DNA-barcoded signal amplification for imaging mass cytometry enables sensitive and highly multiplexed tissue imaging.

Imaging mass cytometry (IMC) is a highly multiplexed, antibody-based imaging method that captures heterogeneous spatial protein expression patterns at subcellular resolution. Here we report the extension of IMC to low-abundance markers through incorporation of the DNA-based signal amplification by exchange reaction, immuno-SABER. We applied SABER-IMC to image the tumor immune microenvironment in human melanoma by simultaneous imaging of 18 markers with immuno-SABER and 20 markers without amplification. SABER-IMC enabled the identification of immune cell phenotypic markers, such as T cell co-receptors and their ligands, that are not detectable with IMC.

Multielement Z-tag imaging by X-ray fluorescence microscopy for next-generation multiplex imaging.

Rapid, highly multiplexed, nondestructive imaging that spans the molecular to the supra-cellular scale would be a powerful tool for tissue analysis. However, the physical constraints of established imaging methods limit the simultaneous improvement of these parameters. Whole-organism to atomic-level imaging is possible with tissue-penetrant, picometer-wavelength X-rays. To enable highly multiplexed X-ray imaging, we developed multielement Z-tag X-ray fluorescence (MEZ-XRF) that can operate at kHz speeds when combined with signal amplification by exchange reaction (SABER)-amplified Z-tag reagents. We demonstrated parallel imaging of 20 Z-tag or SABER Z-tag reagents at subcellular resolution in cell lines and multiple human tissues. We benchmarked MEZ-XRF against imaging mass cytometry and demonstrated the nondestructive multiscale repeat imaging capabilities of MEZ-XRF with rapid tissue overview scans, followed by slower, more sensitive imaging of low-abundance markers such as immune checkpoint proteins. The unique multiscale, nondestructive nature of MEZ-XRF, combined with SABER Z-tags for high sensitivity or enhanced speed, enables highly multiplexed bioimaging across biological scales.

Single Cell Array Enclosed with a Photodegradable Hydrogel in Microwells for Image-Based Cell Classification and Selective Photorelease of Cells.

Single cell arrays provide an accurate classification of analyte cells through an image-based analysis of cellular phenotypes. Light-guided cell retrieval from a single cell array is a promising approach for the rapid and simple sorting of difficult to distinguish cells. In this study, we developed a single cell array enclosed with a photodegradable hydrogel in microwells to enable both comprehensive image-based single cell analysis and light-guided cell retrieval. In this system, individual cells became trapped in the microwells together with the photodegradable hydrogel at a high cell density on a chip regardless of cell type, adhesiveness, and motility. Fluorescence-stained model cells and vaccinated dendritic cells were identified by microscopic imaging and then selectively released through the light-induced degradation of the cell-embedding hydrogels. The target cells were selectively retrieved with a purity of >95% from the cell mixture through rapid photorelease, and the retrieved cells were confirmed to grow normally. Our results provide proof-of-principle that the photoresponsive microwell array serves as a versatile tool for image-based cell sorting in cellular researches and the manufacturing processes of high-performance cells.

Hepato-entrained B220+CD11c+NK1.1+ cells regulate pre-metastatic niche formation in the lung.

Primary tumours establish metastases by interfering with distinct organs. In pre-metastatic organs, a tumour-friendly microenvironment supports metastatic cells and is prepared by many factors including tissue resident cells, bone marrow-derived cells and abundant fibrinogen depositions. However, other components are unclear. Here, we show that a third organ, originally regarded as a bystander, plays an important role in metastasis by directly affecting the pre-metastatic soil. In our model system, the liver participated in lung metastasis as a leucocyte supplier. These liver-derived leucocytes displayed liver-like characteristics and, thus, were designated hepato-entrained leucocytes (HepELs). HepELs had high expression levels of coagulation factor X (FX) and vitronectin (Vtn) and relocated to fibrinogen-rich hyperpermeable regions in pre-metastatic lungs; the cells then switched their expression from Vtn to thrombospondin, both of which were fibrinogen-binding proteins. Cell surface marker analysis revealed that HepELs contained B220+CD11c+NK1.1+ cells. In addition, an injection of B220+CD11c+NK1.1+ cells successfully eliminated fibrinogen depositions in pre-metastatic lungs via FX Moreover, B220+CD11c+NK1.1+ cells demonstrated anti-metastatic tumour ability with IFNγ induction. These findings indicate that liver-primed B220+CD11c+NK1.1+ cells suppress lung metastasis.