Sustained delivery of cytarabine-loaded vesicular phospholipid gels for treatment of xenografted glioma

Preparation of Nanosized Pharmaceutical Formulations by Dual Centrifugation

Dual centrifugation (DC) is an innovative in-vial homogenization and in-vial nanomilling technique that has been in use for the preparation of liposomes for more than one decade. Since then, DC has continuously been developed for preparing various liposomes and other lipid nanoparticles including emulsions and solid lipid nanoparticles (SLNs) as well as polymersomes and nanocrystals. Improvements in equipment technology have been achieved over the past decade, so that DC is now on its way to becoming the quasi-standard for the simple, fast, and aseptic production of lipid nanoparticles and nanocrystals in small and medium batch sizes, including the possibility of simple and fast formulation screening or bedside preparations of therapeutic nanoparticles. More than 68 publications in which DC was used to produce nanoparticles have appeared since then, justifying an initial review of the use of DC for pharmaceutical nanotechnology.

Recent advances in lipid-based long-acting injectable depot formulations

Long-acting injectable (LAIs) delivery systems sustain the drug therapeutic action in the body, resulting in reduced dosage regimen, toxicity, and improved patient compliance. Lipid-based depots are biocompatible, provide extended drug release, and improve drug stability, making them suitable for systemic and localized treatment of various chronic ailments, including psychosis, diabetes, hormonal disorders, arthritis, ocular diseases, and cancer. These depots include oil solutions, suspensions, oleogels, liquid crystalline systems, liposomes, solid lipid nanoparticles, nanostructured lipid carriers, phospholipid phase separation gel, vesicular phospholipid gel etc. This review summarizes recent advancements in lipid-based LAIs for delivering small and macromolecules, and their potential in managing chronic diseases. It also provides an overview of the lipid depots available in market or clinical phase, as well as patents for lipid-based LAIs. Furthermore, this review critically discusses the current scenario of using in vitro release methods to establish IVIVC and highlights the challenges involved in developing lipid-based LAIs.

In vitro evaluation of copper sulfide nanoparticles decorated with folic acid/chitosan as a novel pH-sensitive nanocarrier for the efficient controlled targeted delivery of cytarabine as an anticancer drug

Nanoparticles (NPs) have gained more attention as drug delivery systems. Folic acid (FA)-chitosan (CS) conjugates, because of their biodegradability, low toxicity, and better stability, offer a pharmaceutical drug delivery tool. The aim of this work was to fabricate CuS NPs modified by CS followed by grafting FA as a nanocarrier for the delivery of cytarabine (CYT) as an anticancer drug. In this work, CuS NPs modified by CS and FA were successfully synthesized. The structural properties of the nanocarrier were characterized by using scanning electron microscopy, Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, and Brunauer-Emmett-Teller. The adsorption mechanism of CYT by adsorption isotherms, kinetics, and thermodynamics was deliberated and modeled. The in vitro CYT release behavior for the nanocarrier was 99% and 61% at pH 5.6 and 7.4, respectively. The adsorption behavior of CYT by CuS NP_s -CS-FA was well explored by pseudo-second-order kinetic and Langmuir isotherm models by the coefficient of determination (R² > 0.99). Thermodynamic results showed that the uptake of CYT by CuS NPs-CS-FA was endothermic and spontaneous. The experimental results showed that CYT/CuS NP_s -CS-FA can be proposed as an efficient nanocarrier for the targeted delivery of anticancer drugs.

Chlorogenic acid sustained-release gel for treatment of glioma and hepatocellular carcinoma

Chlorogenic acid (CGA) may provide an effective and safe option for tumor treatment. However, its application is limited because of short residence time in vivo and repeated administration required. A phospholipid-based in situ gel containing chlorogenic acid (CGA PG) was prepared via a simple way. The CGA PG exhibited good fluidity, easy injectability, high-drug-loading capacity, and suitable sustained-release behavior whether in vitro or in vivo. Furthermore, CGA PG could suppress tumor growth with no significant side effects. Overall, CGA PG may be a promising sustained drug delivery system with excellent therapeutic effect on glioma and hepatocellular carcinoma.

Evaluation of hepatic drug-metabolism for glioblastoma using liver-brain chip

Glioma is one of the most aggressive and highly fatal diseases with an extremely poor prognosis. Considering the poor clinical response to therapy in glioma, it is urgent to establish an in vitro model to facilitate the screening and assessment of anti-brain-tumor drugs. The blood-brain barrier (BBB), as well as liver metabolism plays an important role in determining the pharmacological activity of many anti-brain-tumor drugs. In this work, we designed a multi-interface liver-brain chip integrating co-culture system to assess hepatic metabolism dependent cytotoxicity of anti-brain-tumor drug in vitro. This microdevice composed of three microchannels which were separated by porous membrane and collagen. HepG2 and U87 cells were cultured in separated channels as mimics of liver and glioblastoma. Brain microvascular endothelial cells (BMECS) and cerebral astrocytes were co-cultured on collagen to mimic the brain microvascular endothelial barrier. Three common anti-tumor drugs, paclitaxel (PTX), capecitabine (CAP) and temozolomide (TMZ), were evaluated on this chip. In integrated liver-brain chip, liver enhanced the cytotoxicity of CAP on U87 cells by 30%, but having no significant effect on TMZ. The BBB decreased the cytotoxicity of PTX by 20%, while no significant effects were observed on TMZ and CAP, indicating the importance of liver metabolism and blood-brain barrier on the evaluation of anti-brain-tumor drugs. This work provides a biomimetic liver-brain model to mimic the physiological and pharmacological processes in vitro and presents a simple platform for long-term cell co-culture, drug delivery and metabolism, and real-time analysis of drug effects on brain cancer.

Cationic/Anionic Polyelectrolyte (PLL/PGA) Coated Vesicular Phospholipid Gels (VPGs) Loaded with Cytarabine for Sustained Release and Anti-glioma Effects

Background

Cationic and anionic polymer-modified nanoparticles offer promising properties for the drug and gene delivery. Our study uses cationic/anionic polyelectrolyte coated vesicular phospholipid gels (VPGs) loaded with cytarabine (Ara-C) that enhance in vitro and in vivo anti-glioma effects.

Methods

Sodium cholesteryl sulfate (SCS) or octadecylamine (ODA) incorporated in a phospholipids phase were used to prepare charged VPGs, and cationic ε-polylysine (PLL) coated VPGs (PLL-SCS VPGs) and anionic γ-polyglutamic acid (PGA) coated VPGs (PGA-ODA VPGs) were prepared via electrostatic interactions, respectively. The morphology, particle size, zeta potential, rheology properties, and in vitro release were then characterized. The in vitro cytotoxicity and cellular uptake were evaluated on U87-MG glioma cells. The in vivo antitumor effects were studied on BALB/c nude mice bearing a right flank U87-MG glioma model.

Results

The TEM images and physicochemical properties of cationic/anionic polyelectrolyte coated VPGs exhibited that polymers covered on the vesicular surface. The results of rheologic property analysis showed that cationic/anionic polyelectrolyte coated VPGs enhanced the viscosity of uncoated VPGs. The in vitro release experiments revealed that cationic/anionic polyelectrolyte coated VPGs kept Ara-C sustained release up to 18 days. Specially, compared with PLL-SCS VPGs, PGA-ODA VPGs demonstrated higher in vitro cytotoxicity and cellular uptake efficiency in U87-MG glioma cells, and enhanced in vivo antitumor effects when subcutaneously injected around the tumor. No severe toxicity appeared in the right flank U87-MG glioma model of BALB/c nude mice.

Conclusion

Anionic γ-PGA coated VPGs were superior to cationic PLL coated VPGs in terms of improving the anti-glioma effect for local delivery.

The Extracellular Matrix and Biocompatible Materials in Glioblastoma Treatment

During cancer genesis, the extracellular matrix (ECM) in the human brain undergoes important transformations, starting to resemble embryonic brain cell milieu with a much denser structure. However, the stiffness of the tumor ECM does not preclude cancer cells from migration. The importance of the ECM role in normal brain tissue as well as in tumor homeostasis has engaged much effort in trials to implement ECM as a target and an instrument in the treatment of brain cancers. This review provides a detailed analysis of both experimental and applied approaches in combined therapy for gliomas in adults. In general, matrix materials for glioma treatment should have properties facilitating the simplest delivery into the body. Hence, to deliver an artificial implant directly into the operation cavity it should be packed into a gel form, while for bloodstream injections matrix needs to be in the form of polymer micelles, nanoparticles, etc. Furthermore, the delivered material should mimic biomechanical properties of the native tissue, support vital functions, and slow down or stop the proliferation of surrounding cells for a prolonged period. The authors propose a two-step approach aimed, on the one hand, at elimination of remaining cancer cells and on the other hand, at restoring normal brain tissue. Thereby, the first bioartificial matrix to be applied should have relatively low elastic modulus should be loaded with anticancer drugs, while the second material with a higher elastic modulus for neurite outgrowth support should contain specific factors stimulating neuroregeneration.

Do interactions between protein and phospholipids influence the release behavior from lipid-based exenatide depot systems?

The release mechanism for proteins and peptides from vesicular phospholipid gels (VPGs) is very complex. Drug release proceeds via a combination of erosion of the gel and diffusion of the drug out of it. This diffusion can be retarded by a slow permeation of the drug across the lipid bilayers in the gel as well as by its direct binding or adsorption to the lipid bilayers. Finally, the viscosity and homogeneity of the formulation may affect the release behavior. So far a direct correlation between one of these parameters and the release kinetics is not possible. In the present study, we aimed to investigate the contribution of drug-membrane interactions to the release kinetics of exenatide from differently composed VPGs (POPC, POPG and mixtures of both). To this end, in vitro release of exenatide as well as in vitro release of the phospholipids was monitored. Binding affinities were determined by microscale thermophoresis (MST). The sustained release behavior of exenatide could not simply be correlated to high viscosity of the VPG formulation. Release of exenatide from VPGs of anionic membranes containing POPG proceeded with a half-life of the order of 5 days and it seems to be controlled by the erosion of the gel. Its rate is unaffected by the initial pH inside the gel, independently of the strong impact of pH on exenatide binding to the membrane. At pH 4.5, exenatide is cationic and binds to membranes containing anionic POPG with a high affinity (K_d ≈ 10-30 µM). No high affinity membrane binding of exenatide is detected in this at pH 7.4, where exenatide is anionic, and to zwitterionic membranes composed of POPC. Exenatide release from the latter has a significantly longer half-life of 30 to 55 days. That means, these VPGs are much more resistant to erosion and show a very slow diffusional release. In this case, diffusion should be slowed down by the barrier function of the membranes rather than membrane affinity. In conclusion, erosion of the VPG matrix and membrane permeability of the drug are the major parameters influencing the release of exenatide from VPGs of POPC-POPG, whereas drug binding to the membranes had a minor effect only.

Vesicular phospholipid gels as drug delivery systems for small molecular weight drugs, peptides and proteins: State of the art review

Lipid-based drug delivery has been investigated for a long time when it comes to liposomes and solid-lipid implants or solid-lipid nanoparticles. The promising, characteristic properties of these systems have led to the development of newer lipid-based drug delivery systems for the sustained release of drugs like liposomes for sustained delivery of substances, DepoFoam™ technology, phospholipid-based phase separation gels and vesicular phospholipid gels. Vesicular phospholipid gels (VPGs) are highly concentrated, viscous dispersions of high amounts of phospholipids in aqueous drug solution. The easy, solvent-free manufacturing process, high biocompatibility and various applications, as depot formulation for the sustained delivery of drugs and as a storage form of small unilamellar vesicles make VPGs highly attractive as drug carriers. Over the last years, the solvent free preparation process has advanced from high pressure homogenization to dual centrifugation (DC). Thereby a very simple one step process has been established for the preparation of VPGs. The semisolid VPG was first described in 1997 by Brandl et al. Since then, many formulations have been developed, encapsulating small molecular weight drugs like 5-FU (2003), cetrorelix (2005), cytarabine (2012) and exenatide (2015). In 2010, the first pharmaceutical protein, erythropoietin, was encapsulated in VPGs and sustained release of the substance was shown in vitro. In 2015, G-CSF was encapsulated in VPGs and tested in vivo for rotator cuff repair in a rat model and for PEGylated IFN-β-1b sustained release from vesicular phospholipid gels was demonstrated in vitro. Further, a very elegant administration technique for VPGs via needle-free injection was established. However this promising drug delivery system does still leave space for improvement and optimization. This review summarizes information about lipid-based depot systems in general and focuses on the historical development of VPGs. It emphasizes the advantages and drawbacks of VPGs as drug delivery device. Additionally, novel preparation methods and applications of VPGs will be discussed. A focus will be set on delivery of pharmaceutical proteins and peptides.

New pH-responsive gemini lipid derived co-liposomes for efficacious doxorubicin delivery to drug resistant cancer cells

A new pH-sensitive co-liposomal formulation was developed which could efficiently transport doxorubicin across the DOX-resistant cancer cells.

Resveratrol loaded PLGA:d-α-tocopheryl polyethylene glycol 1000 succinate blend nanoparticles for brain cancer therapy

The systemic circulation time and biological half-life of trans-Resveratrol (RSV) is enhanced using poly(d,l-lactide-co-glycolide)–d-α-tocopheryl polyethylene glycol 1000 succinate blend nanoparticles (RSV-PLGA-BNPs).

In vitro and in vivo sustained release of exenatide from vesicular phospholipid gels for type II diabetes

Diabetes is a chronic disease that requires daily treatment to maintain a stable blood glucose level. Sustained-release formulations can thus benefit the treatment of diabetes by reducing the repeated administration of therapeutics. Our study aimed to develop a sustained-release platform for exenatide that is biocompatible and capable of mass production. Vesicular phospholipid gels (VPGs) are semisolid phospholipid dispersions with controlled release profiles. Exenatide-VPGs prepared via simple magnetic stirring showed excellent biocompatibility with an average particle size of about 15 μm after redispersion. VPGs were shown to achieve sustained release for up to 21 days in vitro with no obvious burst effect. The in vivo release study showed that VPGs sustained the release of the exenatide for up to 11 days. Moreover, after subcutaneous injection of the exenatide-VPGs in the diabetic rats, the hypoglycemic effect lasted for 10 days compared with exenatide solution. In sum, the exenatide-VPGs system represents a promising sustained-release formulation for exenatide with a long-acting therapeutic efficacy in vivo.

Co-encapsulation of borneol and paclitaxel by liprosomes improved anti-tumor effect in a xenografted glioma model

In this study, a borneol (BOR) and paclitaxel (PTX) co-encapsulated lipid–protein nanocomplex (BP–liprosome) was developed for the treatment of brain glioma.