ABSTRACT
The combination of chemotherapeutic agents with immune stimulating agents for treating degenerative diseases, called chemoimmunotherapy, has emerged as a promising cancer treatment modality. Despite the tremendous potential, chemoimmunotherapy by the combination of drugs and immune stimulators often suffers because of the lack of controlled delivery nanostructures in the microenvironment. To this end, we show that by using pH-responsive smart nanocubes (NCs), cancer cells and tumor-associated immune cells can be precisely targeted with a chemotherapeutic agent (doxorubicin, DOX) and immune stimulating agent (plasmid ovalbumin, pOVA) for enhanced chemoimmunotherapy. The pH-responsive smart NCs protect payloads from nuclease degradation and avoid renal clearance and undergo supersensitive structural change at the extracellular tumor regions that mediate efficient release. Concurrent release of pOVA vaccines encoding tumor-specific antigen laden with polyplexes were loaded on tumor-associated immune cells and produce antigen-specific humoral immune response, whereas DOX enables effective infiltration into the cancer cells and is involved in the eradication of tumor tissues. The amount of anti-OVA IgG1 antibody produced by the intravenous administration of NC formulation was similar to that of free OVA formulation. Importantly, the combined delivery of pDNA and DOX using NCs showed significantly enhanced antitumor efficacy in B16/OVA melanoma tumor xenografts, which remarkably outperforms the monotherapy counterparts. These results suggest that pH-responsive smart NCs laden with pDNA and DOX provide a promising nanostructure for chemoimmunotherapy that simultaneously involves cancer cell killing and stimulates antigen-specific immune response to prevent cancer recurrence.
Subject(s)
Drug Delivery Systems , Melanoma, Experimental/therapy , Nanoparticles/administration & dosage , Vaccines, DNA/administration & dosage , Animals , Cancer Vaccines/administration & dosage , Cancer Vaccines/chemistry , Cancer Vaccines/genetics , Cancer Vaccines/immunology , Doxorubicin/administration & dosage , Doxorubicin/chemistry , Drug Carriers/administration & dosage , Drug Carriers/chemistry , Drug Liberation , Humans , Hydrogen-Ion Concentration , Immunotherapy/methods , Melanoma, Experimental/genetics , Melanoma, Experimental/immunology , Mice , Nanoparticles/chemistry , Ovalbumin/administration & dosage , Ovalbumin/chemistry , Vaccines, DNA/genetics , Vaccines, DNA/immunology , Xenograft Model Antitumor AssaysABSTRACT
In this study, we hypothesized that the delivery of molecules that regulate the microenvironment after a cerebral infarction can influence regeneration potential after a stroke. Stromal cell-derived factor-1α (SDF-1α) is a chemoattractant molecule that plays a pivotal role in recruiting endothelial progenitor cells (EPCs) to the infarct region after stroke. Increased SDF-1α expression leads to increased EPCs homing at the infarct region and induces neurogenesis, angiogenesis, neuroprotection, and stem cell homing. Thus, we evaluated the effects of targeted delivery of SDF-1α using a pH-sensitive polymer poly (urethane amino sulfamethazine) (PUASM), a synthetic macromolecule with potential for targeted drug delivery in acidic conditions, to enhance therapeutic neurogenesis and angiogenesis in a rat model of permanent middle cerebral artery occlusion. A dual ionic pH-sensitive copolymer PUASM-based random copolymer was designed and synthesized for the controlled release of SDF-1α in stroke. Owing to the unique characteristics of PUASM, it exhibited a dual ionic pH-sensitive property in an aqueous solution. At pH 8.5, the copolymer exhibited a negative charge and was water soluble. Interestingly, when the pH decreased to 7.4, PUASM could form a micelle and encapsulate protein effectively via the ionic interaction between a negatively charged polymer and a positively charged protein. At pH 5.5, the ionization of tertiary amines led to the disassembly of the micellar structure and released the protein rapidly. Then, we investigated the effect of systemic administration of SDF-1α-loaded pH-sensitive polymeric micelles in a stroke induced rat model. An enzyme-linked immunosorbent assay showed increased expression of SDF-1α in the ischemic region, indicating that the pH-sensitive micelles effectively delivered SDF-1α into the ischemic region. In order to observe the biodistribution of SDF-1α in the ischemic region, it was labeled with the near-infrared dye, Cy5.5. Optical imaging showed that the Cy5.5 signal increased in the infarct region 24 h after administration. Immunohistochemistry data showed that targeted delivery of SDF-1α enhanced neurogenesis and angiogenesis, but did not influence cell survival or inflammation. These observations suggest that SDF-1α-loaded pH-sensitive polymeric micelles can be used as pH-triggered targeting agents and can effectively modify the microenvironment to increase innate neurorestorative processes.
