An integrated enrichment system to facilitate isolation and molecular characterization of single cancer cells from whole blood

CD8+ T cell-mediated rejection of allogenic human-induced pluripotent stem cell-derived cardiomyocyte sheets in human PBMC-transferred NOG MHC double knockout mice

BACKGROUND

Transplantation of human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) has emerged as a promising therapy to treat end-stage heart failure. However, the immunogenicity of hiPS-CMs in transplanted patients has not been fully elucidated. Thus, in vivo models are required to estimate immune responses against hiPS-CMs in transplant recipients.

METHODS

We transferred human peripheral blood mononuclear cells (hPBMCs) into NOD/Shi-scid IL-2rgnull (NOG) MHC class I/II double knockout (NOG-ΔMHC) mice, which were reported to accept hPBMCs without xenogeneic-graft-versus-host disease (xeno-GVHD). Then, hiPS-CM sheets generated from the hiPS cell line 201B7 harboring a luciferase transgene were transplanted into the subcutaneous space of NOG-ΔMHC mice. Graft survival was monitored by bioluminescent images using a Xenogen In Vivo Imaging System.

RESULTS

The human immune cells were engrafted for more than 3 months in NOG-ΔMHC mice without lethal xeno-GVHD. The hiPS-CMs expressed a moderate level of human leukocyte antigen (HLA)-class I, but not HLA-class II, molecules even after interferon-gamma (IFN-γ) stimulation. Consistently, the allogenic IFN-γ-treated hiPS-CMs induced weak CD8+ but not CD4+ T cell responses in vitro. hiPS-CM sheets disappeared approximately 17 to 24 days after transplantation in hPBMC-transferred NOG-ΔMHC mice, and CD8+ T cell depletion significantly prolonged graft survival, similar to what was observed following tacrolimus treatment.

CONCLUSIONS

hiPS-CMs are less immunogenic in vitro but induce sufficient CD8+ T cell-mediated immune responses for graft rejection in vivo.

Deciphering the Biology of Circulating Tumor Cells through Single-Cell RNA Sequencing: Implications for Precision Medicine in Cancer

Circulating tumor cells (CTCs) hold unique biological characteristics that directly involve them in hematogenous dissemination. Studying CTCs systematically is technically challenging due to their extreme rarity and heterogeneity and the lack of specific markers to specify metastasis-initiating CTCs. With cutting-edge technology, single-cell RNA sequencing (scRNA-seq) provides insights into the biology of metastatic processes driven by CTCs. Transcriptomics analysis of single CTCs can decipher tumor heterogeneity and phenotypic plasticity for exploring promising novel therapeutic targets. The integrated approach provides a perspective on the mechanisms underlying tumor development and interrogates CTCs interactions with other blood cell types, particularly those of the immune system. This review aims to comprehensively describe the current study on CTC transcriptomic analysis through scRNA-seq technology. We emphasize the workflow for scRNA-seq analysis of CTCs, including enrichment, single cell isolation, and bioinformatic tools applied for this purpose. Furthermore, we elucidated the translational knowledge from the transcriptomic profile of individual CTCs and the biology of cancer metastasis for developing effective therapeutics through targeting key pathways in CTCs.

Immunophenotyping: Analytical approaches and role in preclinical development of nanomedicines

Pharmaceutical products can activate immune cells, suppress their function, or change the immune responses to traditional immunologically active agonists such as those present in microbes. Therefore, the assessment of immunostimulation, immunosuppression, and immunomodulation comprises the backbone of immunotoxicity studies of new drug entities. Depending on physicochemical properties (e.g., size, charge, surface functionalities, hydrophobicity), nanoparticles can be immunostimulatory, immunosuppressive, and immunomodulatory. Various methods and experimental frameworks have been established to support preclinical translational studies of nanotechnology-based drug products. Immunophenotyping after the exposure of cells or preclinical animal models to nanoparticles can provide critical information about the changes in both the numbers of immune cells and their activation status. However, this methodology is underutilized in preclinical studies of engineered nanomaterials. Herein, we review current literature about varieties of instrumentation and methods utilized for immunophenotyping, discuss their advantages and limitations, and propose a roadmap for applying immunophenotyping to support preclinical immunological characterization of nanotechnology-based formulations.

Design and Clinical Application of an Integrated Microfluidic Device for Circulating Tumor Cells Isolation and Single-Cell Analysis

Circulating tumor cells (CTCs) have been considered as an alternative to tissue biopsy for providing both germline-specific and tumor-derived genetic variations. Single-cell analysis of CTCs enables in-depth investigation of tumor heterogeneity and individualized clinical assessment. However, common CTC enrichment techniques generally have limitations of low throughput and cell damage. Herein, based on micropore-arrayed filtration membrane and microfluidic chip, we established an integrated CTC isolation platform with high-throughput, high-efficiency, and less cell damage. We observed a capture rate of around 85% and a purity of 60.4% by spiking tumor cells (PC-9) into healthy blood samples. Detection of CTCs from lung cancer patients demonstrated a positive detectable rate of 87.5%. Additionally, single CTCs, ctDNA and liver biopsy tissue of a representative advanced lung cancer patient were collected and sequenced, which revealed comprehensive genetic information of CTCs while reflected the differences in genetic profiles between different biological samples. This work provides a promising tool for CTCs isolation and further analysis at single-cell resolution with potential clinical value.

Neutrophils: Accomplices in metastasis

Metastasis is a critical cause of treatment failure and death in patients with advanced malignancies. Tumor cells can leave the primary site and enter the bloodstream; these circulating tumor cells then colonize target organs by overcoming blood shear stress, evading immune surveillance, and silencing the offensive capabilities of immune cells, eventually forming metastatic foci. From leaving the primary focus to the completion of distant metastasis, malignant tumor cells are supported and/or antagonized by certain immune cells. In particular, it has been found that myeloid granulocytes play an important role in this process. This review therefore aims to comprehensively describe the significance of neutrophils in solid tumor metastasis in terms of their supporting role in initiating the invasion and migration of tumor cells and assisting the colonization of circulating tumor cells in distant target organs, with the hope of providing insight into and ideas for anti-tumor metastasis treatment of tumor patients.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition)

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.

Rare Event Phenotyping and Molecular Characterization: Circulating Tumor Cells

Noninvasive isolation of circulating tumor cells (CTCs) from patient blood samples allows for interrogation of valuable molecular and phenotypic information useful for disease diagnosis and monitoring response to therapy. However, CTCs are extremely rare relative to red and white blood cells (R/WBC), thus making CTC isolation from unmanipulated whole blood very time-consuming. Moreover, single CTC analysis often requires hand-picking, a step that can result in more CTC loss and compromised cell integrity. Here we describe an automated flow cytometry-based approach for isolation and analysis of single, viable CTCs that combines gentle RBC lysis and magnetic, no-wash negative-depletion of WBCs, followed by a highly adaptable sorting protocol for rare cells of interest. Multiparametric flow-cytometric panels allow probing of numerous extracellular markers for immunophenotyping, while whole transcriptome analysis contributes to molecular characterization of individual CTCs. Index sorting links single CTC proteogenomics information.

Self-Seeding Microwells to Isolate and Assess the Viability of Single Circulating Tumor Cells

The availability of viable tumor cells could significantly improve the disease management of cancer patients. Here we developed and evaluated a method using self-seeding microwells to obtain single circulating tumor cells (CTC) and assess their potential to expand. Conditions were optimized using cells from the breast cancer cell line MCF-7 and blood from healthy volunteers collected in EDTA blood collection tubes. 43% of the MCF-7 cells (nucleus+, Ethidium homodimer-1-, Calcein AM+, α-EpCAM+, α-CD45-) spiked into 7.5 mL of blood could be recovered with 67% viability and these could be further expanded. The same procedure tested in metastatic breast and prostate cancer patients resulted in a CTC recovery of only 0–5% as compared with CTC counts obtained with the CellSearch^® system. Viability of the detected CTC ranged from 0–36%. Cell losses could be mainly contributed to the smaller size and greater flexibility of CTC as compared to cultured cells from cell lines and loss during leukocyte depletion prior to cell seeding. Although CTC losses can be reduced by fixation, to obtain viable CTC no fixatives can be used and pore size in the bottom of microwells will need to be reduced, filtration conditions adapted and pre-enrichment improved to reduce CTC losses.