Establishment of an In Vivo Xenograft Mouse Model of a Subcutaneous Submillimeter HT-29 Tumor Formed from a Single Spheroid Transplanted Using Radiation-Crosslinked Gelatin Hydrogel Microwell

An In Vivo Dual-Observation Method to Monitor Tumor Mass and Tumor-Surface Blood Vessels for Developing Anti-Angiogenesis Agents against Submillimeter Tumors

Managing metastasis at the early stage and detecting and treating submillimeter tumors at early metastasis are crucial for improving cancer prognosis. Angiogenesis is a critical target for developing drugs to detect and inhibit submillimeter tumor growth; however, drug development remains challenging because there are no suitable models for observing the submillimeter tumor mass and the surrounding blood vessels in vivo. We have established a xenograft subcutaneous submillimeter tumor mouse model with HT-29-RFP by transplanting a single spheroid grown on radiation-crosslinked gelatin hydrogel microwells. Here, we developed an in vivo dual-observation method to observe the submillimeter tumor mass and tumor-surface blood vessels using this model. RFP was detected to observe the tumor mass, and a fluorescent angiography agent FITC-dextran was administered to observe blood vessels via stereoscopic fluorescence microscopy. The anti-angiogenesis agent regorafenib was used to confirm the usefulness of this method. This method effectively detected the submillimeter tumor mass and tumor-surface blood vessels in vivo. Regorafenib treatment revealed tumor growth inhibition and angiogenesis downregulation with reduced vascular extremities, segments, and meshes. Further, we confirmed that tumor-surface blood vessel areas monitored using in vivo dual-observation correlated with intratumoral blood vessel areas observed via fluorescence microscopy with frozen sections. In conclusion, this method would be useful in developing anti-angiogenesis agents against submillimeter tumors.

A Micro-Immunotherapy Sequential Medicine MIM-seq Displays Immunomodulatory Effects on Human Macrophages and Anti-Tumor Properties towards In Vitro 2D and 3D Models of Colon Carcinoma and in an In Vivo Subcutaneous Xenograft Colon Carcinoma Model

In this study, the immunomodulatory effects of a sequential micro-immunotherapy medicine, referred as MIM-seq, were appraised in human primary M1 and M2 macrophages, in which the secretion of pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, IL-12, IL-23, and tumor necrosis factor (TNF)-alpha, was inhibited. In addition, the potential anti-proliferative effects of MIM-seq on tumor cells was assessed in three models of colorectal cancer (CRC): an in vitro two-dimensions (2D) model of HCT-116 cells, an in vitro tri-dimensional (3D) model of spheroids, and an in vivo model of subcutaneous xenografted mice. In these models, MIM-seq displayed anti-proliferative effects when compared with the vehicle. In vivo, the tumor growth was slightly reduced in MIM-seq-treated animals. Moreover, MIM-seq could slightly reduce the growth of our spheroid models, especially under serum-deprivation. When MIM-seq was combined with two well-known anti-cancerogenic agents, either resveratrol or etoposide, MIM-seq could even further reduce the spheroid’s volume, pointing up the need to further assess whether MIM-seq could be beneficial for CRC patients as an adjuvant therapy. Altogether, these data suggest that MIM-seq could have anti-tumor properties against CRC and an immunomodulatory effect towards the mediators of inflammation, whose systemic dysregulation is considered to be a poor prognosis for patients.