A hierarchical assembly strategy to engineer dextran-enveloped polyurethane nanopolyplexes for robust ovarian cancer gene therapy

Cell membrane breakage and triggering T cell infiltration are involved in human telomerase reverse transcriptase (hTERT) promoter-driven novel peptide KK-64 for liver cancer gene therapy

Liver cancer is an aggressive malignancy with exhibits both high mortality and morbidity. The current treatment options are associated with several limitations, novel specific anti-cancer drugs are urgently needed to improve liver cancer treatment. In this study, a new peptide KK-64 was designed, and it showed strong cytotoxicity against liver cancer cells. To obtain the tumor targeting property, a plasmid that contains KK-64 DNA fragment and driven by human telomerase reverse transcriptase (hTERT) promoter was constructed. pcTERT-kk-64 plasmid was found to specifically inhibit the viability of liver cancer cells HepG2, induce substantial apoptosis as well as damage to the cell membranes, but had minimal effects toward normal liver HL-7702 cells. Furthermore, pcTERT-kk-64 plasmids was also noted to significantly attenuate migration and invasion of HepG2 cells. The anti-tumor effect of pcTERT-kk-64 plasmid was also observed in H22 cell-bearing mice, and it appeared to cause significant tumor regression, trigger tumor cell apoptosis, and infiltrate cytotoxicity T cells to the tumor tissues after plasmids injection. Thus, pcTERT-kk-64 plasmids showed both strong cytotoxicity and tumor selectivity in vitro and in tumor-bearing mice in liver cancer models.

Biopolymer-based Carriers for DNA Vaccine Design

Over the last 30 years, genetically engineered DNA has been tested as novel vaccination strategy against various diseases, including human immunodeficiency virus (HIV), hepatitis B, several parasites, and cancers. However, the clinical breakthrough of the technique is confined by the low transfection efficacy and immunogenicity of the employed vaccines. Therefore, carrier materials were designed to prevent the rapid degradation and systemic clearance of DNA in the body. In this context, biopolymers are a particularly promising DNA vaccine carrier platform due to their beneficial biochemical and physical characteristics, including biocompatibility, stability, and low toxicity. This article reviews the applications, fabrication, and modification of biopolymers as carrier medium for genetic vaccines.

Dual-responsive click-crosslinked micelles designed for enhanced chemotherapy for solid tumors

The design of multiple stimuli-responsive, stable polymeric drug carriers is key for efficient drug release against solid tumors. Herein, core-crosslinked micelles were readily prepared from a pair of redox/pH-sensitive clickable copolymers. The two copolymers comprised the same poly(ethylene glycol) (PEG)-poly(ε-benzyloxycarbonyl-l-lysine) (PZLL) block but with either disulfide-linked azadibenzocyclooctyne (DBCO) or azide (AZ) group-tagged branched polyethylenimine (BPEI, 1.8 kDa). The data showed that an equivalent of the two copolymers could self-assemble into nanosized micelles with the crosslinked core via the DBCO-AZ click chemistry. The click-crosslinked micelles showed excellent size stability under multiple dilutions but destabilization in an acidic or reductive environment. Besides, they could load doxorubicin (DOX), an anticancer drug, and mediate slow drug release in a neutral environment but sufficient drug unloading under acidic plus reductive conditions. In vitro, DOX-loaded crosslinked micelles led to higher DOX accumulation in the cellular nucleus in comparison with non-crosslinked micelles from the PEG-PZLL-BPEI copolymer (PP), thus causing more marked cytotoxicity in SKOV-3 cells. In vivo, DOX-loaded crosslinked micelles caused significant growth inhibition of SKOV-3 tumors xenografted in BALB/c nude mice, and showed superior anticancer efficacy to non-crosslinked PP micelles. Chemotherapy with core-crosslinked micelles had no adverse side effects on the health (serum levels and body weight) of the mice. This study highlights the design of clickable block copolymers to easily construct core-crosslinked and multiple stimuli-responsive micelles for enhanced anticancer therapy.

Black phosphorus quantum dots encapsulated in anionic waterborne polyurethane nanoparticles for enhancing stability and reactive oxygen species generation for cancer PDT/PTT therapy

Black phosphorus quantum dots (BPQDs) with excellent biocompatibility, outstanding photothermal and photodynamic efficacies have attracted significant attention in cancer therapy. However, the low environmental stability and poor dispersity of BPQDs limit their practical applications. In the present work, biocompatible anionic waterborne polyurethane (WPU) nanoparticles were synthesized from castor oil to encapsulate the BPQDs. The WPU-BPQDs with a BPQDs loading capacity of about 13.8% (w/w) exhibited significantly improved dispersion and environmental stability without affecting the photothermal efficiency of BPQDs. Intriguingly, it was found that WPU encapsulation led to significant enhancement in the reactive oxygen species (ROS) generation of BPQDs, which indicated the enhanced photodynamic efficacy of the encapsulated BPQDs as compared to the bare BPQDs. The effect of solution pH on the ROS generation efficiency of BPQDs and the pH variation caused by BPQDs degradation was then investigated to explore the possible mechanism. In acidic solution, ROS generation was suppressed, while BPQDs degradation led to the acidification of the solution. Fortunately, after being encapsulated inside the WPU nanoparticles, the degradation rate of BPQDs became slower, while the acidic environment around BPQDs was favorably regulated by WPU nanoparticles having a special electrochemical double layer consisting of interior COO^- and exterior NH(Et₃)⁺, thus endowing the WPU-BPQDs-boosted production of ROS as compared to the bare BPQDs. Considering the undesired acidic tumor environment, this unique pH regulation effect of WPU-BPQDs would be beneficial for in vivo photodynamic efficacy. Both in vitro and in vivo experiments showed that WPU-BPQDs could effectively improve photodynamic therapy (PDT) and maintain outstanding photothermal therapy (PTT) effects. Together with the excellent dispersity, biocompatibility, and easy biodegradability, WPU-BPQDs can be a promising agent for PDT/PTT cancer treatments.

Reactive oxygen species-activatable camptothecin polyprodrug based dextran enhances chemotherapy efficacy by damaging mitochondria

Low loading capacity, poor accumulation rate and weak permeability at tumor sites have been identified as the critical barriers for anti-cancer nanomedicines (ANMs). We herein reported a reactive oxygen species (ROS)-activatable ANM of dextran-b-P(CPTMA-co-OEGMA) (DCPT). It aimed to meet the above challenges for improving the therapeutic efficiency of chemotherapy. In this system, camptothecin (CPT) was selected as a chemotherapy drug and poly(ethylene glycol)methyl ether methacrylate (OEGMA) played the role of a hydrophilic block to enhance the water solubility of polyprodrug micelles. At high ROS levels in the tumor microenvironment, the micelles could be disassembled, and simultaneously, the anti-cancer drug of CPT would be released from the DCPT micelles. The 4T1-tumor growth would be greatly inhibited by these two DCPT polyprodrugs, with outstanding in vivo biosafety. The results of both in vitro and in vivo studies indicated the superior therapeutic effects of DCPT. The rational design of polyprodrug nanomedicines may serve as a promising strategy for the development of tumor microenvironment-responsive ANMs, thus improving chemotherapy efficacy.

Bioreducible crosslinked cationic nanopolyplexes from clickable polyethylenimines enabling robust cancer gene therapy

Bioreducible crosslinked polyplexes from branched polyethylenimine (BPEI, 10 kDa) were successfully constructed through DNA neutralization by disulfide-linked azidated BPEI (PAZ) and subsequent DNA condensation by azadibenzocyclooctyne-modified BPEI (PDB), following their self-crosslinking via azide-azadibenzocyclooctyne click chemistry. Click-crosslinked cationic polyplexes (c-polyplexes) revealed high extracellular colloidal stability against negative heparin and ions while intracellular bioreducible degradability for efficient gene unpacking. In vitro gene transfection in cancer cells indicated that the c-polyplexes produced markedly higher transfection efficiency than non-crosslinked counterparts in the serum. The c-polyplexes also had prolonged circulation kinetics, elevated gene accumulation level in SKOV-3 tumor xenografted in a mouse model and in turn superior transgene expression in the tumor. By small hairpin RNA for VEGF silencing, the c-polyplexes exerted significant tumor growth inhibition following with low systemic toxicity in the mouse. This study highlights the design of clickable polycations to construct crosslinked cationic nanopolyplexes for intravenous gene delivery against cancer.

Bioreducible poly(urethane amine)s for robust nucleic acid transfection in stem cells

The search for cationic polymeric carriers enabling robust gene transfection against stem cells remains a challenge. Herein, linear bioreducible poly(urethane amine)s (denoted as SSPUAs) with repeated disulfide and protonable amino groups were prepared and used as non-viral vectors for in vitro gene transfection of different stem cells. The polyurethane copolymers (denoted as SSBT) with varied molar ratios of 1,4-bis(3-aminopropyl)piperazine (BAP) and tris(2-aminoethyl) amine (TAA) moieties could lead to superb transfection activity against human adipose-derived stem cells (hADSCs) and human bone marrow stem cells (hBMSCs). Data indicated that under optimal transfection conditions, SSBT10 with a BAP/TAA molar ratio of 90/10 caused the transfection of ∼60% of green fluorescence protein-positive (GFP⁺) hADSCs, and SSBT30 with the ratio of 70/30 resulted in the transfection of ∼40% of GFP⁺ hBMSCs. Also, the SSBT30 and polyurethane with BAP residues (denoted as SSBAP) could mediate efficient gene transfer into bone marrow stem cells of experimental animals such as SD rats, beagle dogs and rhesus monkeys, with ∼40-70% of GFP⁺ cells. Additionally, the SSBAP elicited robust transfection ability (∼60% of GFP⁺ cells) against E14 mouse embryonic stem cells without compromising the expression of multipotent stemness-related markers of the cells. Importantly, the transfection efficiencies of these SSPUAs were higher as compared to those yielded by 25 kDa branched polyethylenimine and Lipofectamine 2000 reagents as positive controls. The SSBT30 was further practical to deliver siRNAs into hADSCs for BCL2L2 or TRIB2 gene silencing, causing superior gene silencing efficacy to Lipofectamine 2000. Besides their high gene transfection or silencing efficacy, these SSPUAs revealed low cytotoxicity against stem cells. This study highlights the SSPUA system as a distinct platform for robust nucleic acid delivery into stem cells.