Influence of drug-carrier compatibility and preparation method on the properties of paclitaxel-loaded lipid liquid crystalline nanoparticles

Evaluation of cell membrane-derived nanoparticles as therapeutic carriers for pancreatic ductal adenocarcinoma using an in vitro tumour stroma model

Here, we fabricated nanoparticles made solely from the membrane of cells found in the pancreatic tumour's microenvironment (TME), like the human MiaPaCa-2 cells and M2-polarized macrophages. The cell membrane-derived nanoparticles (CMNPs) deriving from the MiaPaCa-2 cells (MPC2-CMNPs) were loaded with the chemotherapeutic drug paclitaxel (PTX), and the CMNPs deriving from M2-polarized macrophages (M2-CMNPs) were loaded with the colony-stimulating factor 1 receptor inhibitor, pexidartinib (PXDB). The CMNPs' thorough morphological and physicochemical characterisation was followed by an in-depth study of their targeting ability and the endocytosis pathway involved during their internalisation. An in vitro model of the desmoplastic stroma comprising cancer-associated fibroblast-mimicking cells and M2-polarized macrophages was also developed. The model was characterised by collagen and α-smooth muscle actin (α-SMA) expression (overexpressed in desmoplasia) and was used to assess the CMNPs' ability to cross the stroma and target the tumour cells. Moreover, we assessed the effect of PXDB-loaded M2-CMNPs on the expression of M1 (CD80/CD86) and M2 (CD206/CD209) polarisation markers on activated macrophages. Finally, we evaluated the PTX and PXDB-loaded CMNPs' effect on the viability of all the used TME cell lines alone or in combination. Overall, this pilot study showed the potential of the CMNPs to cross an in vitro stroma model and act synergistically to treat PDAC.

Lipidic lyotropic liquid crystals: Insights on biomedical applications

Liquid crystals (LCs) possess unique physicochemical properties, translatable into a wide range of applications. To date, lipidic lyotropic LCs (LLCs) have been extensively explored in drug delivery and imaging owing to the capability to encapsulate and release payloads with different characteristics. The current landscape of lipidic LLCs in biomedical applications is provided in this review. Initially, the main properties, types, methods of fabrication and applications of LCs are showcased. Then, a comprehensive discussion of the main biomedical applications of lipidic LLCs accordingly to the application (drug and biomacromolecule delivery, tissue engineering and molecular imaging) and route of administration is examined. Further discussion of the main limitations and perspectives of lipidic LLCs in biomedical applications are also provided. STATEMENT OF SIGNIFICANCE: Liquid crystals (LCs) are those systems between a solid and liquid state that possess unique morphological and physicochemical properties, translatable into a wide range of biomedical applications. A short description of the properties of LCs, their types and manufacturing procedures is given to serve as a background to the topic. Then, the latest and most innovative research in the field of biomedicine is examined, specifically the areas of drug and biomacromolecule delivery, tissue engineering and molecular imaging. Finally, prospects of LCs in biomedicine are discussed to show future trends and perspectives that might be utilized. This article is an ampliation, improvement and actualization of our previous short forum article "Bringing lipidic lyotropic liquid crystal technology into biomedicine" published in TIPS.

Micro- and nanoformulations of paclitaxel based on micelles, liposomes, cubosomes, and lipid nanoparticles: Recent advances and challenges

The diterpenoid molecule paclitaxel (PTX), extracted from the Western yew tree, Taxus brevifolia, is a promising anticancer drug specifically in clinical use for ovarian and breast cancers. However, its wider use is hampered by adverse effects and emerging resistance in cancer cells. Micelles, liposomes, cubosomes, and lipid nanoparticles (LNPs) have the potential to reduce or even remove complications associated with the use of PTX. Herein, we provide an overview of micro- and nanoformulations of PTX based on micelles, liposomes, cubosomes and LNPs to improve the therapeutic effects of this drug both in vitro and in vivo.

Controlling the pH dependent transition between monoolein Fd3m micellar cubosomes and hexosomes using fatty acetate and fatty acid additive mixtures

HYPOTHESIS

Cubosomes made from the inverse micellar cubic mesophase (I₂) with Fd3m symmetry possess a unique structure of closely packed inverse micelles. These have prospective functionality in sustained drug release. In this study, we hypothesised that similar to fatty acids, various fatty acetate compounds can induce the formation of micellar Fd3m cubosomes in monoolein (MO) nanoparticles. They are different to micellar cubosomes made of MO and a fatty acid, which are pH responsive and can transition from an Fd3m phase to an inverse hexagonal phase (H₂) as pH increases. We hypothesised that by co-doping a fatty acetate and fatty acid into MO, precise control of the Fd3m-H₂ phase transition pH in nanoparticles can be achieved.

EXPERIMENTS

Five unsaturated fatty acetates with hydrocarbon chain lengths between 18 and 24 were added to MO at a weight ratio of 0.45 - 0.60 to form nanoparticles. The nanoparticles were prepared using high-throughput formulation and characterised with synchrotron small angle X-ray scattering (SAXS). MO nanoparticles doped with vaccenyl acetate and vaccenic acid were used to demonstrate the fine control over Fd3m-H₂ phase transition pH.

FINDINGS

Micellar cubosomes (Fd3m phase) were found in MO nanoparticles doped with fatty acetates. The Fd3m structure was stable in a wide pH range of 2.6 - 8 and at temperatures up to 45 °C. In MO nanoparticles doped with the acetate/acid mixture, the Fd3m-H₂ phase transition pH was tuned between pH 5 and pH 7 by adjusting the ratio of vaccenyl acetate and vaccenic acid. As a H₂ phase generally offers faster drug release than an Fd3m phase, the pH responsive lipid nanoparticles developed here may find application in orally administrated formulation, where the vehicles must pass a low pH environment in the stomach before reaching neutral pH in the blood.

Novel Amphiphilic Block Copolymers for the Formation of Stimuli-Responsive Non-Lamellar Lipid Nanoparticles

Non-lamellar lyotropic liquid crystalline (LLC) lipid nanoparticles contain internal multidimensional nanostructures such as the inverse bicontinuous cubic and the inverse hexagonal mesophases, which can respond to external stimuli and have the potential of controlling drug release. To date, the internal LLC mesophase responsiveness of these lipid nanoparticles is largely achieved by adding ionizable small molecules to the parent lipid such as monoolein (MO), the mixture of which is then dispersed into nanoparticle suspensions by commercially available poly(ethylene oxide)-poly(propylene oxide) block copolymers. In this study, the Reversible Addition-Fragmentation chain Transfer (RAFT) technique was used to synthesize a series of novel amphiphilic block copolymers (ABCs) containing a hydrophilic poly(ethylene glycol) (PEG) block, a hydrophobic block and one or two responsive blocks, i.e., poly(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl acrylate) (PTBA) and/or poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA). High throughput small angle X-ray scattering studies demonstrated that the synthesized ABCs could simultaneously stabilize a range of LLC MO nanoparticles (vesicles, cubosomes, hexosomes, inverse micelles) and provide internal particle nanostructure responsiveness to changes of hydrogen peroxide (H2O2) concentrations, pH and temperature. It was found that the novel functional ABCs can substitute for the commercial polymer stabilizer and the ionizable additive in the formation of next generation non-lamellar lipid nanoparticles. These novel formulations have the potential to control drug release in the tumor microenvironment with endogenous H2O2 and acidic pH conditions.