Targeting CD44 receptor-positive lung tumors using polysaccharide-based nanocarriers: Influence of nanoparticle size and administration route.

New approaches that are more efficient and able to specifically reach lung tumors are needed. We developed new hyaluronan-based nanoparticles targeting CD44 receptors of two different sizes and compared their lung cancer cells targeting efficacy in vitro and in vivo. The nanoparticles' cellular uptake was dose-dependent, and specific to hyaluronan receptors, particularly CD44. The binding and internalization differed according to nanoparticle size. In vivo biodistribution studies in two orthotopic lung tumor models showed that intrapulmonary nebulized nanoparticles accumulated in lungs, but not in the tumor nodules. In contrast, despite a significant liver capture, intravenous injection led to a better accumulation of the nanoparticles in the lung tumors compared with the surrounding healthy lung tissues. We demonstrated that the hyaluronan-based nanoparticles size plays significant role in cellular uptake and biodistribution. Small nanoparticles showed active targeting of CD44-overexpressing tumors, suggesting that they could be used as drug-delivery system. FROM THE CLINICAL EDITOR: Combating cancers remains an important goal in clinical medicine. In this study, the authors investigated the ability of two hyaluronan-based nanoparticles targeting CD44 receptors to home in on lung cancer cells in an in-vivo orthotropic model. The preferential uptake of smaller sized nanoparticles via intravenous route has further enhanced the existing knowledge of future drug designs.

Anti-tumor efficacy of hyaluronan-based nanoparticles for the co-delivery of drugs in lung cancer.

Combinations of therapeutic agents could synergistically enhance the response of lung cancer cells. Co-delivery systems capable of transporting chemotherapeutics with different physicochemical properties and with the simultaneous release of drugs remain elusive. Here, we assess the ability of nanoparticles of 30-nm diameter obtained from the self-assembly of hyaluronan-based copolymer targeting CD44 receptors to encapsulate both gefitinib and vorinostat for effective combinational lung cancer treatment. Drug loading was performed by nanoprecipitation. Drug release experiments showed a slow release of both drugs after 5 days. Using two- and three-dimensional lung adenocarcinoma cell cultures, we observed that the nanoparticles were mostly found at the periphery of the CD44-expressing spheroids. These drug-loaded nanoparticles were as cytotoxic as free drugs in the two- and three-dimensional systems and toxicity was due to apoptosis induction. In mouse models, intravenous injection of hyaluronan-based nanoparticles showed a selective delivery to subcutaneous CD44-overexpressing tumors, despite a significant liver capture. In addition, the systemic toxicity of the free drugs was reduced by their co-delivery using the nanoparticles. Finally, intrapulmonary administration of drug-loaded nanoparticles, to avoid a possible hepatic toxicity due to their accumulation in the liver, showed a stronger inhibition of orthotopic lung tumor growth compared to free drugs. In conclusion, hyaluronan-based nanoparticles provide active targeting partially mediated by CD44, less-toxic drug release and improved antitumor efficiency.

Amphiphilic PEO-b-PBLG diblock and PBLG-b-PEO-b-PBLG triblock copolymer based nanoparticles: doxorubicin loading and in vitro evaluation.

Huisgen's 1,3-dipolar cycloaddition ("Click Chemestry") has been used to prepare amphiphilic PEO-b-PBLG diblock and PBLG-b-PEO-b-PBLG triblock copolymers as potential carriers of anticancer drugs. Spherical and flower shaped micelles (D ≈ 100 nm) were obtained from diblock and triblock copolymers respectively. DOX was effectively encapsulated up to 18 wt.% and 50-60% of it was steadily released from the micelles over a period of 7 d. Flow cytometry and fluorescence microscopy confirmed the effective intracellular uptake as well as the sustained release of DOX from micelles. These results suggest that the diblock as well as triblock copolymers are promising carriers for intra-cellular drug delivery.

Oral delivery of anticancer drugs III: formulation using drug delivery systems.

In the past few years, the growth of nanometric size drug delivery systems (DDS) has burst into challenging innovations enabling real progresses to achieve oral delivery of anticancer drugs. DDS, such as polymeric nanoparticles, micelles, dendrimers and lipid-based formulations enable physico-chemical properties of cytotoxic agents to be improved and oral bioavailability to be enhanced. In this review we highlight current DDS used for the oral delivery of anticancer drugs.

Oral delivery of anticancer drugs I: general considerations.

Historically, most of anticancer drugs were delivered by the intravenous route which is the most direct one leading to immediate and complete bioavailability of the drugs. However, this administration route could result in several side effects and requires a clinic or hospitalization visit, nursing and palliative treatment. For these latter reasons, oral delivery of anticancer drugs is nowadays more and more considered, including already marketed drugs. In this first review, we aim to identify general considerations for the oral delivery of anticancer drugs. In the second and the third reviews we respectively discuss the prodrug strategy and the use of drug delivery systems to improve the oral bioavailability of anticancer drugs.

Oral delivery of anticancer drugs II: the prodrug strategy.

Many anticancer drugs are sparingly water soluble and they show a low permeability at the intestinal level. Furthermore, their oral bioavailability is impaired because they are substrates of the cytochrome P450 and of the efflux pumps. The prodrug strategy, which is discussed in the present review, represents one of the different approaches to overcome these obstacles. In this review, we highlight the progresses of clinical development in the prodrug area for the oral administration of anticancer drugs.

Synthesis and self-assembly of branched glycopolypeptides: effect of topology and conformation.

Block copolymers combining peptide and saccharide moieties may play a significant role in future applications of polymers in biology, as they can be viewed as simplified synthetic analogues of glycosylated proteins, which display a wide range of biological functions in nature. While a small number of oligosaccharides containing synthetic polypeptides have been described so far, here we present the efficient preparation of a small library of tree-like glycopolypeptides incorporating poly(gamma-benzyl-L-glutamate) having different molecular weights. A comprehensive study of the self-assembly of these unique grafted macromolecular structures is detailed. All the copolymers presented the ability to spontaneously self-assemble into spherical micelles in water; a property assigned both to the spontaneous curvature of the grafted oligosaccharide segments and to the favorable hydrophilic to hydrophobic volume ratios. These hydrophilic to hydrophobic volume ratios were efficiently counterbalanced by the self-assembly of blends incorporating poly(gamma-benzyl-L-glutamate) homopolymers - this simple approach minimized the influence of the spontaneous curvature of the oligosaccharides' dendrons and afforded a transition to lamellar structures in solution.

How to conduct and interpret ITC experiments accurately for cyclodextrin-guest interactions.

Isothermal titration calorimetry (ITC) is one of the most interesting methods for the characterization of the interaction mechanisms of cyclodextrins (CDs) with drugs. In this review we explain how to conduct ITC experiments correctly for CD-guest interactions, how to choose an accurate fitting model for the titration curve and how to interpret carefully the ITC results. Finally, the use of ITC for the characterization of CD-containing nanoparticles is discussed.

Intestinal permeation enhancement of docetaxel encapsulated into methyl-ß-cyclodextrin/poly(isobutylcyanoacrylate) nanoparticles coated with thiolated chitosan.

In this study we investigated the potential of mucoadhesive nanoparticles to enhance the intestinal permeability of docetaxel (Dtx). These nanoparticles were composed of methyl-ß-cyclodextrin (Me-ß-CD) combined with poly(isobutylcyanoacrylate) and coated with thiolated chitosan. In order to encapsulate the highest amount of Dtx into nanoparticles, the anionic emulsion polymerization of isobutylcyanoacrylate was carried out in a solution of Me-ß-CD/Dtx inclusion complex. The resulting nanoparticles were spherical with diameters ranging from 200 to 400 nm, and positively charged. Depending on the formulation, the encapsulation efficiency of Dtx was 70-80%. In vitro experiments in simulated intestinal medium containing 1% w/v of pancreatin showed that Dtx was gradually released to reach 60% after 24h and 100% after 48 h. The capacity of these nanoparticles to enhance the flux of Dtx across the intestinal membrane was then investigated using the Ussing chamber technique. The intestinal permeation of Dtx loaded into nanoparticles was found to be higher than the ethanol control solution of Dtx. Interestingly, when mucoadhesive interactions between nanoparticles and the mucosa were avoided, the intestinal permeation of Dtx significantly decreased, confirming that the mucoadhesion of the nanoparticles was a mandatory condition to enhance the intestinal permeation of Dtx.

Bivalent sequential binding of docetaxel to methyl-ß-cyclodextrin.

New docetaxel (Dtx) and cyclodextrin (CD) inclusion complexes having improved apparent water solubility (up to 9.98mgmL(-1)) were obtained from phase solubility diagrams. γ-CD and SBE-ß-CD offered only poor solubility enhancements while considerable increases in apparent solubility were obtained with Me-ß-CD (20%, w/w) and HP-ß-CD (40%, w/w) (9.98mgmL(-1) and 7.43mgmL(-1), respectively). The complexation mechanism between Dtx and Me-ß-CD was investigated by circular dichroism spectrometry, two-dimensional (1)H NMR (NOESY) in D(2)O, isothermal titration calorimetry (ITC) and molecular docking calculations. Circular dichroism and NOESY confirmed the existence of non-covalent interactions between Dtx and Me-ß-CD and suggested that the tert-butyl group (C(6)-C(9)) and two aromatic groups (C(24)-C(29) and C(30)-C(35)) of Dtx interacted with the Me-ß-CD molecules. The combination of ITC results to molecular docking calculations led to the identification of an unconventional sequential binding mechanism between Me-ß-CD and Dtx. In this sequential binding, a Me-ß-CD molecule first interacted with both tert-butyl and C(30)-C(35) aromatic groups (K(1): 744M(-1)). Then a second Me-ß-CD molecule interacted with the C(24)-C(29) aromatic group (K(2): 202M(-1)). The entropy of the first interaction was positive, whereas a negative value of entropy was found for the second interaction. The opposite behavior observed for these two sites was explained by differences in the hydrophobic contact surface and functional group flexibility.