Claudia Conte

Improving the efficacy of inhaled drugs in cystic fibrosis: Challenges and emerging drug delivery strategies

Cystic fibrosis (CF) is the most common autosomal recessive disease in Caucasians associated with early death. Although the faulty gene is expressed in epithelia throughout the body, lung disease is still responsible for most of the morbidity and mortality of CF patients. As a local delivery route, pulmonary administration represents an ideal way to treat respiratory infections, excessive inflammation and other manifestations typical of CF lung disease. Nonetheless, important determinants of the clinical outcomes of inhaled drugs are the concentration/permanence at the lungs as well as the ability of the drug to overcome local extracellular and cellular barriers. This review focuses on emerging delivery strategies used for local treatment of CF pulmonary disease. After a brief description of the disease and formulation rules dictated by CF lung barriers, it describes current and future trends in inhaled drugs for CF. The most promising advanced formulations are discussed, highlighting the advantages along with the major challenges for researchers working in this field.

Nanocapsules Based on Linear and Y-Shaped 3-Miktoarm Star-Block PEO-PCL Copolymers as Sustained Delivery System for Hydrophilic Molecules

Well-defined amphiphilic Y-shaped miktoarm star-block copolymers of PEO and PCL were synthesized by ring-opening polymerization of ε-caprolactone initiated by a PEO-bound lysine macroinitiator. The copolymers were characterized by (1)H NMR, SEC, DSC, and WAXD techniques. Separate PCL and PEO crystalline phases occur in melt-crystallized copolymers when their segmental lengths were comparable and the PCL content was ≤80 wt %. Self-assembling of these copolymers in aqueous medium led to nanoaggregates with low critical aggregation concentration values (0.35 to 1.6 mg·L(-1)) and size depending on composition. Despite the fact that copolymers were not prone to self-organize in vesicles, once processed by a novel w/o emulsion-melting-sonication technique, they gave nanocapsules with a water core and a hydrophilic surface. A macromolecular fluorescent dye was effectively loaded and released at sustained rate by optimizing nanocapsule formulation. The results demonstrate that amphiphilic block copolymers can be assembled in different kinds of nanomorphologies independently of their hydrophilic/hydrophobic balance and architecture through specifically designed preparation techniques.

Core-shell biodegradable nanoassemblies for the passive targeting of docetaxel: features, antiproliferative activity and in vivo toxicity.

UNLABELLED Amphiphilic block copolymers of poly(ɛ-caprolactone) and poly(ethylene oxide) were assembled in core-shell nanoparticles (NPs) by a melting-sonication technique (MeSo). The entrapment of the poorly water-soluble anticancer drug docetaxel (DTX), nanocarrier cytotoxicity toward different cells and toxicity in mice were investigated. The encapsulation mechanism was rationalized and related to copolymer properties such as crystallinity and drug solubility in the copolymer phase. DTX release from NPs occurred in 2 drug pulses over 30 days. DTX entrapment in NPs strongly decreased haemolysis of erythrocytes in comparison with a commercial DTX formulation. In comparison with free DTX, NPs were both more efficient in inhibiting cell growth of breast and prostate cancer cells and less toxic in experimental animal models. The results of this study indicate that MeSo is an interesting technique for the achievement of peculiar core-shell nanocarriers for the passive targeting and sustained release of poorly water-soluble anticancer drugs. FROM THE CLINICAL EDITOR In this study, stealth nanoparticles of PEO/PCL block copolymers for passive targeting of docetaxel to solid tumors were developed using a novel technique. The studied properties of NPs suggest strong potential as anticancer drug-delivery system.

Biodegradable nanoparticles sequentially decorated with Polyethyleneimine and Hyaluronan for the targeted delivery of docetaxel to airway cancer cells

BackgroundNovel polymeric nanoparticles (NPs) specifically designed for delivering chemotherapeutics in the body and aimed at improving treatment activity and selectivity, cover a very relevant area in the field of nanomedicine.Here, we describe how to build a polymer shell of Hyaluronan (HA) and Polyethyleneimine (PEI) on biodegradable NPs of poly(lactic-co-glycolic) acid (PLGA) through electrostatic interactions and to achieve NPs with unique features of sustained delivery of a docetaxel (DTX) drug cargo as well as improved intracellular uptake.ResultsA stable PEI or HA/PEI shell could be obtained by careful selection of layering conditions. NPs with exquisite stability in salt and protein-rich media, with size and surface charge matching biological requirements for intravenous injection and endowed with sustained DTX release could be obtained. Cytotoxicity, uptake and activity of both PLGA/PEI/HA and PLGA/PEI NPs were evaluated in CD44(+) (A549) and CD44(−) (Calu-3) lung cancer cells. In fact, PEI-coated NPs can be formed after degradation/dissociation of the surface HA because of the excess hyaluronidases overexpressed in tumour interstitium. There was no statistically significant cytotoxic effect of PLGA/PEI/HA and PLGA/PEI NPs in both cell lines, thus suggesting that introduction of PEI in NP shell was not hampered by its intrinsic toxicity. Intracellular trafficking of NPs fluorescently labeled with Rhodamine (RHO) (RHO-PLGA/PEI/HA and RHO-PLGA/PEI NPs) demonstrated an increased time-dependent uptake only for RHO-PLGA/PEI/HA NPs in A549 cells as compared to Calu-3 cells. As expected, RHO-PLGA/PEI NP uptake in A549 cells was comparable to that observed in Calu-3 cells. RHO-PLGA/PEI/HA NPs internalized into A549 cells showed a preferential perinuclear localization. Cytotoxicity data in A549 cells suggested that DTX delivered through PLGA/PEI/HA NPs exerted a more potent antiproliferative activity than free DTX. Furthermore, DTX-PLGA/PEI NPs, as hypothetical result of hyaluronidase-mediated degradation in tumor interstitium, were still able to improve the cytotoxic activity of free DTX.ConclusionsTaken together, results lead us to hypothesize that biodegradable NPs coated with a PEI/HA shell represent a very promising system to treat CD44 overexpressing lung cancer. In principle, this novel nanocarrier can be extended to different single drugs and drug combinations taking advantage of the shell and core properties.

Nanoassembly of an amphiphilic cyclodextrin and Zn(II)-phthalocyanine with the potential for photodynamic therapy of cancer

Due to their poor solubility and propensity to aggregate in aqueous media, therapeutic application of several photosensiting agents, such as phthalocyanines, in photodynamic therapy (PDT) of solid tumors is severely hampered. With the aim to propose a novel nanotechnological approach, in this paper biodegradable nanoassemblies based on heptakis (2-oligo(ethyleneoxide)-6-hexadecylthio-)-β-CD (SC16OH) and zinc-phthalocyanine (ZnPc) were developed and tested. Nanoassemblies, prepared by the emulsion–solvent evaporation technique, displayed a hydrodynamic diameter around 200 nm, a negative zeta potential and a satisfactory entrapment efficiency of ZnPc. Steady-state and time resolved fluorescence emission spectroscopy studies showed the entrapment of ZnPc as a monomer in the carrier, with a low tendency to self-aggregate and consequently a fairly good propensity to generate singlet oxygen after photoactivation. The interaction of ZnPc with SC16OH was elucidated by 1H-NMR, which suggested the formation of complexes between drug and both hydrophobic and hydrophilic moieties of the amphiphile. Finally, in vitro potential of the nanoassembly was evaluated in HeLa cells by following cellular uptake and photobiological activity. Overall, results suggest the suitability of the nanoassembly based on SC16OH for delivering ZnPc to cancer cells, thus inducing photodynamic anticancer effects.

Polymeric Nanoparticles for Cancer Photodynamic Therapy.

In chemotherapy a fine balance between therapeutic and toxic effects needs to be found for each patient, adapting standard combination protocols each time. Nanotherapeutics has been introduced into clinical practice for treating tumors with the aim of improving the therapeutic outcome of conventional therapies and of alleviating their toxicity and overcoming multidrug resistance. Photodynamic therapy (PDT) is a clinically approved, minimally invasive procedure emerging in cancer treatment. It involves the administration of a photosensitizer (PS) which, under light irradiation and in the presence of molecular oxygen, produces cytotoxic species. Unfortunately, most PSs lack specificity for tumor cells and are poorly soluble in aqueous media, where they can form aggregates with low photoactivity. Nanotechnological approaches in PDT (nanoPDT) can offer a valid option to deliver PSs in the body and to solve at least some of these issues. Currently, polymeric nanoparticles (NPs) are emerging as nanoPDT system because their features (size, surface properties, and release rate) can be readily manipulated by selecting appropriate materials in a vast range of possible candidates commercially available and by synthesizing novel tailor-made materials. Delivery of PSs through NPs offers a great opportunity to overcome PDT drawbacks based on the concept that a nanocarrier can drive therapeutic concentrations of PS to the tumor cells without generating any harmful effect in non-target tissues. Furthermore, carriers for nanoPDT can surmount solubility issues and the tendency of PS to aggregate, which can severely affect photophysical, chemical, and biological properties. Finally, multimodal NPs carrying different drugs/bioactive species with complementary mechanisms of cancer cell killing and incorporating an imaging agent can be developed. In the following, we describe the principles of PDT use in cancer and the pillars of rational design of nanoPDT carriers dictated by tumor and PS features. Then we illustrate the main nanoPDT systems demonstrating potential in preclinical models together with emerging concepts for their advanced design.

Pulmonary drug delivery: a role for polymeric nanoparticles?

Pulmonary drug delivery represents the best way of treating lung diseases, since it allows direct delivery of the drug to the site of action, with few systemic effects. Meanwhile, the lungs may be used as a portal of entry to the body, allowing systemic delivery of drugs via the airway surfaces into the bloodstream. In both cases, the therapeutic effect of the inhaled drug can be optimized by embedding it in appropriately engineered inhalable carriers, which can protect the drug against lung defense mechanisms and promote drug transport across the extracellular and cellular barriers. To this purpose, the attention has been very recently focused on polymeric nanoparticles (NPs). The aim of this review is to offer an overview on the recent advances in NPs for pulmonary drug delivery. After a description of the main challenges encountered in developing novel inhaled products, the design rules to engineer polymeric NPs for inhalation, and in so doing to overcome barriers imposed by the lungs anatomy and physiology, are described. Then, the state-of-art on inhalable biocompatible polymeric NPs based on enzymatically-degradable natural polymers and biodegradable poly(ester)s is presented, with a special focus on NP-based dry powders for inhalation. Finally, the in vitro/in vivo models useful to address the never-ending toxicological debate related to the use of NPs for inhalation are described.

Skin transport of PEGylated poly(ε-caprolactone) nanoparticles assisted by (2-hydroxypropyl)-β-cyclodextrin

The aim of this work was to investigate the potential of small nanoparticles (NPs) made of a poly(ethylene glycol)-poly(ε-caprolactone)-amphiphilic diblock copolymer (PEG-b-PCL, PEG=2kDa and PCL=4.2kDa) as drug carrier system through the skin. Zinc(II) phthalocyanine (ZnPc), selected as lipophilic and fluorescent model molecule, was loaded inside NPs by a melting/sonication procedure. Loaded NPs with a hydrodynamic diameter around 60nm, a slightly negative zeta potential and a ZnPc entrapment dependent on polymer/ZnPc ratio were obtained. Spectroscopic investigations evidenced that ZnPc was entrapped in monomeric form maintaining its emission properties. The transport of ZnPc through porcine ear skin was evaluated on Franz-type diffusion cells after treatment with different vehicles (water or PEG 0.4kDa) containing free ZnPc or ZnPc-loaded NPs without and with (2-hydroxypropyl)-β-cyclodextrin (HPβCD) as permeation enhancer. Independently of the sample tested, ZnPc was transported in the skin without reaching receptor compartment. On the other hand, ZnPc was found in the skin in large amount and also in the viable epidermis when delivered through NPs associated with HPβCD, especially in conditions limiting water evaporation. Fluorescence images of skin samples after 24h of permeation were in line with ZnPc dosage in the skin and demonstrated the ability of NPs covalently tagged with rhodamine to penetrate the skin and to locate in the intercellular spaces. Insight into skin chemical properties upon application of NPs by confocal Raman spectroscopy demonstrated that HPβCD caused an alteration of water profile in the skin, highly reducing the degree of hydration at stratum corneum/viable epidermis interface which can promote NP transport. Taken together, these results highlight PEG-b-PCL NPs coupled with HPβCD as a novel vehicle for the skin delivery of highly lipophilic compounds paving the way to several applications.

Antitumor activity of PEGylated biodegradable nanoparticles for sustained release of docetaxel in triple-negative breast cancer.

With the aim to find novel therapeutical approaches for triple-negative breast cancer (TNBC) treatment, we have developed a powder for i.v. injection based on cyclodextrins and docetaxel (DTX)-loaded polyethyleneglycol-poly(epsilon-caprolactone) nanoparticles (DTX-NPs). Nanoparticles are designed to concentrate at tumor level by enhanced permeability and retention effect and release drug cargo at a sustained rate in the blood and in tumor interstitium. DTX-NPs of around 70 nm, shielding proteins and allowing a sustained DTX release for about 30 days, were produced by melting sonication technique. DTX-NPs were associated to hydroxypropyl-β-cyclodextrin to give a powder for injection with excellent dispersibility and suitable for i.v. administration. DTX-NPs were as efficient as free DTX in inhibiting cell growth of MDA-MB231 cells, even at low concentrations, and displayed a comparable in vivo antitumor efficacy and better survival in a TNBC animal model as compared with DTX commercial formulation (Taxotere(®)). In conclusion, PEGylated biodegradable DTX-NPs highlighted their potential in the treatment of aggressive TNBC providing a foundation for future clinical studies.

VLPs and particle strategies for cancer vaccines

Effective delivery of tumor antigens to APCs is one of the key steps for eliciting a strong and durable immune response to tumors. Several cancer vaccines have been evaluated in clinical trials, based on soluble peptides, but results have not been fully satisfactory. To improve immunogenicity particles provide a valid strategy to display and/or incorporate epitopes which can be efficiently targeted to APCs for effective induction of adaptive immunity. In the present review, we report some leading technologies for developing particulate vaccines employed in cancer immunotherapy, highlighting the key parameters for a rational design to elicit both humoral and cellular responses.