Controlled drug delivery in tissue engineering

The concept of tissue and cell guidance is rapidly evolving as more information regarding the effect of the microenvironment on cellular function and tissue morphogenesis become available. These disclosures have lead to a tremendous advancement in the design of a new generation of multifunctional biomaterials able to mimic the molecular regulatory characteristics and the three-dimensional architecture of the native extracellular matrix. Micro- and nano-structured scaffolds able to sequester and deliver in a highly specific manner biomolecular moieties have already been proved to be effective in bone repairing, in guiding functional angiogenesis and in controlling stem cell differentiation. Although these platforms represent a first attempt to mimic the complex temporal and spatial microenvironment presented in vivo, an increased symbiosis of material engineering, drug delivery technology and cell and molecular biology may ultimately lead to biomaterials that encode the necessary signals to guide and control developmental process in tissue- and organ-specific differentiation and morphogenesis.

Engineered PLGA nano- and micro-carriers for pulmonary delivery: challenges and promises

Objectives

The aim of this review is to summarize the current state-of-the-art in poly(lactic-co-glycolic acid) (PLGA) carriers for inhalation. It presents the rational of use, the potential and the recent advances in developing PLGA microparticles and nanoparticles for pulmonary delivery. The most promising particle engineering strategies are discussed, highlighting the advantages along with the major challenges for researchers working in this field.

Key findings

Biodegradable polymer carriers, such as PLGA particles, may permit effective protection and long-term delivery of the inhaled drug and, when adequately engineered, its efficient transport to the target. The carrier can be designed for inhalation on the basis of several strategies through the adequate combination of available particle technologies and excipients. In so doing, the properties of PLGA particles can be finely tuned at micro-size and nano-size level to fulfill specific therapeutic needs. This means not only to realize optimal in vitro/in vivo lung deposition of the formulation, which is still crucial, but also to control the fate of the drug in the lung after particle landing.

Summary

Although many challenges still exist, PLGA carriers may be highly beneficial and present a new scenario for patients suffering from chronic lung diseases and for pharmaceutical companies working to develop novel inhaled products.

Alginate-hyaluronan composite hydrogels accelerate wound healing process

In this paper we propose polysaccharide hydrogels combining alginate (ALG) and hyaluronan (HA) as biofunctional platform for dermal wound repair. Hydrogels produced by internal gelation were homogeneous and easy to handle. Rheological evaluation of gelation kinetics of ALG/HA mixtures at different ratios allowed understanding the HA effect on ALG cross-linking process. Disk-shaped hydrogels, at different ALG/HA ratio, were characterized for morphology, homogeneity and mechanical properties. Results suggest that, although the presence of HA does significantly slow down gelation kinetics, the concentration of cross-links reached at the end of gelation is scarcely affected. The in vitro activity of ALG/HA dressings was tested on adipose derived multipotent adult stem cells (Ad-MSC) and an immortalized keratinocyte cell line (HaCaT). Hydrogels did not interfere with cell viability in both cells lines, but significantly promoted gap closure in a scratch assay at early (1 day) and late (5 days) stages as compared to hydrogels made of ALG alone (p<0.01 and 0.001 for Ad-MSC and HaCaT, respectively). In vivo wound healing studies, conducted on a rat model of excised wound indicated that after 5 days ALG/HA hydrogels significantly promoted wound closure as compared to ALG ones (p<0.001). Overall results demonstrate that the integration of HA in a physically cross-linked ALG hydrogel can be a versatile strategy to promote wound healing that can be easily translated in a clinical setting.

Microsphere-integrated collagen scaffolds for tissue engineering: Effect of microsphere formulation and scaffold properties on protein release kinetics

A promising approach to control the time and space distribution of signalling molecules inside tissue engineering scaffolds consists in entrapping biodegradable microspheres releasing the protein locally for long time frames. However, a rational design of microsphere-integrated scaffolds requires the knowledge of protein release profiles directly within the polymeric template. In this work, PLGA microspheres encapsulating rhodamine-labelled bovine serum albumin (BSA-Rhod) as a model protein were produced in different formulation conditions and tested for their release features in solution and in collagen and collagen/hyaluronic acid (HA) scaffolds. BSA-Rhod release profiles from single microspheres in solution and within the scaffold were assessed by using a confocal laser scanning microscopy (CLSM)-assisted method. Results suggest that the same diffusion-erosion process controls BSA-Rhod release from microspheres in solution and collagen. Nonetheless, two main factors contribute protein release within the scaffold, that is water activity in the release environment and transport properties of the protein in the gel. While microsphere formulation mainly controls the induction time necessary to activate protein release, polymer scaffold composition governs the release rate. Thus, the fine regulation of a tissue engineering construct may be obtained by an appropriate combination of microspheres and scaffolds, providing a spatial and temporal control over signalling molecule delivery.

Cyclodextrins in the production of large porous particles: Development of dry powders for the sustained release of insulin to the lungs

The aim of this work was to develop dry powders intended for insulin pulmonary delivery. To this purpose, large porous particles (LPP) made of poly(lactide-co-glycolide) (PLGA) were produced by the double emulsion-solvent evaporation technique. Hydroxypropyl-beta-cyclodextrin (HPbetaCD), also known as absorption enhancer for pulmonary protein delivery, was tested as aid excipient to optimize the aerodynamic behaviour of the microparticles. Several microsphere formulations, differing in HPbetaCD and insulin loadings, were produced and their properties compared. A contemporary release of insulin and HPbetaCD from the system can be achieved by selecting appropriate formulation conditions. HPbetaCD-containing LPP with flow properties and dimensions suitable for aerosolization and deposition in deep regions of the lung following inhalation were produced. In conclusion, the developed system turns to be of great potential for the combined delivery of the protein and the adsorption promoter in the respiratory tract.

Spectrophotometric determination of polyethylenimine in the presence of an oligonucleotide for the characterization of controlled release formulations

Polyethylenimine (PEI) is a cationic polymer that can be associated to oligonuclotides to promote their transfection both in vitro and in vivo. The controlled release of oligonucleotide/polyethylenimine complexes from biodegradable systems can result in an increased cellular internalisation of the oligonucleotide and a reduced cytotoxicity of the complex. This effect strongly depends on the amount of PEI loaded in and released from the delivery system. In this work we describe a rapid, sensitive and reproducible spectrophotometric method for the quantitative analysis of PEI by itself or in the presence of an associated oligonucleotide. PEI does not possess chromophores, hence the determination by ordinary spectrophotometry is not possible. However, upon addition of copper (II) ions, PEI forms a dark blue cuprammonium complex that can be detected by UV-vis spectrophotometry. The optimum conditions in terms of optical parameters, copper (II) concentration required for a quantitative PEI complexation, and the most suitable medium for the reaction were ascertained. A linear relationship (r(2)=0.9997) between absorbance and amounts of PEI was found at lambda(max) of 285 nm over the concentration range 5.0-50.0 microg ml(-1). The detection limit (QOD) was 4.0 microg ml(-1). The method was validated for the quantitation of PEI in the presence of an oligonucleotide, which absorbs at 285 nm as well.

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.

Feeding liquid, non-ionic surfactant and cyclodextrin affect the properties of insulin-loaded poly(lactide-co-glycolide) microspheres prepared by spray-drying

The potential of spray-drying technique for the encapsulation in poly(lactide-co-glycolide) (PLGA) microspheres of bovine insulin, a poorly stable peptide, has been investigated. Insulin-loaded microspheres were prepared by spray-drying different feeding liquids containing insulin and PLGA, that is a S/O dispersion, a W/O emulsion or an acetic acid solution. In the case of the emulsion, insulin was also co-encapsulated with either non-ionic surfactants such as polysorbate 20 and poloxamer 188, or complexing agents such as HPbetaCD. In the microspheres prepared from the acetic acid solution of insulin and PLGA, HPbetaCD was tested. Microspheres containing surfactants were aggregated, whereas good quality particles displaying a mean diameter in the range 12.1-27.9 microm were produced in the other cases. Insulin was efficiently loaded inside microspheres except for S/O formulation (only 22% of total insulin content was entrapped). The impact of the microencapsulation process on insulin chemical and conformational stability was assessed by HPLC, circular dichroism and turbidimetry studies. Under the adopted manufacture conditions, insulin was encapsulated in the native state and its chemical and conformational stability was preserved along the fabrication process. The formulations containing only insulin displayed low burst effects (6-11%), whereas the addition of surfactants resulted in much higher burst effects (49-54%) and faster release rate. The co-encapsulation of HPbetaCD slowed down the overall release rate and, in the case of microspheres prepared from the emulsion, allowed a constant insulin release up to 45 days. The study of insulin stability along the release phase showed that insulin was released in the intact form and un-released insulin was stable inside all the microsphere formulations. We conclude that insulin can be effectively encapsulated in PLGA microspheres by the spray-drying technique. Additives with complexing properties such as HPbetaCD have demonstrated a potential in optimizing the release rate of insulin when used in microspheres prepared from W/O emulsions.

How cyclodextrin incorporation affects the properties of protein-loaded PLGA-based microspheres: the case of insulin/hydroxypropyl-β-cyclodextrin system

The aim of this work was to study the influence of cyclodextrin (CD) incorporation on the properties of protein-loaded poly(lactide-co-glycolide) (PLGA) microspheres, with particular regards to protein release kinetics. To this purpose, insulin-loaded microspheres were prepared by spray-drying emulsion or solution formulations, with or without hydroxypropyl-beta-cyclodextrin (HPbetaCD), and fully characterized for encapsulation efficiency and release kinetics of both insulin and cyclodextrin. Homogeneous populations of spherical microparticles entrapping both insulin and HPbetaCD were obtained. In order to get an insight into insulin/HPbetaCD interactions occurring inside microspheres, Fourier transform infrared (FTIR) analysis in the Amide I region was performed. FTIR spectra of dried microspheres containing HPbetaCD showed a change in insulin secondary structure, attributed to the presence of insulin/HPbetaCD complexes within microspheres. Insulin release was affected by the presence of HPbetaCD depending on the initial formulation conditions. In the case of microspheres prepared from emulsion, cyclodextrin reduced only insulin burst, whereas in the case of microspheres obtained from solution, the overall insulin release rate was slowed down. Combining the release kinetics of HPbetaCD with the FTIR results on hydrated microspheres, it was concluded that the formation of insulin/HPbetaCD complexes inside microspheres is critical to decrease protein diffusivity in the polymer matrix and achieve an effective modulation of protein release rate.

Hyaluronan-decorated polymer nanoparticles targeting the CD44 receptor for the combined photo/chemo-therapy of cancer

In the attempt to develop novel concepts in designing targeted nanoparticles for combination therapy of cancer, we propose here CD44-targeted hyaluronan-decorated double-coated nanoparticles (dcNPs) delivering the lipophilic chemotherapeutic docetaxel (DTX) and an anionic porphyrin (TPPS₄). dcNPs are based on electrostatic interactions between a negative DTX-loaded nanoscaffold of poly(lactide-co-glycolide), a polycationic shell of polyethyleneimine entangling negatively-charged TPPS₄ and finally decorated with hyaluronan (HA) to promote internalization through CD44 receptor-mediated endocytosis. DTX/TPPS₄-dcNPs, prepared through layer-by-layer deposition, showed a hydrodynamic diameter of around 180 nm, negative zeta potential and efficient loading of both DTX and TPPS₄. DTX/TPPS₄-dcNPs were freeze-dried with trehalose giving a powder that could be easily dispersed in different media. Excellent stability of dcNPs in specific salt- and protein-containing media was found. Spectroscopic behavior of DTX/TPPS₄-dcNPs demonstrated a face-to-face arrangement of the TPPS₄ units in non-photoresponsive H-type aggregates accounting for an extensive aggregation of the porphyrin embedded in the shell. Experiments in MDA-MB-231 cells overexpressing the CD44 receptor demonstrated a 9.4-fold increase in the intracellular level of TPPS₄ delivered from dcNPs as compared to free TPPS₄. Light-induced death increased tremendously in cells that had been treated with a combination of TPPS₄ and DTX delivered through dcNPs as compared with free drugs, presumably due to efficient uptake and co-localization inside the cells. In perspective, the strategy proposed here to target synergistic drug combinations through HA-decorated nanoparticles seems very attractive to improve the specificity and efficacy of cancer treatment.

Toward Repositioning Niclosamide for Antivirulence Therapy of Pseudomonas aeruginosa Lung Infections: Development of Inhalable Formulations through Nanosuspension Technology

Inhaled antivirulence drugs are currently considered a promising therapeutic option to treat Pseudomonas aeruginosa lung infections in cystic fibrosis (CF). We have recently shown that the anthelmintic drug niclosamide (NCL) has strong quorum sensing (QS) inhibiting activity against P. aeruginosa and could be repurposed as an antivirulence drug. In this work, we developed dry powders containing NCL nanoparticles that can be reconstituted in saline solution to produce inhalable nanosuspensions. NCL nanoparticles were produced by high-pressure homogenization (HPH) using polysorbate 20 or polysorbate 80 as stabilizers. After 20 cycles of HPH, all formulations showed similar properties in the form of needle-shape nanocrystals with a hydrodynamic diameter of approximately 450 nm and a zeta potential of -20 mV. Nanosuspensions stabilized with polysorbate 80 at 10% w/w to NCL (T80_10) showed an optimal solubility profile in simulated interstitial lung fluid. T80_10 was successfully dried into mannitol-based dry powder by spray drying. Dry powder (T80_10 DP) was reconstituted in saline solution and showed optimal in vitro aerosol performance. Both T80_10 and T80_10 DP were able to inhibit P. aeruginosa QS at NCL concentrations of 2.5-10 μM. NCL, and these formulations did not significantly affect the viability of CF bronchial epithelial cells in vitro at microbiologically active concentrations (i.e., ≤10 μM). In vivo acute toxicity studies in rats confirmed no observable toxicity of the NCL T80_10 DP formulation upon intratracheal administration at a concentration 100-fold higher than the anti-QS activity concentration. These preliminary results suggest that NCL repurposed in the form of inhalable nanosuspensions has great potential for the local treatment of P. aeruginosa lung infections as in the case of CF patients.

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

Background

Novel 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.

Results

A 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.

Conclusions

Taken 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.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-015-0088-2) contains supplementary material, which is available to authorized users.

Hybrid Lipid/Polymer Nanoparticles for Pulmonary Delivery of siRNA: Development and Fate Upon In Vitro Deposition on the Human Epithelial Airway Barrier

BACKGROUND

Nowadays, the downregulation of genes involved in the pathogenesis of severe lung diseases through local siRNA delivery appears an interesting therapeutic approach. In this study, we propose novel hybrid lipid-polymer nanoparticles (hNPs) consisting of poly(lactic-co-glycolic) acid (PLGA) and dipalmitoyl phosphatidylcholine (DPPC) as siRNA inhalation system.

METHODS

A panel of DPPC/PLGA hNPs was prepared by emulsion/solvent diffusion and fully characterized. A combination of model siRNAs against the sodium transepithelial channel (ENaC) was entrapped in optimized hNPs comprising or not poly(ethylenimine) (PEI) as third component. siRNA-loaded hNPs were characterized for encapsulation efficiency, release kinetics, aerodynamic properties, and stability in artificial mucus (AM). The fate and cytotoxicity of hNPs upon aerosolization on a triple cell co-culture model (TCCC) mimicking human epithelial airway barrier were assessed. Finally, the effect of siRNA-loaded hNPs on ENaC protein expression at 72 hours was evaluated in A549 cells.

RESULTS

Optimized muco-inert hNPs encapsulating model siRNA with high efficiency were produced. The developed hNPs displayed a hydrodynamic diameter of ∼150 nm, a low polydispersity index, a negative ζ potential close to -25 mV, and a peculiar triphasic siRNA release lasting for 5 days, which slowed down in the presence of PEI. siRNA formulations showed optimal in vitro aerosol performance after delivery with a vibrating mesh nebulizer. Furthermore, small-angle X-ray scattering analyses highlighted an excellent stability upon incubation with AM, confirming the potential of hNPs for direct aerosolization on mucus-lined airways. Studies in TCCC confirmed that fluorescent hNPs are internalized inside airway epithelial cells and do not exert any cytotoxic or acute proinflammatory effect. Finally, a prolonged inhibition of ENaC protein expression was observed in A549 cells upon treatment with siRNA-loaded hNPs.

CONCLUSIONS

Results demonstrate the great potential of hNPs as carriers for pulmonary delivery of siRNA, prompting toward investigation of their therapeutic effectiveness in severe lung diseases.

Long-term release and improved intracellular penetration of oligonucleotide-polyethylenimine complexes entrapped in biodegradable microspheres

The aim of this work was to design a biodegradable delivery system for oligonucleotides providing both a sustained release and an improved intracellular penetration. To this purpose oligonucleotide/polyethylenimine (ON/PEI) complexes at nitrogen to phosphate (N/P) molar ratios of about 15 or 40 were encapsulated into poly(lactide-co-glycolide) microspheres by the multiple emulsion-solvent evaporation technique. ON/PEI complexes were efficiently entrapped inside microspheres. The introduction of salts within the external aqueous phase allowed an improvement of microsphere characteristics. In particular, the use of sodium chloride led to a reduced microsphere porosity and a more homogeneous ON distribution inside the polymeric matrix. These effects were attributed to the reduced flux of water from the external aqueous phase toward the internal aqueous droplets, due to the osmotic effect of sodium chloride. Both, the reduced porosity and the improved ON distribution inside the matrix, were considered responsible for the lower burst effect and the slower ON release rate from microsphere prepared with sodium chloride. ON/PEI complexes encapsulated inside microspheres were also protected toward enzymatic degradation in fetal calf serum. Interestingly, ON/PEI complexes slowly released from microspheres efficiently penetrated inside HeLa cells and oligonucleotides were preferentially located in the nucleus.

Hybrid Lipid/Polymer Nanoparticles to Tackle the Cystic Fibrosis Mucus Barrier in siRNA Delivery to the Lungs: Does PEGylation Make the Difference?

Inhaled siRNA therapy has a unique potential for treatment of severe lung diseases, such as cystic fibrosis (CF). Nevertheless, a drug delivery system tackling lung barriers is mandatory to enhance gene silencing efficacy in the airway epithelium. We recently demonstrated that lipid-polymer hybrid nanoparticles (hNPs), comprising a poly(lactic-co-glycolic) acid (PLGA) core and a lipid shell of dipalmitoyl phosphatidylcholine (DPPC), may assist the transport of the nucleic acid cargo through mucus-covered human airway epithelium. To study in depth the potential of hNPs for siRNA delivery to the lungs and to investigate the hypothesized benefit of PEGylation, here, an siRNA pool against the nuclear factor-κB (siNFκB) was encapsulated inside hNPs, endowed with a non-PEGylated (DPPC) or a PEGylated (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) or DSPE-PEG) lipid shell. Resulting hNPs were tested for their stability profiles and transport properties in artificial CF mucus, mucus collected from CF cells, and sputum samples from a heterogeneous and representative set of CF patients. Initial information on hNP properties governing their interaction with airway mucus was acquired by small-angle X-ray scattering (SAXS) studies in artificial and cellular CF mucus. The diffusion profiles of hNPs through CF sputa suggested a crucial role of lung colonization of the corresponding donor patient, affecting the mucin type and content of the sample. Noteworthy, PEGylation did not boost mucus penetration in complex and sticky samples, such as CF sputa from patients with polymicrobial colonization. In parallel, in vitro cell uptake studies performed on mucus-lined Calu-3 cells grown at the air-liquid interface (ALI) confirmed the improved ability of non-PEGylated hNPs to overcome mucus and cellular lung barriers. Furthermore, effective in vitro NFκB gene silencing was achieved in LPS-stimulated 16HBE14o- cells. Overall, the results highlight the potential of non-PEGylated hNPs as carriers for pulmonary delivery of siRNA for local treatment of CF lung disease. Furthermore, this study provides a detailed understanding of how distinct models may provide different information on nanoparticle interaction with the mucus barrier.

Enhancement of 5-FU sensitivity by the proapoptotic rpL3 gene in p53 null colon cancer cells through combined polymer nanoparticles

Colon cancer is one of the leading causes of cancer-related death worldwide and the therapy with 5-fluorouracil (5-FU) is mainly limited due to resistance. Recently, we have demonstrated that nucleolar stress upon 5-FU treatment leads to the activation of ribosome-free rpL3 (L3) as proapoptotic factor. In this study, we analyzed L3 expression profile in colon cancer tissues and demonstrated that L3 mRNA amount decreased with malignant progression and the intensity of its expression was inversely related to tumor grade and Bcl-2/Bax ratio. With the aim to develop a combined therapy of 5-FU plus plasmid encoding L3 (pL3), we firstly assessed the potentiation of the cytotoxic effect of 5-FU on colon cancer cells by L3. Next, 10 μM 5-FU and 2 μg of pL3 were encapsulated in biocompatible nanoparticles (NPs) chemically conjugated with HA to achieve active tumor-targeting ability in CD44 overexpressing cancer cells. We showed the specific intracellular accumulation of NPs in cells and a sustained release for 5-FU and L3. Analysis of cytotoxicity and apoptotic induction potential of combined NPs clearly showed that the 5-FU plus L3 were more effective in inducing apoptosis than 5-FU or L3 alone. Furthermore, we show that the cancer-specific chemosensitizer effect of combined NPs may be dependent on L3 ability to affect 5-FU efflux by controlling P-gp (P-glycoprotein) expression. These results led us to propose a novel combined therapy with the use of 5-FU plus L3 in order to establish individualized therapy by examining L3 profiles in tumors to yield a better clinical outcomes.

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

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.