Tumor microenvironment and redox dual stimuli-responsive polymeric nanoparticles for the effective cisplatin-based cancer chemotherapy.

The serious side effects of cisplatin hindered its clinical application and the nanotechnology might be the potential strategy to address the limitation. However, rapid clearance in the blood circulation and ineffective controlled drug release from nanocarriers hamper the therapeutic efficacy of the nano-delivery system. We constructed a tumor microenvironment and redox dual stimuli-responsive nano-delivery system PEG-c-(BPEI-SS-Pt) by cross-linking the disulfide-containing polymeric conjugate BPEI-SS-Pt with the dialdehyde group-modified PEG2000via Schiff base. After optimized the cross-linking time, 72 h was selected to get the nano-delivery system.1H NMR and drug release assays showed that under the acidic tumor microenvironment (pH 6.5-6.8), the Schiff base can be broken and detached the PEG cross-linked outer shells, displaying the capability to release the drugs with a sequential pH- and redox-responsive manner. Moreover, PEG-c-(BPEI-SS-Pt) showed more effective anti-tumor therapeutic efficacyin vivowith no significant side effects when compared with the drug of cisplatin used in the clinic. This strategy highlights a promising platform with the dual stimuli-responsive profile to achieve better therapeutic efficacy and minor side effects for platinum-based chemotherapy.

Polyethylenimine-based nanovector grafted with mannitol moieties to achieve effective gene delivery and transfection.

Polyethylenimine (PEI), a kind of cationic non-viral gene delivery vector, is capable of stable and efficient transgene expression for gene delivery. However, low transfection efficiency in vivo along with high toxicity limited the further application of gene therapy in the clinic. To enhance gene transfection performance and reduce cytotoxicity of polyethylenimine, branched polyethylenimine-derived cationic polymers BPEI25 k-man-S/L/M/H with different grafting degree with mannitol moieties were prepared and the transfection efficiency was evaluated. Among them, BPEI25 k-man-L showed the best transfection efficiency, lower toxicity, and significantly enhanced long-term systemic transgene expression for 96 h in vivo even at a single-dose administration. The results of cellular uptake mechanism and western-blot experiments revealed that the mannitol modification of BPEI25 k induced and up-regulated the phosphorylation of caveolin-1 and thus enhanced the caveolae-mediated cellular uptake. This class of gene delivery system highlights a paradigmatic approach for the development of novel and safe non-viral vectors for gene therapy.

Mitochondria and Nucleus Dual Delivery System To Overcome DOX Resistance.

Doxorubicin (DOX) is a broad-spectrum chemotherapy drug to treat tumors. However, severe side effects and development of DOX resistance hinder its clinical application. In order to overcome DOX resistance, DOX/TPP-DOX@Pasp-hyd-PEG-FA micelles were prepared by using newly synthesized comb-like amphiphilic material Pasp-hyd-PEG-FA. Drug released in vitro from micelles showed a pH-dependent manner. DOX/TPP-DOX@Pasp-hyd-PEG-FA induced more apoptosis in KB cell and MCF-7/ADR cell than DOX@Pasp-hyd-PEG-FA. Confocal laser scanning microscopy experiment indicated that DOX/TPP-DOX@Pasp-hyd-PEG-FA delivered TPP-DOX and DOX to the nucleus and mitochondria of the tumor cell simultaneously. Thus, DOX/TPP-DOX@Pasp-hyd-PEG-FA could significantly damage the mitochondrial membrane potential. DOX/TPP-DOX@Pasp-hyd-PEG-FA markedly shrinked the tumor volume in tumor-bearing nude mice grafted with MCF-7/ADR cell as compared with the same dose of free DOX. DOX was mainly accumulated in tumor tissue after DOX/TPP-DOX@Pasp-hyd-PEG-FA was injected to tumor-bearing nude mice by tail vein. After free DOX was injected to tumor-bearing nude mice by tail vein, DOX widely distributed through the whole body. Therefore, mitochondria and nucleus dual delivery system has potential in overcoming DOX resistance.

Design and application of cationic amphiphilic ß-cyclodextrin derivatives as gene delivery vectors.

The nano self-assembly profiles of amphiphilic gene delivery vectors could improve the density of local cationic head groups to promote their DNA condensation capability and enhance the interaction between cell membrane and hydrophobic tails, thus increasing cellular uptake and gene transfection. In this paper, two series of cationic amphiphilic ß-cyclodextrin (ß-CD) derivatives were designed and synthesized by using 6-mono-OTs-ß-CD (1) as the precursor to construct amphiphilic gene vectors with different building blocks in a selective and controlled manner. The effect of different type and degree of cationic head groups on transfection and the endocytic mechanism of ß-CD derivatives/DNA nanocomplexes were also investigated. The results demonstrated that the designed ß-cyclodextrin derivatives were able to compact DNA to form stable nanocomplexes and exhibited low cytotoxicity. Among them, PEI-1 with PEI head group showed enhanced transfection activity, significantly higher than commercially available agent PEI25000 especially in the presence of serum, showing potential application prospects in clinical trials. Moreover, the endocytic uptake mechanism involved in the gene transfection of PEI-1 was mainly through caveolae-mediated endocytosis, which could avoid the lysosomal degradation of loaded gene, and had great importance for improving gene transfection activity.

pH-Triggered Surface Charge Reversed Nanoparticle with Active Targeting To Enhance the Antitumor Activity of Doxorubicin.

PLGA nanoparticles are widely used in tumor targeting drug delivery systems. However, the naked PLGA nanoparticles (NNPs) not only have low drug loading but also can be rapidly removed from blood circulation by the immune system. The aim of this study was to prepare pH-triggered surface charge reversed lipid hybrid PLGA nanoparticles (LNPs) to enhance drug loading and drug delivery efficiency. CHO-Arg-His-OMe and FA-PEG-DSPE were synthesized to modify PLGA nanoparticles to prepare LNPs. The drug loading and encapsulation rate of LNPs were greatly improved as compared with NNPs. In pH 7.4 medium, doxorubicin (DOX)-loaded LNPs showed negative charge and released DOX slowly. In pH 5.0 medium, DOX-loaded LNPs exhibited positive charge and released DOX quickly. DOX-loaded LNPs delivered more DOX to the nucleus of KB cells and MBA-MD-231/ADR cells than did free DOX. In addition, DOX-loaded LNPs significantly inhibited the proliferation of KB cells and MBA-MD-231/ADR cells. Compared with free DOX, the same dose of the DOX-loaded LNPs delivered more DOX to tumor tissue. Thus, DOX-loaded LNPs significantly inhibited the growth of tumor in tumor-bearing nude mice and obviously reduced the systemic toxicity of DOX. In conclusion, pH-triggered surface charge reversed DOX-loaded LNPs significantly enhanced the antitumor activity of DOX in vitro and in vivo. DOX-loaded LNPs had great potential in tumor targeted chemotherapy.

Cholesterol derived cationic lipids as potential non-viral gene delivery vectors and their serum compatibility.

Cholesterol derivatives M1-M6 as synthetic cationic lipids were designed and the biological evaluation of the cationic liposomes based on them as non-viral gene delivery vectors were described. Plasmid pEGFP-N1, used as model gene, was transferred into 293T cells by cationic liposomes formed with M1-M6 and transfection efficiency and GFP expression were tested. Cationic liposomes prepared with cationic lipids M1-M6 exhibited good transfection activity, and the transfection activity was parallel (M2 and M4) or superior (M1 and M6) to that of DC-Chol derived from the same backbone. Among them, the transfection efficiency of cationic lipid M6 was parallel to that of the commercially available Lipofectamine2000. The optimal formulation of M1 and M6 were found to be at a mol ratio of 1:0.5 for cationic lipid/DOPE, and at a N/P charge mol ratio of 3:1 for liposome/DNA. Under optimized conditions, the efficiency of M1 and M6 is greater than that of all the tested commercial liposomes DC-Chol and Lipofectamine2000, even in the presence of serum. The results indicated that M1 and M6 exhibited low cytotoxicity, good serum compatibility and efficient transfection performance, having the potential of being excellent non-viral vectors for gene delivery.

Novel cholesterol-based cationic lipids as transfecting agents of DNA for efficient gene delivery.

The design, synthesis and biological evaluation of the cationic lipid gene delivery vectors based on cholesterol and natural amino acids lysine or histidine are described. Cationic liposomes composed of the newly synthesized cationic lipids 1a or 1b and neutral lipid DOPE (1,2-dioleoyl-L-α-glycero-3-phosphatidyl-ethanolamine) exhibited good transfection efficiency. pEGFP-N1 plasmid DNA was transferred into 293T cells by cationic liposomes formed from cationic lipids 1a and 1b, and the transfection activity of the cationic lipids was superior (1a) or parallel (1b) to that of the commercially available 3ß-[N-(N',N'-dimethylaminoethyl)-carbamoyl] cholesterol (DC-Chol) derived from the same cholesterol backbone with different head groups. Combined with the results of agarose gel electrophoresis, transfection experiments with various molar ratios of the cationic lipids and DOPE and N/P (+/-) molar charge ratios, a more effective formulation was formed, which could lead to relatively high transfection efficiency. Cationic lipid 1a represents a potential agent for the liposome used in gene delivery due to low cytotoxicity and impressive gene transfection activity.

Polymer-Initiating Caveolae-Mediated Endocytosis and GSH-Responsive MiR-34a Gene Delivery System for Enhanced Orthotopic Triple Negative Breast Cancer Therapy.

Gene therapy based on miRNAs has broad application prospects in the treatment of tumors. However, due to degradation and ineffective release during intracellular transport, current gene delivery vectors used for miRNAs limited their actual transfection efficiency. This study develops a novel nonviral vector PEI-SPDP-Man (PSM) that can simultaneously target cellular uptake pathways and intracellular responsive release for miR-34a. PSM is synthesized by connected mannitol (Man) to branched polyethylenimine (PEI) using a disulfide bond. The prepared PSM/miR-34a gene delivery system can induce and enter to tumor cells through caveolae-mediated endocytosis to reduce the degradation of miR-34a in lysosomes. The disulfide bond is sensed at high concentration of glutathione (GSH) in the tumor cells and miR-34a is released, thereby reducing the expression of Bcl-2 and CD44 to suppress the proliferation and invasion of tumor cells. In vitro and in vivo experiments show that through the targeted cellular uptake and the efficient release of miR-34a, an effective antitumor and antimetastasis profiles for the treatment of orthotopic triple negative breast cancer (TNBC) are achieved. This strategy of controlling intracellular transport pathways by targeting cellular uptake pathways in the gene therapy is an approach that could be developed for highly effective cancer therapy.

Mitochondria and nucleus delivery of active form of 10-hydroxycamptothecin with dual shell to precisely treat colorectal cancer.

AIM: The objective of this study was to deliver a ring-closed form of 10-hydroxycamptothecin (HCPT) to the mitochondria and nucleus to treat colorectal cancer. MATERIALS & METHODS: HCPT-loaded nanoparticle HCPT@PLGA-PEG2k-triphenylphosphonium/PLGA-hyd-PEG4k-folic acid (PT/PHF) and HCPT@PT/PLGA-SS-PEG4k-folic acid (PSF) were prepared by using emulsion-solvent evaporation method. RESULTS: In vitro experimental results indicated HCPT@PT/PHF and HCPT@PT/PSF maintained a large amount of HCPT in active form, and delivered more HCPT to the nucleus and mitochondria of the tumor cell, which resulted in the enhancement of cytotoxicity of HCPT. In vivo experimental results indicated that HCPT@PT/PHF and HCPT@PT/PSF delivered more ring-closed form of HCPT to tumor tissue, which led to strong antitumor activity. CONCLUSION: HCPT@PT/PHF and HCPT@PT/PSF could enhance therapeutic efficacy of HCPT to colorectal cancer.