| Malignant tumor has seriously threaten the health of human.Nowadays,cancer treatments mainly involve surgery,chemotherapy,radiotherapy and immunotherapy.However,all these treatment methods have their own drawbacks which restrict their clinical applications.Surgery cannot cure metastatic tumors.Chemotherapy could lead to some serious toxic and adverse effects due to its lack of tumor selectively.In addition,the long-term chemotherapy can induce drug resistance,thus leading to reduced treatment efficacy.Recently,immunotherapy has attracted much attention due to its high anticancer efficacy,but it is not applicable for all patients.Thus,it is urgent to develop safe and effective therapy strategy for breast cancer treatment.Recently,photothermal therapy(PTT),a noninvasive means to cancer treatment,has attracted extensive attention.PTT uses photothermal agent to convert the energy of near infrared(NIR)light to heat and has some advantages,such as good temporal and spatial control,high selectivity for tumor tissue,and relatively low toxicity to normal tissues.However,PTT alone cannot entirely kill cancer cells due to its uneven heat dispersion within the tumor,the survived cancer cells could lead to local recurrence and distance metastasis.Considering these facts,combining chemotheraly and PTT is an optimal strategy for mammary cancer treatment.Hyperthermia can kill cancer cells and further promote cancer cells to be sensitive to chemotherapy agents,thus achieving better effect.Cancer immunotherapy has become the fourth-biggest treatment method which aroused extensive research in wordwide.It is considered to be the only treatment that may completely cure cancer.DCs therapeutic tumor vaccine has been developed fast.One stragety is to intergrate antigens and adjuvants into vaccine carriers which are decorated with cell surface receptor ligands such as mannose or chemokines for targeting DCs in vivo.Another is to load antigens and adjuvants into DCs in vitro,and then inject the DCs return to patient's body to induce the protective immune response.The ultimate goal of both methods is to activate antigen-specific CD4+ and CD8+ T cells,maximizing the antitumor effects.The DC vaccine is highly safe and can effectively stimulate antitumor immune responses without causing serious side effects.As a kind of excellent nano delivery system,polymeric nanoparticles have great great biocompatibility,biodegradability,flexible design which make it play an important role in cancer therapy.Amphiphilic block polymers can self-assemble into polymeric micelles and polymer vesicles in aqueous phase.We obtained polymeric micelles and polymer vesicles by adjusting the mass ratio of the hydrophilic block PEG and the hydrophobic block PCL,respectively,and explored its application in cancer chemotherapy-photothermal therapy and immunotherapy.The details are as follows:1.Construction of folate-targeted reduction-sensitive double drug-loaded polymer micelles and its application in cancer chemo-photothermal combination therapyAmphiphilic triblock copolymers(PCL-ss-PEG-ss-PCL,PCEP)with reduction-sensitivity,good biocompatibility and biodegradability are used as drug delivery system.Then,chemotherapy drugs doxorubicin(DOX)and photosensitizer indocyanine green(ICG)are used as model hydrophobic drug.Folate(FA)receptor-targeted reductive-responsive polymeric micelles were successfully synthesized using thin film hydration and ultrasonic methods to co-encapsulate DOX and ICG(FA-DINPs)for chemo-and photothermal combination therapy.We characterized the structure of the polymer micelles and carried out the in vitro cell experiments and in vivo animal distribution experiments to evaluate their passive targeting,active targeting capabilities and chemo-photothermal effect.Our studies indicated that folate-targeted reduction-sensitive double drug-loaded polymer micelles prepared by thin film hydration and ultrasonic methods have uniform particle size distribution and high drug loading and entrapment efficacy,particle size stability,reduction sensitivity and good light-to-heat conversion efficiency.The in vitro drug release study indicated that DOX release from FA-DINPs can be controlled by both reduction substance(GSH)and laser irradiation.Cellular uptake study indicated that FA-targeted co-delivery polymer micelles had higher internalization efficiency in FA receptor-overexpressing EMT-6 cells than non-targeted co-delivery polymeric micelles.And the irradiation accelerated the uptake of polymeric micelles by EMT-6 cells.In vitro cytotoxicity study showed that FA-DINPs effectively lower cytotoxicity than Free DOX but had higher cytotoxic effect than DINPs.Combined with laser irradiation,we found that the chemotherapy combined with photothermal therapy exhibited the greastest cytotoxicity.In vivo imaging study showed that FA-DINPs can effectively accumulate in tumors,demonstrating strong targeting property via FA targeting.Therefore,the folate-targeted and reduction-sensitive polymeric micelles are promising delivery system that can simultaneously deliver chemotherapeutic agents and photothermal agents to achieve tumor targeting and synergistic treatment.2.Immune effects of mannose-modified cationic hybrid polymer vesicles loaded with antigens and dual immunostimulants.In this study,polycaprolactone-polyethylene glycol-polycaprolactone(PCL-PEG-PCL,PCEP)amphiphilic triblock copolymer with good biocompatibility and biodegradability was used to formulate the vaccine delivery system.Modal antigen OVA,immunopotentiators imiquimod(IMQ)and monophosphatidyl lipid A(MPLA),and a functional group(mannose)which can target dendritic cells are used to prepare mannose-modified,internal and external co-loading antigens and dual immunostimulatory co-encapsulated polymersomes.We characterized the structure of polymersomes and conductedin vitro release,in vitro cytotoxicity,and in vitro uptake of the polymersomes.The ability of MAN-IMO-PS to promote the cell activation and maturation of DCs was evaluated both in vitro and in vivo.Animal experiment was carried out to examine the distribution of MAN-IMO-PS in vivo,lymphatic reflux capacity and anti-tumor effects in a prophylactic animal model.The TEM results showed that MAN-IMO-PS has a typical bilayer membrane structure with sustained release ability under normal physiological conditions.MAN-IMO-PS has a higher cellular uptake capacity than IMO-PS,and the cytotoxicity results indicate that MAN-IMO-PS has good biocompatibility.MAN-IMO-PS showed antigen-presenting cell targeting capability,increased expression of CD86 and CD40 on the surface of DCs,and up-regulated the corresponding cytokines such as TNF-? and IFN-?.MAN-IMO-PS showed stronger lymphocyte activation,higher immune responses of effector T cells,more potent CD 8+ T and CD4+ T cell responses,and memory T cell immune responses in vivo.Preventive animal model results showed that the MAN-IMO-PS group was able to delay the appearance of tumors and have a better effect in inhibiting tumor growth.Therefore,polymersomes with mannose-modified internal and external co-loading antigens and co-delivered with immunostimulants have wide application prospects in antitumor immunotherapy. |
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