates with hemodynamic disorders and increased fibrosis in CCl(4)-treated rats. Adenoviral dominant negative soluble PDGFRß improved fibrosis. As a result, the hemodynamic abnormalities were ameliorated.

Inactivation of extrahepatic vascular Akt improves systemic hemodynamics and sodium excretion in cirrhotic rats.

BACKGROUND & AIMS: Increased activity of the vascular Akt/eNOS signaling pathway is involved in the hemodynamic and renal complications developed by patients and rats with cirrhosis and ascites. This occurs in the setting of impaired Akt/eNOS activity within the cirrhotic liver. Here we assessed the feasibility of selectively inhibiting vascular eNOS without further impairing the intrahepatic activity of this enzyme. Ultimately, we sought to determine whether endothelial transduction of a constitutively inactive mutant of Akt (AA-Akt) improves circulatory function and sodium excretion in cirrhotic rats with ascites. METHODS: First, we administered recombinant adenoviruses that encode the ß-galactosidase gene (ß-gal) to 5 control rats and 5 cirrhotic rats with ascites and analyzed their tissue distribution by chemiluminescence. Next, urine samples were obtained from 18 cirrhotic rats with ascites and then the animal randomly received saline or adenoviruses containing the ß-gal or the AA-Akt genes. Following a 24-h urine collection period, hemodynamic studies were performed and tissue samples were obtained to analyze Akt and eNOS expressions. RESULTS: No ß-gal activity was detected in the liver of cirrhotic rats compared to that of controls. This was paralleled by increased ß-gal activity in other territories such as the thoracic aorta. AA-Akt transduction improved systemic hemodynamics, splanchnic perfusion pressure and renal excretory function in comparison with cirrhotic rats transduced with ß-gal adenoviruses or receiving saline. Moreover, the AA-Akt transgene did not modify portal pressure. CONCLUSIONS: Inactivation of extrahepatic vascular Akt and the concomitant decrease in nitric oxide expression ameliorate systemic hemodynamics and renal excretory function in experimental cirrhosis.

Vascular endothelial growth factor and angiopoietin-2 play a major role in the pathogenesis of vascular leakage in cirrhotic rats.

BACKGROUND AND AIMS: The extent and molecular mechanisms governing plasma extravasation and formation of ascites in cirrhosis are unknown. Vascular endothelial growth factor-A (VEGF-A) and angiopoietin-2 (Ang-2) are endogenous substances with powerful vascular permeability effects. We assessed regional blood flow, vascular leakage, mRNA and tissular expression of VEGF-A and Ang-2 and vascular permeability following VEGF receptor 2 blockade in control and cirrhotic rats to define the vascular territories showing altered vascular permeability in cirrhosis and to determine whether VEGF-A and Ang-2 are involved in this phenomenon. METHODS: Arterial blood flow was analysed with the coloured microsphere method. Vascular leakage was measured and visualised with the dye Evan's Blue and colloidal carbon techniques, respectively. VEGF-A and Ang-2 expression were determined by real-time polymerase chain reaction (RT-PCR), immunohistochemistry and western blot. The effect on vascular permeability induced by VEGFR(2) blockade was assessed by administration of the receptor inhibitor SU11248. RESULTS: Arterial blood flow was increased in the mesentery, pancreas and small intestine but not in the kidney and spleen of cirrhotic rats as compared to controls. Increased vascular leakage was observed in the mesentery and liver, where colloidal carbon spread from microvessels to the adjacent fibrotic tracts. Increased hepatic and mesenteric expression of VEGF-A and Ang-2 was found in cirrhotic rats as compared to controls. Blockade of VEGFR(2) markedly reduced hepatic and mesenteric vascular leakage in cirrhotic rats. CONCLUSIONS: Enhanced endothelial permeability is restricted to the hepatic and mesenteric vascular beds in cirrhotic rats with ascites and VEGF-A and Ang-2 are key factors in the signalling pathways regulating this dysfunction.