Development of novel tracers for sentinel node identification in cervical cancer.

Indocyanine green (ICG) with near-infrared (NIR) fluorescence imaging is used for lymphatic mapping. However, binding of ICG to blood proteins like serum albumin can shorten its retention time in sentinel lymph nodes (SLNs). Here, we investigated the efficacy and safety of a new fluorescence tracer comprising phytate and liposome (LP)-encapsulated ICG. Coadministration of phytate with LP containing phosphatidic acid promotes chelation mediated by Ca2+ in bodily fluids to enhance SLN retention. Uniformly sized LPs (100 nm) encapsulating ICG under conditions that minimized fluorescence self-quenching during storage were produced. We analyzed the behavior of the new tracer (ICG-phytate-LP) and control tracers (ICG and ICG-LP) in the lymphatic flow of mice in terms of lymph node retention time. We also tested lymphatic flow and safety in pigs that have a more human-like lymphatic system. LPs encapsulating stabilized ICG were successfully prepared. Mixing LP with phytate in the presence of Ca2+ increased both the particle size and negative surface charge. In mice, ICG-phytate-LP had the best lymph node retention, with a fluorescence intensity ratio that increased over 6 h and then decreased slowly over the next 24 h. In pigs, administration of ICG and ICG-phytate-LP resulted in no death or weight loss. There were no obvious differences between blood test results for the ICG and ICG-phytate-LP groups, and the overall safety was good. ICG-phytate-LP may be a useful new tracer for gynecological cancers that require time for lymph node identification due to a retroperitoneal approach.

A human cell orthogonal enzyme ß-D-galacturonidase for sensitive detection of antigen proteins.

Enzymes are used to amplify signals for detection of antigen proteins in biological samples. However, the enzymes conventionally used for this purpose have limitations, such as the presence of the same (i.e., endogenous) activity in human cells and difficulty in simultaneous use of multiple enzymes because of differences in their required reaction conditions. In this report, we identify an enzyme that can overcome these problems: ß-D-galacturonidase (GalUAase) from Eisenbergiella tayi. GalUAase activity was confirmed to be absent from human cells. The substrate of GalUAase, galacturonic acid, is highly hydrophilic because of its anionic carboxylate group; high substrate hydrophilicity is an ideal characteristic for the substrate of an enzyme used for detection because it decreases nonspecific adsorption to biological samples. We show that E. tayi GalUAase could be used in the detection of antigen proteins on live human cells with lower background signal than the conventionally used enzyme ß-D-galactosidase. The combinatorial use of GalUAase with ß-D-galactosidase enabled simultaneous detection of two antigens on live cells.

Engineered macrophages acting as a trigger to induce inflammation only in tumor tissues based on arginase 1-responsive TNF-α accelerated release.

Herein, we report engineered macrophages, termed "MacTrigger," acting as a trigger to induce an inflammatory environment only in tumor tissues. This led to intensive anti-tumor effects based on the removal potential of foreign substances. The strength of this study is the utilization of two unique functions of macrophages: (1) their ability to migrate to tumor tissues and (2) polarization into the anti-inflammatory M2 phenotype in the presence of tumor tissues. The MacTrigger accelerated the release of inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), when it was polarized to the M2 phenotype. When the MacTrigger was administered to tumor-bearing mice, tumor growth was significantly inhibited compared with the non-treatment group, the un-transfected macrophages group, and the group with engineered macrophages capable of randomly releasing TNF-α. Additionally, the ratio of the M1 phenotype to the M2 phenotype in tumor tissues was >1 only in the MacTrigger group. Moreover, the ratios of natural killer cells and CD8+T cells in tumor tissues were increased compared with other groups. These results indicate that MacTrigger can induce inflammation in tumor tissues, leading to effective anti-tumor effects. In normal tissues, especially the liver, notable side effects were not observed. This is because, in the liver, the MacTrigger was not polarized to the M2 phenotype and could not induce inflammation. These results suggest that the MacTrigger is a "trigger" that can induce inflammation only in tumor tissues, then allowing the body to attack tumor tissues through the innate immunity system.

Engineered macrophages acting as a trigger to induce inflammation only in tumor tissues.

Herein, we report engineered macrophages, termed "MacTrigger," acting as a trigger to induce an inflammatory environment only in tumor tissues. This led to intensive anti-tumor effects based on the removal potential of foreign substances. The strength of this study is the utilization of two unique functions of macrophages: (1) their ability to migrate to tumor tissues and (2) polarization into the anti-inflammatory M2 phenotype in the presence of tumor tissues. The MacTrigger accelerated the release of inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), when it was polarized to the M2 phenotype. When the MacTrigger was administered to tumor-bearing mice, tumor growth was significantly inhibited compared with the non-treatment group, the un-transfected macrophages group, and the group with engineered macrophages capable of randomly releasing TNF-α. Additionally, the ratio of the M1 phenotype to the M2 phenotype in tumor tissues was >1 only in the MacTrigger group. Moreover, the ratios of natural killer cells and CD8+T cells in tumor tissues were increased compared with other groups. These results indicate that MacTrigger can induce inflammation in tumor tissues, leading to effective anti-tumor effects. In normal tissues, especially the liver, notable side effects were not observed. This is because, in the liver, the MacTrigger was not polarized to the M2 phenotype and could not induce inflammation. These results suggest that the MacTrigger is a "trigger" that can induce inflammation only in tumor tissues, then allowing the body to attack tumor tissues through the innate immunity system.