Yuling Bao

Erythrocyte Membrane-Enveloped Polymeric Nanoparticles as Nanovaccine for Induction of Antitumor Immunity against Melanoma.

Cancer immunotherapy is mainly focused on manipulating patients own immune system to recognize and destroy cancer cells. Vaccine formulations based on nanotechnology have been developed to target delivery antigens to antigen presenting cells (APCs), especially dendritic cells (DCs) for efficiently induction of antigen-specific T cells response. To enhance DC targeting and antigen presenting efficiency, we developed erythrocyte membrane-enveloped poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles for antigenic peptide (hgp10025-33) and toll-like receptor 4 agonist, monophosphoryl lipid (MPLA). A Mannose-inserted membrane structure was constructed to actively target APCs in the lymphatic organ, and redox-sensitive peptide-conjugated PLGA nanoparticles were fabricated which prone to cleave in the intracellular milieu. The nanovaccine demonstrated the retained protein content in erythrocyte and enhanced in vitro cell uptake. An antigen-depot effect was observed in the administration site with promoted retention in draining lymph nodes. Compared with other formulations after intradermal injection, the nanovaccine prolonged tumor-occurring time, inhibited tumor growth, and suppressed tumor metastasis in prophylactic, therapeutic, and metastatic melanoma models, respectively. Additionally, we revealed that nanovaccine effectively enhanced IFN-γ secretion and CD8(+) T cell response. Taken together, these results demonstrated the great potential in applying an erythrocyte membrane-enveloped polymeric nanoplatform for an antigen delivery system in cancer immunotherapy.

d-α-Tocopherol Polyethylene Glycol Succinate-Based Redox-Sensitive Paclitaxel Prodrug for Overcoming Multidrug Resistance in Cancer Cells

To overcome the multidrug resistance (MDR) of P-glycoprotein (P-gp) substrate anticancer drugs, such as paclitaxel (PTX), a novel dual-functional prodrug, D-α-tocopherol polyethylene glycol succinate (TPGS) based PTX prodrug (TPGS-S-S-PTX), was synthesized here to fulfill the synergistic effect of P-gp inhibiting and intracellular redox-sensitive release. The prodrug could self-assemble into stable micelles in physiological environment with a diameter of ∼140 nm, while it disassociated in reductive condition and released PTX and TPGS active derivatives rapidly. High cell cytotoxicity in PTX-resistant human ovarian cell line A2780/T was observed with enhanced PTX accumulation due to the P-gp inhibition by the TPGS moiety. The IC50 of TPGS-S-S-PTX was 55% and 91% more effective than that of Taxol (clinical formulation of PTX) and uncleavable TPGS-C-C-PTX prodrug, respectively. This was found to be related with the increased apoptosis/necrosis and cell arrest in G2/M phase. In vivo evaluation of the TPGS-S-S-PTX prodrug exhibited an extended half-life, increased AUC (area under the concentration-time curve), enhanced tumor distribution and significant tumor growth inhibition with reduced side effects as compared to Taxol and TPGS-C-C-PTX. This prodrug has great potential in improving efficiency in the treatment of MDR tumors.

RGD-decorated redox-responsive D-α-tocopherol polyethylene glycol succinate–poly(lactide) nanoparticles for targeted drug delivery

Developing multifunctional nanoparticles (NPs) to improve therapeutic efficacy is highly desirable in cancer therapy. In an attempt to respond to such a challenge, a novel copolymer, d-α-tocopherol polyethylene glycol succinate-SS-poly(lactide) (TPGS-SS-PLA) with a disulfide linkage between the TPGS and PLA units, was synthesized for paclitaxel (PTX) delivery. PTX-loaded NPs were fabricated using a nanoprecipitation method to form a particle size of ∼130 nm with good in vitro stability, which can be disassociated under intracellular reductive conditions to release PTX rapidly. The detached TPGS can further promote the drug retention and cytotoxicity through its P-glycoprotein inhibiting property. Integrin-specific targeting peptide, cyclic RGD (cRGD), was further conjugated to the surface of the NPs for targeting the drug delivery. The RGD-decorated NPs exhibited enhanced cellular uptake, PTX accumulation and cell cytotoxicity as compared to non-targeted NPs on murine melanoma B16F10 cells, PTX-sensitive human ovarian A2780 cells and PTX-resistant A2780/T cells. In vivo evaluation of the targeted NPs further showed an extended half-life, increased AUC (area under the concentration-time curve), and significant tumor growth inhibition in mouse sarcoma S180- and B16F10-tumor bearing mice, with reduced side effects as compared to Taxol® and non-targeted NPs. These results indicate that the RGD decorated redox-sensitive NPs could deliver chemotherapies specifically inside the cell via receptor-mediated endocytosis with enhanced efficacy, especially in integrin αvβ3/αvβ5-rich tumor cells. Such a targeted nanocarrier against receptor clustering prepared from a non-cytotoxic and biodegradable copolymer might have great potential in cancer treatment.

Lipid-enveloped zinc phosphate hybrid nanoparticles for codelivery of H-2K(b) and H-2D(b)-restricted antigenic peptides and monophosphoryl lipid A to induce antitumor immunity against melanoma.

Nanoimmunotherapy, the application of nanotechnology for sustained and targeted delivery of antigens to dendritic cells (DCs), has attracted much attention in stimulating antigen-specific immune response for antitumor therapy. In order to in situ deliver antigens to DCs for efficient antigen presentation and subsequent induction of strong cytotoxic T lymphocytes (CTL) response, here we developed a multi-peptide (TRP2180-188 and HGP10025-33) and toll-like receptor 4 agonist (monophosphoryl lipid A) codelivery system based on lipid-coated zinc phosphate hybrid nanoparticles (LZnP NPs). This delivery system equips with the chelating property of zinc to realize the high encapsulation efficiency with antigenic peptides and the influence on immune system with adjuvant-like feature. The combination of H-2K(b) and H-2D(b)-restricted peptides could provide multiple epitopes as the target of specific MHC alleles, making tumor more difficult to escape from the surveillance of immune system. The formulated LZnP nano-vaccine with the size of 30nm and outer leaflet lipid exhibited antitumor immunity as the secretion of cytokines in vitro and increased CD8(+) T cell response from IFN-γ ELISPOT analysis ex vivo. The antitumor effects were further evidenced from the prophylactic, therapeutic and metastatic melanoma tumor models compared with free antigens and single peptide-loaded nano-vaccines. These results validate the benefit of LZnP-based vaccine for antitumor immunity and indicate that co-delivery of tumor antigens along with adjuvant may be an optimized strategy for tumor immunotherapy.

Redox/pH dual-sensitive hybrid micelles for targeting delivery and overcoming multidrug resistance of cancer

A redox/pH dual-sensitive graft copolymer, poly(β-amino ester)-g-d-α-tocopherol polyethylene glycol succinate (PBAE-g-TPGS), was synthesized through a Michael-type step polymerization using disulfide linkage-containing TPGS macromonomers. Pluronic F127 (F127) and folate-F127 conjugation were introduced to prepare paclitaxel (PTX)-loaded hybrid micelles to improve their biocompatibility and serum stability and also to achieve targeted delivery. The hybrid micelles exhibited in vitro redox/pH-sensitive PTX release, enhanced cellular uptake through receptor-mediated endocytosis, and strengthened anticancer activities in both the drug-sensitive human breast cancer MCF-7 and drug-resistant MCF-7/ADR cells. P-Glycoprotein inhibition by TPGS and folate-mediated targeted delivery helped overcome multidrug resistance (MDR) and increase the therapeutic efficiency of the drug, leading to good anticancer effects in the MCF-7/ADR xenograft model. Overall, the folate-modified redox/pH-sensitive hybrid micelles provided a three-step approach to enhance anticancer activities via targeted delivery, controlled release, and depressed drug efflux; thus, these micelles may be a powerful weapon against MDR cancers in the future.

Enhanced tumor therapy via drug co-delivery and in situ vascular-promoting strategy

ABSTRACT Conventional tumor starving therapy by reducing its vessel density may be effective at early treatment but potentially contributes to tumor hypoxia, drug resistance and metastasis. A new strategy through enhancing tumor angiogenesis in combination with effective chemotherapeutic drugs, has shown successful tumor growth and spread inhibition. To achieve in situ release of angiogenic and antitumor drugs in tumor, we designed a precise ratiometric polymeric hybrid micelle system for co‐delivering nitric oxide and paclitaxel. The hybrid micelles could accumulate in tumor via the long blood circulation and enhanced permeability and retention (EPR) effect, promote the drug accumulation and penetration in tumor by in situ increased vascular permeability, blood perfusion and vessel density, achieve the synergistic antitumor effect of nitric oxide and paclitaxel through modified tumor microenvironment, overcome multidrug resistance and inhibit metastasis. This study presents a combinational therapy against tumor progression and spread, which shows great potential in cancer therapy of the future.

Nanotechnology based therapeutic modality to boost anti-tumor immunity and collapse tumor defense

Abstract Cancer is still the leading cause of death. While traditional treatments such as surgery, chemotherapy and radiotherapy play dominating roles, recent breakthroughs in cancer immunotherapy indicate that the influence of immune system on cancer development is virtually beyond our expectation. Manipulating the immune system to fight against cancer has been thriving in recent years. Further understanding of tumor anatomy provides opportunities to put a brake on immunosuppression by overcoming tumor intrinsic resistance or modulating tumor microenvironment. Nanotechnology which provides versatile engineered approaches to enhance therapeutic effects may potentially contribute to the development of future cancer treatment modality. In this review, we will focus on the application of nanotechnology both in boosting anti‐tumor immunity and collapsing tumor defense. Graphical abstract Figure. No Caption available.

pH-sensitive micelles with charge-reversible property for tumor growth inhibition and anti-metastasis

Physical properties, such as surface charge, of nanomedicines play a crucial role in their in vivo behaviors, which could eventually determine the tumor inhibition effect. Although drug delivery systems with positive charge are effective for cell internalization, this property is universally applicable to the lack of selectivity of both tumors and normal tissues, resulting in rapid blood clearance and undesired side effects. By employing charge-reversible strategies, the dilemma can be overcome and enhanced cellular uptake, prolonged circulation time and high biocompatibility can be realized. Here, we constructed Vitamin E-based micelles with charge-reversible property for the delivery of the antineoplastic agent paclitaxel. In the slightly acidic tumor microenvironment, the micelles converted from negative to positive charge due to the cleavage of the pH-sensitive bond, leading to enhanced cellular uptake and subsequently enhanced drug release. The micelles demonstrated improved antitumor efficiency both in vitro and in vivo and improved anti-metastasis effect in 4T1 orthotopic tumor model compared with those of clinically formulated Taxol and non-sensitive micelles. Besides, the micelles showed high biocompatibility and reduced side effects. Overall, these findings highlight that the micelles with charge-reversible property have great potential for cancer therapy in clinic.