A cellular uptake of cis-platinum-encapsulating liposome through endocytosis by human neuroblastoma cell

Preparation and Antiproliferative Activity of Liposomes Containing a Combination of Cisplatin and Procainamide Hydrochloride

We have previously reported the enhancement of the antiproliferative and apoptotic activities of cis-diamminedichloroplatinum(II) (DDP) when it is coadministered with a class I antiarrhythmic drug procainamide hydrochloride (PA). Here, we determined the antiproliferative activity of DDP, either in solution or loaded in liposomes, in the presence of PA, in the bulk solution, or directly embedded in liposomes together with DDP. Our results show that PA potentiates the activity of DDP-liposomes and that this effect is maintained at least in some of the investigated cell types when both drugs were mixed and loaded together into liposomes.

Biotin-Conjugated Multilayer Poly [D,L-lactide-co-glycolide]-Lecithin-Polyethylene Glycol Nanoparticles for Targeted Delivery of Doxorubicin

Multilayer nanoparticle combining the merits of liposome and polymer nanoparticle has been designed for the targeted delivery of doxorubicin (DOX) in cancer treatment. In this study, DOX-PLGA-lecithin-PEG-biotin nanoparticles (DOX-PLPB-NPs) were fabricated and functionalized with biotin for specific tumor targeting. Under the transmission electron microscopy observation, the lipid layer was found to be coated on the polymer core. The physical characteristics of PLPB-NPs were also evaluated. The confocal laser scanning microscopy confirmed the cellular uptake of nanoparticles and targeted delivery PLPB-NPs. The in vitro release experiment demonstrated a pH-depending release of DOX from drug-loaded PLPB-NPs. Cytotoxicity studies in HepG2 cells and in vivo antitumor experiment in tumor-bearing mice both proved DOX-PLPB-NPs showed the best inhibition effect of tumor proliferation. In biodistribution studies, DOX-PLPB-NPs showed a higher DOX concentration than free DOX and DOX-PLGA-lecithin-PEG nanoparticles (DOX-PLP-NPs) in tumor site, especially in 24 h, and the lowest DOX level in normal organs. The results were coincident with the strongest antitumor ability showed among in vivo antitumor experiment. Histopathology analysis demonstrated that DOX-PLPB-NPs exhibited the strongest antitumor ability and lowest cardiotoxicity. In brief, the PLPB-NPs were proved to be an efficient delivery system for tumor-targeting treatment.

Engineering the lipid layer of lipid-PLGA hybrid nanoparticles for enhanced in vitro cellular uptake and improved stability

Lipid-polymer hybrid nanoparticles (NPs), consisting of a polymeric core and a lipid shell, have been intensively examined as delivery systems for cancer drugs, imaging agents, and vaccines. For applications in vaccine particularly, the hybrid NPs need to be able to protect the enclosed antigens during circulation, easily be up-taken by dendritic cells, and possess good stability for prolonged storage. However, the influence of lipid composition on the performance of hybrid NPs has not been well studied. In this study, we demonstrate that higher concentrations of cholesterol in the lipid layer enable slower and more controlled antigen release from lipid-poly(lactide-co-glycolide) acid (lipid-PLGA) NPs in human serum and phosphate buffered saline (PBS). Higher concentrations of cholesterol also promoted in vitro cellular uptake of hybrid NPs, improved the stability of the lipid layer, and protected the integrity of the hybrid structure during long-term storage. However, stabilized hybrid structures of high cholesterol content tended to fuse with each other during storage, resulting in significant size increase and lowered cellular uptake. Additional experiments demonstrated that PEGylation of NPs could effectively minimize fusion-caused size increase after long term storage, leading to improved cellular uptake, although excessive PEGylation will not be beneficial and led to reduced improvement.

STATEMENT OF SIGNIFICANCE

This paper reports the engineering of the lipid layer that encloses a polymeric nanoparticle, which can be used as a carrier for drug and vaccine molecules for targeted delivery. We demonstrated that the concentration of cholesterol is critical for the stability and uptake of the hybrid nanoparticles by dendritic cells, a targeted cell for the delivery of immune effector molecules. However, we found that hybrid nanoparticles with high cholesterol concentration tend to fuse during storage resulting in larger particles with decreased cellular uptake. This problem is subsequently solved by PEGylating the hybrid nanoparticles. With increased research and clinical applications of lipid-polymer hybrid nanoparticles in drug and vaccine delivery, this work will significantly impact the design of the hybrid nanoparticles for minimized molecule release during circulation and increased bioavailability of the target molecules.

Physicochemical properties and biocompatibility of a polymer-paclitaxel conjugate for cancer treatment

Background

Poly(L-γ-glutamylglutamine) paclitaxel (PGG-PTX) conjugate is a non-diblock polymeric drug nanoparticle intended to improve the therapeutic index of paclitaxel. The purpose of the present study was to elucidate further the physicochemical properties of PGG-PTX in order to proceed with its clinical development.

Methods and results

PGG-PTX was designed by integration of a hydrophobic paclitaxel conjugate through an added hydrophilic glutamic acid onto poly(L-glutamic acid). The addition of a flexible glutamic linker between PGA and paclitaxel resulted in spontaneous self-assembly of a PGG-PTX conjugate into nanoparticles. The PGG-PTX conjugate was stable as a lyophilized solid form. An in vitro viability experiment showed that PGG-PTX was effective after a longer incubation period, the same trend as Taxol. In vitro studies using NCI-H460 and B16F0 cancer cells demonstrated significantly high cellular uptake after 30 minutes of incubation. The in vivo biocompatibility of PGG-PTX conjugate was evaluated in the NCI-H460 tumor model, the assessment of tissue seemed to be normal after 21 days of treatment.

Conclusion

These results are encouraging for further development of non-block polymeric paclitaxel nanoparticles for treatment of cancer.

Multifunctional silica nanoparticles for targeted delivery of hydrophobic imaging and therapeutic agents

This article reports the development of a multifunctional silica nanoparticle system for targeted delivery of hydrophobic imaging and therapeutic agents. Normally, silica nanoparticles have been widely used to deliver hydrophilic drugs such as doxorubicin while difficult to carry hydrophobic drugs. A strategy for loading hydrophobic drugs onto silica nanoparticles via covalent attachment was developed in this study as a universal strategy to solve this problem. Docetaxel, one of the most potent therapeutics for cancer treatment is selected as a model hydrophobic drug and quantum dots (QDs) are used as a model imaging agent. Such a multifunctional delivery system possesses high drug loading capacity, controlled drug release behavior and stable drug reservation. A mixed layer of polyethylene glycol conjugated phospholipids is formed on the nanoparticle surface to further enhance the biocompatibility and cell fusion capability of the delivery system. Folic acid as ligand is then conjugated onto the surface layer for targeting. Such a multifunctional system for targeting, imaging and therapy is characterized and evaluated in vitro. Fluorescent confocal microscopy is used to monitor the cellular uptake by specific cancer cells. Cytotoxicity studies are conducted by using MTT assay.

Formulation of Docetaxel by folic acid-conjugated d-α-tocopheryl polyethylene glycol succinate 2000 (Vitamin E TPGS(2k)) micelles for targeted and synergistic chemotherapy

Although high efficacy has been showed, Paclitaxel and Docetaxel cause serious side effects due to the adjuvant used in their clinical formulation Taxol® and Taxotere®. We developed a micelle system with a newly synthesized TPGS(2k) polymer, which shows lower CMC of 0.0219 mg/ml compared with 0.2 mg/ml for traditional micelles with TPGS involved, to achieve sustained and controlled drug delivery with Docetaxel used as a model anti-cancer drug. The TPGS(2k) micelles were further conjugated to folic acid (FA) for targeted drug delivery. The Docetaxel-loaded TPGS(2k) micelles with and without FA conjugation were found of desired size and size distribution, high drug encapsulation efficiency and favorable drug release. In vitro studies using MCF-7 cancer cells demonstrated significantly the higher cellular uptake of the formulated drug for TPGS(2k) micelle formulation than that for Taxotere®. The targeting effects for the FA conjugated TPGS(2k) micelles are also demonstrated. The IC₅₀ value, which is the drug concentration needed for 50% cell viability in the designated time period, is 103.4, 1.280 and 0.1480 μg/ml for MCF-7 cancer cells after 24, 48, and 72 h treatment respectively, which is greatly decreased to be 0.526, 0.251 and 0.233 μg/ml, i.e. a 99.5%, 80.4% decrease and 57.5% increase for the TPGS(2k) micelle formulation, and further decreased to be 0.1780, 0.1520 and 0.1140 μg/ml, i.e. a 99.8%, 88.1% and 23.0% decrease for the folic acid conjugated micelles, respectively. A synergistic effect between TPGS(2k) and Docetaxel is also achieved. The present work represents a new concept in the design of drug delivery systems--the carrier materials of the drug delivery system can also have therapeutic effects, which either modulate the side effects of, or promote a synergistic interaction with the formulated drug.