Application of iPS cell-derived macrophages to cancer therapy

A tumor microenvironment-based classification of gastric cancer for more effective diagnosis and treatment

With approximately one million diagnosed cases and over 700,000 deaths recorded annually, gastric cancer (GC) is the third most common cause of cancer-related deaths worldwide. GC is a heterogeneous tumor. Thus, optimal management requires biomarkers of prognosis, treatment selection, and treatment response. The Cancer Genome Atlas program sub-classified GC into molecular subtypes, providing a framework for treatment personalization using traditional chemotherapies or biologics. Here, we report a comprehensive study of GC vascular and immune tumor microenvironment (TME)-based on stage and molecular subtypes of the disease and their correlation with outcomes. Using tissues and blood circulating biomarkers and a molecular classification, we identified cancer cell and tumor archetypes, which show that the TME evolves with the disease stage and is a major determinant of prognosis. Moreover, our TME-based subtyping strategy allowed the identification of archetype-specific prognostic biomarkers such as CDH1-mutant GC and circulating IL-6 that provided information beyond and independent of TMN staging, MSI status, and consensus molecular subtyping. The results show that integrating molecular subtyping with TME-specific biomarkers could contribute to improved patient prognostication and may provide a basis for treatment stratification, including for contemporary anti-angiogenesis and immunotherapy approaches.

Macrophages derived from pluripotent stem cells: prospective applications and research gaps

Induced pluripotent stem cells (iPSCs) represent a valuable cell source able to give rise to different cell types of the body. Among the various pathways of iPSC differentiation, the differentiation into macrophages is a recently developed and rapidly growing technique. Macrophages play a key role in the control of host homeostasis. Their dysfunction underlies many diseases, including hereditary, infectious, oncological, metabolic and other disorders. Targeting macrophage activity and developing macrophage-based cell therapy represent promising tools for the treatment of many pathological conditions. Macrophages generated from human iPSCs (iMphs) provide great opportunities in these areas. The generation of iMphs is based on a step-wise differentiation of iPSCs into mesoderm, hematopoietic progenitors, myeloid monocyte-like cells and macrophages. The technique allows to obtain standardizable populations of human macrophages from any individual, scale up macrophage production and introduce genetic modifications, which gives significant advantages over the standard source of human macrophages, monocyte-derived macrophages. The spectrum of iMph applications is rapidly growing. iMphs have been successfully used to model hereditary diseases and macrophage-pathogen interactions, as well as to test drugs. iMph use for cell therapy is another promising and rapidly developing area of research. The principles and the details of iMph generation have recently been reviewed. This review systemizes current and prospective iMph applications and discusses the problem of iMph safety and other issues that need to be explored before iMphs become clinically applicable.

The Potential of Induced Pluripotent Stem Cells to Advance the Treatment of Pancreatic Ductal Adenocarcinoma

Simple Summary

Despite improvements in the treatment of several cancer types, the extremely poor prognosis of pancreatic cancer patients has remained unchanged over the last decades. Therefore, new therapeutic regimens for pancreatic cancer are highly needed. In this review, we will discuss the potential of induced pluripotent stem cells (iPSCs) to generate representative pancreatic cancer models that can aid the development of novel diagnostics and therapeutic strategies. Furthermore, the potential of iPSCs as pancreatic cancer vaccines or as a basis for cellular therapies will be discussed. With promising preclinical results and ongoing clinical trials, the potential of iPSCs to further the treatment of pancreatic cancer is being explored and, in turn, will hopefully provide additional therapies to increase the poor survival rates of this patient population.

Abstract

Advances in the treatment of pancreatic ductal adenocarcinoma (PDAC) using neoadjuvant chemoradiotherapy, chemotherapy, and immunotherapy have had minimal impact on the overall survival of patients. A general lack of immunogenic features and a complex tumor microenvironment (TME) are likely culprits for therapy refractoriness in PDAC. Induced pluripotent stem cells (iPSCs) should be explored as a means to advance the treatment options for PDAC, by providing representative in vitro models of pancreatic cancer development. In addition, iPSCs could be used for tailor-made cellular immunotherapies or as a source of tumor-associated antigens in the context of vaccination.

Specific Blood Cells Derived from Pluripotent Stem Cells: An Emerging Field with Great Potential in Clinical Cell Therapy

Widely known for self-renewal and multilineage differentiation, stem cells can be differentiated into all specialized tissues and cells in the body. In the past few years, a number of researchers have focused on deriving hematopoietic stem cells (HSCs) from pluripotent stem cells (PSCs) as alternative sources for clinic. Existing findings demonstrated that it is feasible to obtain HSCs and certain mature blood lineages from PSCs, except for several issues to be addressed. This short review outlines the technologies used for hematopoietic differentiation in recent years. In addition, the therapeutic value of PSCs as a potential source of various blood cells is also discussed as well as its challenges and directions in future clinical applications.

Screening for new macrophage therapeutics

Myeloid derived macrophages play a key role in many human diseases, and their therapeutic modulation via pharmacological means is receiving considerable attention. Of particular interest is the fact that these cells are i) dynamic phenotypes well suited to therapeutic manipulation and ii) phagocytic, allowing them to be efficiently targeted with nanoformulations. However, it is important to consider that macrophages represent heterogeneous populations of subtypes with often competing biological behaviors and functions. In order to develop next generation therapeutics, it is therefore essential to screen for biological effects through a combination of in vitro and in vivo assays. Here, we review the state-of-the-art techniques, including both cell based screens and in vivo imaging tools that have been developed for assessment of macrophage phenotype. We conclude with a forward-looking perspective on the growing need for noninvasive macrophage assessment and laboratory assays to be put into clinical practice and the potential broader impact of myeloid-targeted therapeutics.

Human-induced pluripotent stem cell-derived macrophages and their immunological function in response to tuberculosis infection

BACKGROUND

Induced pluripotent stem cells (iPS) represent an innovative source for the standardized in vitro generation of macrophages (Mφ). Mφ show great promise in disease pathogenesis, particularly tuberculosis. However, there is no information about human iPS-derived (hiPS) macrophages (hiPS-Mφ) in response to tuberculosis infection.

METHODS

In the present study, macrophages derived from hiPS were established via embryoid body (EB) formation by using feeder-free culture conditions, and the human monocyte cell line THP-1 (THP-1-Mφ) was used as control. iPS-Mφ were characterized by using morphology, Giemsa staining, nonspecific esterase staining (α-NAE), phagocytosis, and surface phenotype. Additionally, after treatment with Bacillus Calmette-Guérin (BCG) for 24 h, cell apoptosis was detected by using an Annexin V-FITC Apoptosis Detection assay. The production of nitric oxide (NO), expression of tumor necrosis factor alpha (TNF-α), activity of apoptosis-related protein cysteine-3 (Caspase-3) and expression of B-cell lymphoma-2 (Bcl-2) were analyzed.

RESULTS

With respect to morphology, surface phenotype, and function, the iPS-Mφ closely resembled their counterparts generated in vitro from a human monocyte cell line. iPS-Mφ exhibited the typically morphological characteristics of macrophages, such as round, oval, fusiform and irregular characteristics. The cells were Giemsa-stained-positive, α-NAE-positive, and possessed phagocytic ability. iPS-Mφ express high levels of CD14, CD11b, CD40, CD68, and major histocompatibility complex II (MHC-II). Moreover, with regard to the apoptotic rate, the production of NO, expression of TNF-α, and activity of Caspase-3 and Bcl-2, iPS-Mφ closely resemble that of their counterparts generated in vitro from human monocyte cell line in response to BCG infection. The rate of apoptosis of BCG-treated iPS-Mφ was 37.77 ± 7.94% compared to that of the untreated group at 4.97 ± 1.60% (P < 0.01) by using Annexin V-FITC Apoptosis Detection. Additionally, the rate of apoptosis of BCG-treated THP-1-Mφ was 37.1 ± 2.84% compared to that of the untreated group at 6.19 ± 1.68% (P < 0.001). The expression of TNF-α and the production of NO were significantly increased (P < 0.001), and the activity of Caspase-3 was increased. However, the expression of Bcl-2 was inhibited (P < 0.001).

CONCLUSIONS

Our results demonstrate that Mφ derived from hiPS perform the immunological function in response to Bacillus Calmette-Guérin infection by undergoing apoptosis, increasing the production of NO and expression of TNF-α. Thus, our study may help to overcome the limitations of research into certain rare diseases due to the lack of adequate supply of disease-specific primary cells.

A Simple Multistep Protocol for Differentiating Human Induced Pluripotent Stem Cells into Functional Macrophages

Macrophages differentiated from human induced pluripotent stem cells (hiPSCs) provide an alternative new tool overcoming some of the limitations of existing models for human macrophages, such as human macrophage-like cell lines and primary monocyte-derived macrophages. A combination of different cytokines and growth factors can differentiate hiPSCs toward myeloid lineage. Here we describe a simple multistep protocol for differentiating hiPSCs into functional macrophages. This includes derivation of three germ-line containing embryoid bodies (EBs) from iPSCs, generation of myeloid precursors from EBs, and finally maturation of myeloid precursors into functional macrophages. Technical procedure and specific culture conditions associated with each of these steps are discussed in detail.

Induced pluripotent stem cell derived macrophages as a cellular system to study salmonella and other pathogens

A number of pathogens, including several human-restricted organisms, persist and replicate within macrophages (Mφs) as a key step in pathogenesis. The mechanisms underpinning such host-restricted intracellular adaptations are poorly understood, in part, due to a lack of appropriate model systems. Here we explore the potential of human induced pluripotent stem cell derived macrophages (iPSDMs) to study such pathogen interactions. We show iPSDMs express a panel of established Mφ-specific markers, produce cytokines, and polarise into classical and alternative activation states in response to IFN-γ and IL-4 stimulation, respectively. iPSDMs also efficiently phagocytosed inactivated bacterial particles as well as live Salmonella Typhi and S. Typhimurium and were able to kill these pathogens. We conclude that iPSDMs can support productive Salmonella infection and propose this as a flexible system to study host/pathogen interactions. Furthermore, iPSDMs can provide a flexible and practical cellular platform for assessing host responses in multiple genetic backgrounds.