Biodegradable Polymersomes as Nanocarriers for Doxorubicin Hydrochloride: Enhanced Cytotoxicity in MCF-7/ADR Cells and Prolonged Blood Circulation.

PURPOSE: DOX is one of the most potent anticancer drugs. But its short half-life and the occurrence of multi-drug resistance (MDR) markedly limit its clinical application. To solve these problems, we develop DOX loaded polymersomes (DOX polymersomes). METHODS: An methoxy poly(ethylene glycol)-b-poly(epsilon-caprolactone) (mPEG-b-PCL) copolymer was synthesized and used to prepare DOX polymersomes. The pharmaceutical properties of DOX polymersomes were characterized. The in vitro release profile of DOX from polymersomes was investigated. The in vitro cytotoxicity and cell uptake studies were performed on MCF-7 and MCF-7/ADR cells. The in vivo pharmacokinetic profiles were investigated on Sprague-Dawley rats. RESULTS: DOX polymersomes had a nano-scale particle size of about 60 nm with a hydrophobic membrane about 10 nm in thickness. Release of DOX from the polymersomes took place in a sustained manner. Cell experiments showed DOX polymersomes enhanced the cytotoxicity and the intracellular accumulation of DOX in MCF-7/ADR cells, compared with free DOX. In vivo pharmacokinetic study showed the DOX polymersomes increased the bioavailability and prolonged the circulation time in rats. CONCLUSIONS: The entrapment of DOX in biodegradable polymersomes could enhance cytotoxicity in MCF-7/ADR cells and improve its in vivo pharmacokinetic profile.

Membrane-Loaded Doxorubicin Liposomes Based on Ion-Pairing Technology with High Drug Loading and pH-Responsive Property.

In order to achieve high drug loading and high entrapment efficiency, a doxorubicin-cholesteryl hemisuccinate ion-pair complex (DCHIP) was formed, and the ion-pair complex liposomes (DCHIP-Lip) were prepared based on conventional thin-film dispersion method. Firstly, DCHIP was fabricated and confirmed with FTIR, 1H-NMR, DSC, and XRD techniques. Afterwards, DCHIP-Lip were prepared and evaluated in terms of particle size, zeta potential, entrapment efficiency, and drug loading content. Finally, the in vitro and in vivo behavior of liposomes was further investigated. The DCHIP-Lip had a nanoscale particle size of about 120 nm with a negative zeta potential of about -22 mV. In addition, the entrapment efficiency and drug loading content of DOX reached 6.4 ± 0.05 and 99.29 ± 0.3%, respectively. Importantly, the release of DCHIP-Lip was pH sensitive and increased cell toxicity against MCF-7 cells was achieved. Upon dilution, the liposomes were fairly stable under physiological conditions. The in vivo pharmacokinetic study indicated that the AUC of DOX in DCHIP-Lip was 11.48-fold higher than that of DOX-HCl solution and the in vivo antitumor activity of DCHIP-Lip showed less body weight loss and a significant prohibition effect of tumor growth. Based on these findings, it can be seen that the ion-pairing technology combined with conventional liposome drug loading method could be used to achieve high drug loading and it could be valuable for the study of liposomal delivery system.

Humid Heat Autoclaving of Hybrid Nanoparticles Achieved by Decreased Nanoparticle Concentration and Improved Nanoparticle Stability Using Medium Chain Triglycerides as a Modifier.

PURPOSE: Humid heat autoclaving is a facile technique widely used in the sterilization of injections, but the high temperature employed would destroy nanoparticles composed of biodegradable polymers. The aim of this study was to investigate whether incorporation of medium chain triglycerides (MCT) could stabilize nanoparticles composed of poly (ethylene glycol)-b-polycaprolactone (PEG-b-PCL) during autoclaving (121°C, 10 min). METHODS: Polymeric nanoparticles with different MCT contents were prepared by dialysis. Block copolymer degradation was studied by GPC. The critical aggregation concentrations of nanoparticles at different temperatures were determined using pyrene fluorescence. The size, morphology and weight averaged molecular weight of pristine/autoclaved nanoparticles were studied using DLS, TEM and SLS, respectively. Drug loading content and release profile were determined using RP-HPLC. RESULTS: The protecting effect of MCT on nanoparticles was dependent on the amount of MCT incorporated. Nanoparticles with high MCT contents, which assumed an emulsion-like morphology, showed reduced block copolymer degradation and particle disassociation after incubation at 100°C for 24 h. Nanoparticles with high MCT content showed the lowest critical aggregation concentration (CAC) under either room temperature or 60°C and the lowest particle concentration among all samples. And the particle size, drug loading content, physical stability and release profile of nanoparticles with high MCT contents remained nearly unchanged after autoclaving. CONCLUSION: Incorporation of high amount of MCT changed the morphology of PEG-b-PCL based nanoparticles to an emulsion-like structure and the nanoparticles prepared could withstand autoclaving due to improved particle stability and decreased particle concentration caused by MCT incorporation.

Cysteine-Functionalized Nanostructured Lipid Carriers for Oral Delivery of Docetaxel: A Permeability and Pharmacokinetic Study.

Here we report the development and evaluation of cysteine-modified nanostructured lipid carriers (NLCs) for oral delivery of docetaxel (DTX). The NLCs ensure high encapsulation efficiency of docetaxel, while the cysteine bound the NLCs with PEG2000-monostearate (PEG2000-MSA) as a linker, and allowed a specific interaction with mucin of the intestinal mucus layer and facilitated the intestinal transport of docetaxel. The cysteine-modified NLCs (cNLCs) had a small particle size (<100 nm) and a negative zeta potential (-13.72 ± 0.07 mV), which was lower than that of the unmodified NLCs (uNLCs) (-6.39 ± 0.07 mV). This correlates well with the location of the cysteine group on the surface of the NLCs obtained by X-ray photoelectron spectroscopy (XPS). The cNLCs significantly improved the mucoadhesion properties compared with uNLCs. The intestinal absorption of cNLCs in total intestinal segments was greatly improved in comparison with uNLCs and docetaxel solution (DTX-Sol), and the in vivo imaging system captured pictures also showed not only increased intestinal absorption but also improved accumulation in blood. The cNLCs could be absorbed into the enterocytes via both endocytosis and passive transport. The results of the in vivo pharmacokinetic study indicated that the AUC0-t of cNLCs (1533.00 ng/mL·h) was markedly increased 12.3-fold, and 1.64-fold compared with docetaxel solution and uNLCs, respectively. Overall, the cysteine modification makes nanostructured lipid carriers more suitable as nanocarriers for oral delivery of docetaxel.

Decreased Core Crystallinity Facilitated Drug Loading in Polymeric Micelles without Affecting Their Biological Performances.

Cargo-loading capacity of polymeric micelles could be improved by reducing the core crystallinity and the improvement in the amount of loaded cargo was cargo-polymer affinity dependent. The effect of medium chain triglyceride (MCT) in inhibiting PCL crystallization was confirmed by DSC and polarized microscope. When incorporating MCT into polymeric micelles, the maximum drug loading of disulfiram (DSF), cabazitaxel (CTX), and TM-2 (a taxane derivative) increased from 2.61 ± 0.100%, 13.5 ± 0.316%, and 20.9 ± 1.57% to 8.34 ± 0.197%, 21.7 ± 0.951%, and 28.0 ± 1.47%, respectively. Moreover, the prepared oil-containing micelles (OCMs) showed well-controlled particle size, good stability, and decreased drug release rate. MCT incorporation showed little influence on the performances of micelles in cell studies or pharmacokinetics. These results indicated that MCT incorporation could be a core construction module applied in the delivery of hydrophobic drugs.

Phytochemistry and Pharmacological Activities of Wolfiporia cocos (F.A. Wolf) Ryvarden & Gilb.

Poria cocos is the dried sclerotium of Wolfiporia cocos (F.A. Wolf) Ryvarden & Gilb., which was the current accepted name and was formerly known as Macrohyporia cocos (Schwein.) I. Johans. & Ryvarden, Pachyma cocos (Schwein.) Fr., Poria cocos F.A. Wolf and Sclerotium cocos Schwein. It is one of the most important crude drugs in traditional Chinese medicine, with a wide range of applications in ameliorating phlegm and edema, relieving nephrosis and chronic gastritis and improving uneasiness of minds. Its extensive pharmacological effects have attracted considerable attention in recent years. However, there is no systematic review focusing on the chemical compounds and pharmacological activities of Poria cocos. Therefore, this review aimed to provide the latest information on the chemical compounds and pharmacological effects of Poria cocos, exploring the therapeutic potential of these compounds. We obtained the information of Poria cocos from electronic databases such as SCI finder, PubMed, Web of Science, CNKI, WanFang DATA and Google Scholar. Up to now, two main active ingredients, triterpenes and polysaccharides of Poria cocos, have been identified from Poria cocos. It has been reported that they have pharmacological effects on anti-tumor, anti-bacterial, anti-oxidant, anti-inflammatory, immunomodulation, and liver and kidney protection. The review summarizes the phytochemistry and pharmacological properties of Poria cocos, which suggest that researchers should focus on the development of new drugs about Poria cocos to make them exert greater therapeutic potential.

The promoting effect of enteric materials on the oral absorption of larotaxel-loaded polymer-lipid hybrid nanoparticles.

Enteric polymers have been found with absorption promotion effect on nanoparticles. To study the role of enteric polymers played in the process of oral nanoparticle delivery, Eudragit L100-55 (EU) and sodium alginate (SA) were selected as model enteric polymers and larotaxel (LTX) as model drug. Suspensions composed of LTX-loaded nanoparticles, HPMC and different enteric polymers (EU and SA) were prepared (NP@EU, NP@SA). And aspects like precipitate morphology upon contact with acid, nanoparticle encapsulation capability, in vitro drug release, intestinal residence and in vivo oral bioavailability were studied. It was found that precipitates formed by EU could encapsulate more NP in acidic environment than those of SA (>95% of EU vs. approximately 70% of SA), and this difference in NP encapsulation was found correlated with the morphology of the precipitates formed: precipitates of EU appeared as three dimensional granules with dense inner structure, while SA precipitated into film-like porous structures. Results of pharmacokinetic study indicated that both EU and SA were capable in improving LTX absorption with absolute bioavailability of 77.1% and 42.5%, respectively. And the better absorption promoting effect of NP@EU was correlated with its longer intestinal residence shown by the results of ex vivo imaging study. In conclusion, both EU and SA could improve the oral bioavailability of LTX-loaded NP, and NP encapsulation capability and intestinal residence time are considered as key factors affecting the degree of absorption promotion.

Strategies for improving the payload of small molecular drugs in polymeric micelles.

In the past few years, substantial efforts have been made in the design and preparation of polymeric micelles as novel drug delivery vehicles. Typically, polymeric micelles possess a spherical core-shell structure, with a hydrophobic core and a hydrophilic shell. Consequently, poorly water-soluble drugs can be effectively solubilized within the hydrophobic core, which can significantly boost their drug loading in aqueous media. This leads to new opportunities for some bioactive compounds that have previously been abandoned due to their low aqueous solubility. Even so, the payload of small molecular drugs is still not often satisfactory due to low drug loading and premature release, which makes it difficult to meet the requirements of in vivo studies. This problem has been a major focus in recent years. Following an analysis of the published literature in this field, several strategies towards achieving polymeric micelles with high drug loading and stability are presented in this review, in order to ensure adequate drug levels reach target sites.

Improved tumor tissue penetration and tumor cell uptake achieved by delayed charge reversal nanoparticles.

The high affinity of positively charged nanoparticles to biological interfaces makes them easily taken up by tumor cells but limits their tumor permeation due to non-specific electrostatic interactions. In this study, polyion complex coated nanoparticles with different charge reversal profiles were developed to study the influence of charge reversal profile on tumor penetration. The system was constructed by polyion complex coating using micelles composed of poly (lysine)-b-polycaprolactone (PLys-b-PCL) as the cationic core and poly (glutamic acid)-g- methoxyl poly (ethylene glycol) (PGlu-g-mPEG) as the anionic coating material. Manipulation of charge reversal profile was achieved by controlling the polymer chain entanglement and electrostatic interaction in the polyion complex layer through glutaraldehyde-induced shell-crosslinking. The delayed charge reversal nanoparticles (CTCL30) could maintain negatively charged in pH 6.5 PBS for at least 2h and exhibit pH-responsive cytotoxicity and cellular uptake in an extended time scale. Compared with a faster charge reversal counterpart (CTCL70) with similar pharmacokinetic profile, CTCL30 showed deeper penetration, higher in vivo tumor cell uptake and stronger antitumor activity in vivo (tumor inhibition rate: 72.3% vs 60.2%, compared with CTCL70). These results indicate that the delayed charge reversal strategy could improve therapeutic effect via facilitating tumor penetration. STATEMENT OF SIGNIFICANCE: Here, the high tumor penetration capability of PEG-coated nanoparticles and the high cellular uptake of cationic nanoparticles were combined by a delayed charge reversal drug delivery system. This drug delivery system was composed of a drug-loading cationic inner core and a polyion complex coating. Manipulation of charge reversal profile was realized by varying the crosslinking degree of the shell of the cationic inner core, through which changed the strength of the polyion complex layer. Nanoparticles with delayed charge reversal profile exhibited improved tumor penetration, in vivo tumor cell uptake and in vivo tumor growth inhibition effect although they have similar pharmacokinetic and biodistribution behaviors with their instant charge reversal counterpart.