High transfection efficiency and low cytotoxicity are the two key factors to be considered in the design of gene carriers. Herein, a novel and versatile gene carrier (PLL-RT) was prepared by introducing "molecular string" RT (i.e., p-toluylsulfonyl arginine) onto the polylysine backbone. The introduction of RT string contributed to the formation of multiple interactions between the polycationic gene carriers and cell membrane or DNA, as well as adopting α-helix conformation, all of which would be beneficial to enhance the gene transfection. In addition, RT string grafted onto other polycations such as hyperbranced PEI25k and dendrimer PAMAM could also acquire improved transfection efficiency and low cytotoxicity. Moreover, PLL-RT presented significant tumor inhibition effect in vivo. This work provided an effective strategy for constructing novel gene carriers with high transfection and low cytotoxicity.

Immunotherapy holds great promise for patients undergoing tumor treatment. However, the clinical effect of immunotherapy is limited because of tumor immunogenicity and its immunosuppressive microenvironment. Herein, the metal–organic framework (MIL-100) loaded with chemotherapeutic agent mitoxantrone (MTO) was combined with photothermal-chemotherapy for enhancing immunogenic cell death. MIL-100 loaded with MTO and hyaluronic acid as nanoparticles (MMH NPs) yielded an NP with two therapeutic properties (photothermal and chemotherapy) with dual imaging modes (photoacoustic and thermal). When MMH NPs were coinjected with an anti-OX40 antibody in colorectal cancer, the highest antitumor efficacy and a robust immune effect were achieved. This work provides a novel combined therapeutic strategy, which will hold great promise in future tumor therapy.

Immunotherapy has become a powerful cancer treatment, but only a small fraction of patients have achieved durable benefits due to the immune escape mechanism. In this study, epigenetic regulation is combined with gene therapy-mediated immune checkpoint blockade to relieve this immune escape mechanism. PPD (i.e., mPEG-b-PLG/PEI-RT3/DNA) is developed to mediate plasmid-encoding shPD-L1 delivery by introducing multiple interactions (i.e., electrostatic, hydrogen bonding, and hydrophobic interactions) and polyproline II (PPII)-helix conformation, which downregulates PD-L1 expression on tumour cells to relieve the immunosuppression of T cells. Zebularine (abbreviated as Zeb), a DNA methyltransferase inhibitor (DNMTi), is used for the epigenetic regulation of the tumour immune microenvironment, thus inducing DC maturation and MHC I molecule expression to enhance antigen presentation. PPD plus Zeb combination therapy initiates a systemic anti-tumour immune response and effectively prevents tumour relapse and metastasis by generating durable immune memory. This strategy provides a scheme for tumour treatment and the inhibition of relapse and metastasis.

Tumor nanovaccines have potential applications in the prevention and treatment of malignant tumors. However, it remains a longstanding challenge in exploiting efficient nanocarriers for inducing potent specifically cellular immune responses. Toward this objective, we herein explore an intensive tumor immunotherapeutic strategy by combining mannosylated nanovaccines and gene regulated PD-L1 blockade for immune stimulation and killing activity. Here, we fabricate a mannose modified PLL-RT (Man-PLL-RT) mediated nanovaccines with dendritic cells (DCs) targeting capacity. Man-PLL-RT is capable of co-encapsulating with antigen (ovalbumin, OVA) and adjuvant (unmethylated cytosine-phosphate-guanine, CpG) by electrostatic interaction. This positively charged Man-PLL-RT/OVA/CpG nanovaccines can facilitate the endocytosis, maturation and cross presentation in DCs. However, the nanovaccines arouse limited inhibition of tumor growth, which is mainly due to the immunosuppressed microenvironment of tumors. Combining tumor nanovaccines with gene regulated PD-L1 blockade leads to an obvious tumor remission in B16F10 melanoma bearing mice. The collaborative strategy provides essential insights to boost the benefits of tumor vaccines by regulating the checkpoint blockade with gene therapy.

Radiotherapy (RT), as one of the main methods in the clinical treatment of various malignant tumors, would induce systemic immunotherapeutic effects by triggering immunogenic cell death (ICD) of cancer cells. However, the antitumor immune responses produced by RT-induced ICD alone usually are not robust enough to eliminate distant tumors and thus ineffective against cancer metastases. Herein, a biomimetic mineralization method for facile synthesis of MnO 2 nanoparticles with high antiprogrammed death ligand 1 (αPDL1) encapsulation efficiency (αPDL1@MnO 2 ) is proposed to reinforce RT-induced systemic antitumor immune responses. This therapeutic nanoplatformsmediated RT can significantly improve the killing of tumor cells and effectively evoke ICD by overcoming hypoxia-induced radioresistance and reprogramming the immunosuppressive tumor microenvironment (TME). Furthermore, the released Mn 2+ ions from αPDL1@MnO 2 under acidic tumor pH can activate the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway and facilitate the dendritic cells (DCs) maturation. Meanwhile, αPDL1 released from αPDL1@MnO 2 nanoparticles would further promote the intratumoral infiltration of cytotoxic T lymphocytes (CTLs) and trigger systemic antitumor responses, resulting in a strong abscopal effect to effectively inhibit tumor metastases. Overall, the biomineralized MnO 2 -based nanoplatforms offer a simple strategy for TME modulation and immune activation, which are promising for enhanced RT immunotherapy.

A zinc ion coordination-contained polycationic gene delivery system.

Constructing an efficient in vivo gene delivery system has always been extremely challenging. Herein, a highly efficient H2O2-responsive in vivo polycationic gene delivery system is developed for the first time. The efficient vector PLL-RT (i.e., polylysine grafted with p-tosyl-l-arginine) is used to mediate plasmid DNA (pDNA) delivery, and H2O2-responsive thioketal dipropanedioic acid-modified dextran (TDPAD) is used as a shielding system for effectively coating vector/pDNA polyplexes. The constructed gene delivery system exhibits a prolonged circulatory half-life in vivo and accelerates the accumulation of vector/DNA polyplexes in tumor tissue by the enhanced permeability and retention (EPR) effect. Moreover, this gene delivery system exhibits highly efficient and synergistic antitumor effects through a strategy of killing three birds with one stone. First, upon the arrival of TDPAD/PLL-RT/pDNA [abbreviated as T­(PD)] at the tumor site by the EPR effect, TDPAD reacts with excess H2O2 in tumor tissue, contributing to the detachment of TDPAD, and PLL-RT then mediates the enhanced endocytosis of pDNA encoding shVEGF and significantly downregulates the expression of vascular endothelial growth factor (VEGF) in tumor tissue, exhibiting an outstanding antitumor effect. Second, the H2O2 consumption by TDPAD significantly decreases the H2O2 level in tumor tissue, which synergistically suppresses tumor growth. Third, small-molecule product mercaptopropionic acid, generated by the reaction of TDPAD with H2O2, can induce cancer cell apoptosis and exert pronounced antitumor efficacy. This polycationic gene delivery system shows negligible toxicity in vitro and in vivo. This strategy provides an ideal platform for constructing an efficient in vivo gene delivery system and has bright prospects for cancer therapy.

Oral administration of protein drugs has always been challenging owing to various intestinal barriers. Herein, we developed an efficient oral protein delivery strategy by using in situ polymerization of zwitterions to encapsulate proteins, which were then loaded into enteric coated capsules for oral feeding. After oral administration of such capsules, the enteric coating would be degraded once the capsule enters the intestine, releasing polyzwitterion/protein nanocomplexes. With the help of polyzwitterion modification, such nanocomplexes were able to pass through the mucus and cellular barriers, likely by the proton-assisted amino acid transporter 1 (PAT1) pathway. Such a polyzwitterion-based protein encapsulation strategy could allow for effective oral delivery of different proteins, including bovine serum albumin (BSA), insulin, and antibodies. Using this strategy, the oral bioavailabilities of insulin and immunoglobin G (IgG) were measured to be as high as 16.9% and 12.5%, respectively. Notably, oral feeding of polyzwitterion/insulin capsules could effectively lower the blood glucose level of diabetic animals (mice, rats, and pigs). Moreover, polyzwitterion/antiprogramed death-1 (αPD-1) capsules were able to induce efficient antitumor immune responses, showing significant tumor inhibition effects toward B16F10- and 4T1-tumor bearing mouse models after oral administration. No significant toxic effect was observed for such oral protein formulations in the treated animals. Our work presents a strategy for the efficient oral delivery of protein drugs, including those with large molecular weights (e.g., antibodies) that can hardly be orally delivered using existing technologies.