Humanized mouse models: Application to human diseases

Chitinase-3-like-1: a multifaceted player in neuroinflammation and degenerative pathologies with therapeutic implications

Chitinase-3-like-1 (CHI3L1) is an evolutionarily conserved protein involved in key biological processes, including tissue remodeling, angiogenesis, and neuroinflammation. It has emerged as a significant player in various neurodegenerative diseases and brain disorders. Elevated CHI3L1 levels have been observed in neurological conditions such as traumatic brain injury (TBI), Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS), Creutzfeldt-Jakob disease (CJD), multiple sclerosis (MS), Neuromyelitis optica (NMO), HIV-associated dementia (HAD), Cerebral ischemic stroke (CIS), and brain tumors. This review explores the role of CHI3L1 in the pathogenesis of these disorders, with a focus on its contributions to neuroinflammation, immune cell infiltration, and neuronal degeneration. As a key regulator of neuroinflammation, CHI3L1 modulates microglia and astrocyte activity, driving the release of proinflammatory cytokines that exacerbate disease progression. In addition to its role in disease pathology, CHI3L1 has emerged as a promising biomarker for the diagnosis and monitoring of brain disorders. Elevated cerebrospinal fluid (CSF) levels of CHI3L1 have been linked to disease severity and cognitive decline, particularly in AD and MS, highlighting its potential for clinical diagnostics. Furthermore, therapeutic strategies targeting CHI3L1, such as small-molecule inhibitors and neutralizing antibodies, have shown promise in preclinical studies, demonstrating reduced neuroinflammation, amyloid plaque accumulation, and improved neuronal survival. Despite its therapeutic potential, challenges remain in developing selective and safe CHI3L1-targeted therapies, particularly in ensuring effective delivery across the blood-brain barrier and mitigating off-target effects. This review addresses the complexities of targeting CHI3L1, highlights its potential in precision medicine, and outlines future research directions aimed at unlocking its full therapeutic potential in treating neurodegenerative diseases and brain pathologies.

Humanized In Vivo Bone Tissue Engineering: In Vitro Preculture Conditions Control the Structural, Cellular, and Matrix Composition of Humanized Bone Organs

Bone tissue engineering (BTE) has long sought to elucidate the key factors controlling human/humanized bone formation for regenerative medicine and disease modeling applications, yet with no definitive answers due to the high number and co-dependency of parameters. This study aims to clarify the relative impacts of in vitro biomimetic 'preculture composition' and 'preculture duration' before in vivo implantation as key criteria for the optimization of BTE design. These parameters are directly related to in vitro osteogenic differentiation (OD) and mineralization and are being investigated across different osteoprogenitor-loaded biomaterials, specifically fibrous calcium phosphate-polycaprolactone (CaP-mPCL) scaffolds and gelatin methacryloyl (GelMA) hydrogels. The results show that OD and mineralization levels prior to implantation, enhanced by a mineralization medium supplement to the osteogenic medium (OM), significantly improve ectopic BTE outcomes, regardless of the biomaterial type. Specifically, preculture conditions are pivotal in achieving more faithful mimicry of human bone structure, cellular and extracellular matrix composition and organization, and provide control over bone marrow composition. This work emphasizes the potential of using biomimetic culture compositions, specifically the addition of a mineralization medium as a cost-effective and straightforward approach to enhance BTE outcomes, facilitating rapid development of bone models with superior quality and resemblance to native bone.

Role of cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathway in diabetes and its complications

Diabetes mellitus (DM) is one of the major causes of mortality worldwide, with inflammation being an important factor in its onset and development. This review summarizes the specific mechanisms of the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway in mediating inflammatory responses. Furthermore, it comprehensively presents related research progress and the subsequent involvement of this pathway in the pathogenesis of early-stage DM, diabetic gastroenteropathy, diabetic cardiomyopathy, non-alcoholic fatty liver disease, and other complications. Additionally, the role of cGAS-STING in autonomic dysfunction and intestinal dysregulation, which can lead to digestive complications, has been discussed. Altogether, this study provides a comprehensive analysis of the research advances regarding the cGAS-STING pathway-targeted therapeutic agents and the prospects for their application in the precision treatment of DM.

Dynamic microphysiological system chip platform for high-throughput, customizable, and multi-dimensional drug screening

Spheroids and organoids have attracted significant attention as innovative models for disease modeling and drug screening. By employing diverse types of spheroids or organoids, it is feasible to establish microphysiological systems that enhance the precision of disease modeling and offer more dependable and comprehensive drug screening. High-throughput microphysiological systems that support optional, parallel testing of multiple drugs have promising applications in personalized medical treatment and drug research. However, establishing such a system is highly challenging and requires a multidisciplinary approach. This study introduces a dynamic Microphysiological System Chip Platform (MSCP) with multiple functional microstructures that encompass the mentioned advantages. We developed a high-throughput lung cancer spheroids model and an intestine-liver-heart-lung cancer microphysiological system for conducting parallel testing on four anti-lung cancer drugs, demonstrating the feasibility of the MSCP. This microphysiological system combines microscale and macroscale biomimetics to enable a comprehensive assessment of drug efficacy and side effects. Moreover, the microphysiological system enables evaluation of the real pharmacological effect of drug molecules reaching the target lesion after absorption by normal organs through fluid-based physiological communication. The MSCP could serves as a valuable platform for microphysiological system research, making significant contributions to disease modeling, drug development, and personalized medical treatment.

Human CD56+CD39+ dNK cells support fetal survival through controlling trophoblastic cell fate: immune mechanisms of recurrent early pregnancy loss

Decidual natural killer (dNK) cells are the most abundant immune cells at the maternal-fetal interface during early pregnancy in both mice and humans, and emerging single-cell transcriptomic studies have uncovered various human dNK subsets that are disrupted in patients experiencing recurrent early pregnancy loss (RPL) at early gestational stage, suggesting a connection between abnormal proportions or characteristics of dNK subsets and RPL pathogenesis. However, the functional mechanisms underlying this association remain unclear. Here, we established a mouse model by adoptively transferring human dNK cells into pregnant NOG (NOD/Shi-scid/IL-2Rγnull) mice, where human dNK cells predominantly homed into the uteri of recipients. Using this model, we observed a strong correlation between the properties of human dNK cells and pregnancy outcome. The transfer of dNK cells from RPL patients (dNK-RPL) remarkably worsened early pregnancy loss and impaired placental trophoblast cell differentiation in the recipients. These adverse effects were effectively reversed by transferring CD56+CD39+ dNK cells. Mechanistic studies revealed that CD56+CD39+ dNK subset facilitates early differentiation of mouse trophoblast stem cells (mTSCs) towards both invasive and syncytial pathways through secreting macrophage colony-stimulating factor (M-CSF). Administration of recombinant M-CSF to NOG mice transferred with dNK-RPL efficiently rescued the exacerbated pregnancy outcomes and fetal/placental development. Collectively, this study established a novel humanized mouse model featuring functional human dNK cells homing into the uteri of recipients and uncovered the pivotal role of M-CSF in fetal-supporting function of CD56+CD39+ dNK cells during early pregnancy, highlighting that M-CSF may be a previously unappreciated therapeutic target for intervening RPL.

Engraftment of adult hematopoietic stem and progenitor cells in a novel model of humanized mice

Pre-clinical use of humanized mice transplanted with CD34+ hematopoietic stem and progenitor cells (HSPCs) is limited by insufficient engraftment with adult non-mobilized HSPCs. Here, we developed a novel immunodeficient mice based on NOD-SCID-Il2γc-/- (NSG) mice to support long-term engraftment with human adult HSPCs. As both Flt3L and IL-6 are critical for many aspects of hematopoiesis, we knock-out mouse Flt3 and knock-in human IL6 gene. The resulting mice showed an increase in the availability of mouse Flt3L to human cells and a dose-dependent production of human IL-6 upon activation. Upon transplantation with low number of human HSPCs from adult bone marrow, these humanized mice demonstrated a significantly higher engraftment with multilineage differentiation of human lymphoid and myeloid cells, and tissue colonization at one year after adult HSPC transplant. Thus, these mice enable studies of human hematopoiesis and tissue colonization over time and may facilitate building autologous models for immuno-oncology studies.

Progress, implications, and challenges in using humanized immune system mice in CAR-T therapy-Application evaluation and improvement

In recent years, humanized immune system (HIS) mice have been gradually used as models for preclinical research in pharmacotherapies and cell therapies with major breakthroughs in tumor and other fields, better mimicking the human immune system and the tumor immune microenvironment, compared to traditional immunodeficient mice. To better promote the application of HIS mice in preclinical research, we selectively summarize the current prevalent and breakthrough research and evaluation of chimeric antigen receptor (CAR) -T cells in various antiviral and antitumor treatments. By exploring its application in preclinical research, we find that it can better reflect the actual clinical patient condition, with the advantages of providing high-efficiency detection indicators, even for progressive research and development. We believe that it has better clinical patient simulation and promotion for the updated design of CAR-T cell therapy than directly transplanted immunodeficient mice. The characteristics of the main models are proposed to improve the use defects of the existing models by reducing the limitation of antihost reaction, combining multiple models, and unifying sources and organoid substitution. Strategy study of relapse and toxicity after CAR-T treatment also provides more possibilities for application and development.

Humanized mouse models for inherited thrombocytopenia studies

Inherited thrombocytopenia (IT) is a group of hereditary disorders characterized by a reduced platelet count as the main clinical manifestation, and often with abnormal platelet function, which can subsequently lead to impaired hemostasis. In the past decades, humanized mouse models (HMMs), that are mice engrafted with human cells or genes, have been widely used in different research areas including immunology, oncology, and virology. With advances of the development of immunodeficient mice, the engraftment, and reconstitution of functional human platelets in HMM permit studies of occurrence and development of platelet disorders including IT and treatment strategies. This article mainly reviews the development of humanized mice models, the construction methods, research status, and problems of using humanized mice for the in vivo study of human thrombopoiesis.

Long-term engraftment of adult hematopoietic progenitors in a novel model of humanized mice

Pre-clinical use of humanized mice transplanted with CD34 + hematopoietic progenitor cells (HPCs) is limited by insufficient engraftment with adult HPCs. Here, we developed a novel immunodeficient mice based in NOD-SCID- Il2γc -/- (NSG) mice to support long-term engraftment with human adult HPCs and tissue colonization with human myeloid cells. As both Flt3L and IL-6 are critical for many aspects of hematopoiesis, we knock-out mouse Flt3 and knock-in human IL6 gene. The resulting mice showed an increase in the availability of mouse Flt3L to human cells, and a dose-dependent production of human IL-6 upon activation. Upon transplantation with low number of human HPCs from adult bone marrow, these humanized mice demonstrated a significantly higher engraftment with multilineage differentiation of human lymphoid and myeloid cells. Furthermore, higher frequencies of human lymphoid and myeloid cells were detected in tissues at one year after adult HPC transplant. Thus, these mice enable studies of human hematopoiesis and tissue colonization over time.

Summary

Pre-clinical use of humanized mice is limited by insufficient engraftment with adult hematopoietic progenitor cells (HPCs). Here, we developed a novel immunodeficient mice which support long-term engraftment with adult bone marrow HPCs and facilitate building autologous models for immuno-oncology studies.

Progress in building clinically relevant patient-derived tumor xenograft models for cancer research

Patient-derived tumor xenograft (PDX) models, a method involving the surgical extraction of tumor tissues from cancer patients and subsequent transplantation into immunodeficient mice, have emerged as a pivotal approach in translational research, particularly in advancing precision medicine. As the first stage of PDX development, the patient-derived orthotopic xenograft (PDOX) models implant tumor tissue in mice in the corresponding anatomical locations of the patient. The PDOX models have several advantages, including high fidelity to the original tumor, heightened drug sensitivity, and an elevated rate of successful transplantation. However, the PDOX models present significant challenges, requiring advanced surgical techniques and resource-intensive imaging technologies, which limit its application. And then, the humanized mouse models, as well as the zebrafish models, were developed. Humanized mouse models contain a human immune environment resembling the tumor and immune system interplay. The humanized mouse models are a hot topic in PDX model research. Regarding zebrafish patient-derived tumor xenografts (zPDX) and patient-derived organoids (PDO) as promising models for studying cancer and drug discovery, zPDX models are used to transplant tumors into zebrafish as novel personalized medical animal models with the advantage of reducing patient waiting time. PDO models provide a cost-effective approach for drug testing that replicates the in vivo environment and preserves important tumor-related information for patients. The present review highlights the functional characteristics of each new phase of PDX and provides insights into the challenges and prospective developments in this rapidly evolving field.

Unlocking Translational Potential: Conditionally Reprogrammed Cells in Advancing Breast Cancer Research

Preclinical in vitro models play an important role in studying cancer cell biology and facilitating translational research, especially in the identification of drug targets and drug discovery studies. This is particularly relevant in breast cancer, where the global burden of disease is quite high based on prevalence and a relatively high rate of lethality. Predictive tools to select patients who will be responsive to invasive or morbid therapies (radiotherapy, chemotherapy, immunotherapy, and/or surgery) are relatively lacking. To be clinically relevant, a model must accurately replicate the biology and cellular heterogeneity of the primary tumor. Addressing these requirements and overcoming the limitations of most existing cancer cell lines, which are typically derived from a single clone, we have recently developed conditional reprogramming (CR) technology. The CR technology refers to a co-culture system of primary human normal or tumor cells with irradiated murine fibroblasts in the presence of a Rho-associated kinase inhibitor to allow the primary cells to acquire stem cell properties and the ability to proliferate indefinitely in vitro without any exogenous gene or viral transfection. This innovative approach fulfills many of these needs and offers an alternative that surpasses the deficiencies associated with traditional cancer cell lines. These CR cells (CRCs) can be reprogrammed to maintain a highly proliferative state and reproduce the genomic and histological characteristics of the parental tissue. Therefore, CR technology may be a clinically relevant model to test and predict drug sensitivity, conduct gene profile analysis and xenograft research, and undertake personalized medicine. This review discusses studies that have applied CR technology to conduct breast cancer research.

Thymocyte Development of Humanized Mice Is Promoted by Interactions with Human-Derived Antigen Presenting Cells upon Immunization

Immune responses in humanized mice are generally inefficient without co-transplantation of human thymus or HLA transgenes. Previously, we generated humanized mice via the intra-bone marrow injection of CD133+ cord blood cells into irradiated adult immunodeficient mice (IBMI-huNSG mice), which could mount functional immune responses against HTLV-1, although the underlying mechanisms were still unknown. Here, we investigated thymocyte development in IBMI-huNSG mice, focusing on the roles of human and mouse MHC restriction. IBMI-huNSG mice had normal developmental profiles but aberrant thymic structures. Surprisingly, the thymic medulla-like regions expanded after immunization due to enhanced thymocyte expansion in association with the increase in HLA-DR+ cells, including CD205⁺ dendritic cells (DCs). The organ culture of thymus from immunized IBMI-huNSG mice with a neutralizing antibody to HLA-DR showed the HLA-DR-dependent expansion of CD4 single positive thymocytes. Mature peripheral T-cells exhibited alloreactive proliferation when co-cultured with human peripheral blood mononuclear cells. Live imaging of the thymus from immunized IBMI-huNSG mice revealed dynamic adhesive contacts of human-derived thymocytes and DCs accompanied by Rap1 activation. These findings demonstrate that an increase in HLA-DR+ cells by immunization promotes HLA-restricted thymocyte expansion in humanized mice, offering a unique opportunity to generate humanized mice with ease.

Review of the Immune Checkpoint Inhibitors in the Context of Cancer Treatment

Checkpoint proteins are an integral part of the immune system and are used by the tumor cells to evade immune response, which helps them grow uncontrollably. By blocking these proteins, immune checkpoint inhibitors can restore the capability of the immune system to attack cancer cells and stop their growth. These findings are backed by adequate clinical trial data and presently, several FDA-approved immune checkpoint inhibitors exist in the market for treating various types of cancers, including melanoma, hepatocellular, endometrial, lung, kidney and others. Their mode of action is inhibition by targeting the checkpoint proteins CTLA-4, PD-1, PD-L1, etc. They can be used alone as well as in amalgamation with other cancer treatments, like surgery, radiation or chemotherapy. Since these drugs target only specific immune system proteins, their side effects are reduced in comparison with the traditional chemotherapy drugs, but may still cause a few affects like fatigue, skin rashes, and fever. In rare cases, these inhibitors are known to have caused more serious side effects, such as cardiotoxicity, and inflammation in the intestines or lungs. Herein, we provide an overview of these inhibitors and their role as biomarkers, immune-related adverse outcomes and clinical studies in the treatment of various cancers, as well as present some future perspectives.

Conditional Reprogramming Modeling of Bladder Cancer for Clinical Translation

The use of advanced preclinical models has become increasingly important in drug development. This is particularly relevant in bladder cancer, where the global burden of disease is quite high based on prevalence and a relatively high rate of lethality. Predictive tools to select patients who will be responsive to invasive or morbid therapies (chemotherapy, radiotherapy, immunotherapy, and/or surgery) are largely absent. Patient-derived and clinically relevant models including patient-derived xenografts (PDX), organoids, and conditional reprogramming (CR) of cell cultures efficiently generate numerous models and are being used in both basic and translational cancer biology. These CR cells (CRCs) can be reprogrammed to maintain a highly proliferative state and reproduce the genomic and histological characteristics of the parental tissue. Therefore, CR technology may be a clinically relevant model to test and predict drug sensitivity, conduct gene profile analysis and xenograft research, and undertake personalized medicine. This review discusses studies that have utilized CR technology to conduct bladder cancer research.

Generation, evolution, interfering factors, applications, and challenges of patient-derived xenograft models in immunodeficient mice

Establishing appropriate preclinical models is essential for cancer research. Evidence suggests that cancer is a highly heterogeneous disease. This follows the growing use of cancer models in cancer research to avoid these differences between xenograft tumor models and patient tumors. In recent years, a patient-derived xenograft (PDX) tumor model has been actively generated and applied, which preserves both cell-cell interactions and the microenvironment of tumors by directly transplanting cancer tissue from tumors into immunodeficient mice. In addition to this, the advent of alternative hosts, such as zebrafish hosts, or in vitro models (organoids and microfluidics), has also facilitated the advancement of cancer research. However, they still have a long way to go before they become reliable models. The development of immunodeficient mice has enabled PDX to become more mature and radiate new vitality. As one of the most reliable and standard preclinical models, the PDX model in immunodeficient mice (PDX-IM) exerts important effects in drug screening, biomarker development, personalized medicine, co-clinical trials, and immunotherapy. Here, we focus on the development procedures and application of PDX-IM in detail, summarize the implications that the evolution of immunodeficient mice has brought to PDX-IM, and cover the key issues in developing PDX-IM in preclinical studies.

The Chorioallantoic Membrane Xenograft Assay as a Reliable Model for Investigating the Biology of Breast Cancer

The chorioallantoic membrane (CAM) assay is an alternative in vivo model that allows for minimally invasive research of cancer biology. Using the CAM assay, we investigated phenotypical and functional characteristics (tumor grade, mitosis rate, tumor budding, hormone receptor (HR) and HER2 status, Ki-67 proliferation index) of two breast cancer cell lines, MCF-7 and MDA-MB-231, which resemble the HR+ (luminal) and triple-negative breast cancer (TNBC) subgroups, respectively. Moreover, the CAM results were directly compared with murine MCF-7- and MDA-MB-231-derived xenografts and human patient TNBC tissue. Known phenotypical and biological features of the aggressive triple-negative breast cancer cell line (MDA-MB-231) were confirmed in the CAM assay, and mouse xenografts. Furthermore, the histomorphological and immunohistochemical variables assessed in the CAM model were similar to those in human patient tumor tissue. Given the confirmation of the classical biological and growth properties of breast cancer cell lines in the CAM model, we suggest this in vivo model to be a reliable alternative test system for breast cancer research to reduce murine animal experiments.

Evolution of 3D Cultures: Toward Tailored Preclinical Models

The identification and validation of simple, reliable and reproducible three dimensional (3D) in vitro culture systems represent a major challenge in the field of anticancer drug development [...].

Short-term carcinogenicity study of N-methyl-N-nitrosourea in FVB-Trp53 heterozygous mice

Carcinogenicity tests predict the tumorigenic potential of various substances in the human body by studying tumor induction in experimental animals. There is a need for studies that explore the use of FVB/N-Trp53em2Hwl/Korl (FVB-Trp53+/-) mice, created by TALEN-mediated gene targeting in Korea, in carcinogenicity tests. This study was performed to determine whether FVB-Trp53+/- mice are a suitable model for short-term carcinogenicity studies. To compare the carcinogenicity at different concentrations, 25, 50, and 75 mg/kg of N-methyl-N-nitrosourea (MNU), a known carcinogen, were administered intraperitoneally to FVB-Trp53+/- and wild-type male mice. After 26 weeks, the survival rate was significantly reduced in FVB-Trp53+/- mice compared to the wild-type mice in the 50 and 75 mg/kg groups. The incidence of thymic malignant lymphoma (TML) in the 50 and 75 mg/kg groups was 54.2 and 59.1% in FVB-Trp53+/- male mice, respectively. TML metastasized to the lungs, spleen, lymph nodes, liver, kidney, and heart in FVB-Trp53+/- male mice. Furthermore, the incidence of primary lung tumors, such as adenomas and adenocarcinomas, was 65.4, 62.5, and 45.4% in the FVB-Trp53+/- mice of the 25, 50, and 75 mg/kg groups, respectively. The main tumor types in FVB-Trp53+/- mice were TML and primary lung tumors, regardless of the dose of MNU administered. These results suggest that systemic tumors may result from malfunctions in the p53 gene and pathway, which is an important factor in the pathogenesis of human cancers. Therefore, FVB-Trp53 heterozygous mice are suitable for short-term carcinogenicity tests using positive carcinogens, and that the best result using MNU, a positive carcinogen, might have a single dose of 50 mg/kg.

Insights into mechanisms of graft-versus-host disease through humanised mouse models

Graft-versus-host disease (GVHD) is a major complication that occurs following allogeneic haematopoietic stem cell transplantation (HSCT) for the treatment of haematological cancers and other blood-related disorders. GVHD is an inflammatory disorder, where the transplanted donor immune cells can mediate an immune response against the recipient and attack host tissues. Despite over 60 years of research, broad-range immune suppression is still used to prevent or treat GVHD, leading to an increased risk of cancer relapse and infection. Therefore, further insights into the disease mechanisms and development of predictive and prognostic biomarkers are key to improving outcomes and reducing GVHD development following allogeneic HSCT. An important preclinical tool to examine the pathophysiology of GVHD and to understand the key mechanisms that lead to GVHD development are preclinical humanised mouse models. Such models of GVHD are now well-established and can provide valuable insights into disease development. This review will focus on models where human peripheral blood mononuclear cells are injected into immune-deficient non-obese diabetic (NOD)-scid-interleukin-2(IL-2)Rγ mutant (NOD-scid-IL2Rγ^null) mice. Humanised mouse models of GVHD can mimic the clinical setting for GVHD development, with disease progression and tissues impacted like that observed in humans. This review will highlight key findings from preclinical humanised mouse models regarding the role of donor human immune cells, the function of cytokines and cell signalling molecules and their impact on specific target tissues and GVHD development. Further, specific therapeutic strategies tested in these preclinical models reveal key molecular pathways important in reducing the burden of GVHD following allogeneic HSCT.

Mouse Models of Hepatocellular Carcinoma: Classification, Advancement, and Application

Hepatocellular carcinoma (HCC) is the subtype of liver cancer with the highest incidence, which is a heterogeneous malignancy with increasing incidence rate and high mortality. For ethical reasons, it is essential to validate medical clinical trials for HCC in animal models before further consideration on humans. Therefore, appropriate models for the study of the pathogenesis of the disease and related treatment methods are necessary. For tumor research, mouse models are the most commonly used and effective in vivo model, which is closer to the real-life environment, and the repeated experiments performed on it are closer to the real situation. Several mouse models of HCC have been developed with different mouse strains, cell lines, tumor sites, and tumor formation methods. In this review, we mainly introduce some mouse HCC models, including induced model, gene-edited model, HCC transplantation model, and other mouse HCC models, and discuss how to choose the appropriate model according to the purpose of the experiments.

MRSA Infection in the Thigh Muscle Leads to Systemic Disease, Strong Inflammation, and Loss of Human Monocytes in Humanized Mice

MRSA (Methicillin-resistant Staphylococcus aureus) is the second-leading cause of deaths by antibiotic-resistant bacteria globally, with more than 100,000 attributable deaths annually. Despite the high urgency to develop a vaccine to control this pathogen, all clinical trials with pre-clinically effective candidates failed so far. The recent development of “humanized” mice might help to edge the pre-clinical evaluation closer to the clinical situation and thus close this gap. We infected humanized NSG mice (huNSG: (NOD)-scid IL2R_γ^null mice engrafted with human CD34+ hematopoietic stem cells) locally with S. aureus USA300 LAC* lux into the thigh muscle in order to investigate the human immune response to acute and chronic infection. These mice proved not only to be more susceptible to MRSA infection than wild-type or “murinized” mice, but displayed furthermore inferior survival and signs of systemic infection in an otherwise localized infection model. The rate of humanization correlated directly with the severity of disease and survival of the mice. Human and murine cytokine levels in blood and at the primary site of infection were strongly elevated in huNSG mice compared to all control groups. And importantly, differences in human and murine immune cell lineages surfaced during the infection, with human monocyte and B cell numbers in blood and bone marrow being significantly reduced at the later time point of infection. Murine monocytes in contrast behaved conversely by increasing cell numbers. This study demonstrates significant differences in the in vivo behavior of human and murine cells towards S. aureus infection, which might help to sharpen the translational potential of pre-clinical models for future therapeutic approaches.

Patient Derived Ex-Vivo Cancer Models in Drug Development, Personalized Medicine, and Radiotherapy

Simple Summary

This review article highlights gaps in the current system of drug development and personalized medicine for cancer therapy. The ex vivo model system using tissue biopsy from patients will advance the development of the predictive disease specific biomarker, drug screening and assessment of treatment response on a personalized basis. Although this ex vivo system demonstrated promises, there are challenges and limitations which need to be mitigated for further advancement and better applications.

Abstract

The field of cancer research is famous for its incremental steps in improving therapy. The consistent but slow rate of improvement is greatly due to its meticulous use of consistent cancer biology models. However, as we enter an era of increasingly personalized cancer care, including chemo and radiotherapy, our cancer models must be equally able to be applied to all individuals. Patient-derived organoid (PDO) and organ-in-chip (OIC) models based on the micro-physiological bioengineered platform have already been considered key components for preclinical and translational studies. Accounting for patient variability is one of the greatest challenges in the crossover from preclinical development to clinical trials and patient derived organoids may offer a steppingstone between the two. In this review, we highlight how incorporating PDO’s and OIC’s into the development of cancer therapy promises to increase the efficiency of our therapeutics.

Patient-Derived Xenograft: A More Standard "Avatar" Model in Preclinical Studies of Gastric Cancer

Despite advances in diagnosis and treatment, gastric cancer remains the third most common cause of cancer-related death in humans. The establishment of relevant animal models of gastric cancer is critical for further research. Due to the complexity of the tumor microenvironment and the genetic heterogeneity of gastric cancer, the commonly used preclinical animal models fail to adequately represent clinically relevant models of gastric cancer. However, patient-derived models are able to replicate as much of the original inter-tumoral and intra-tumoral heterogeneity of gastric cancer as possible, reflecting the cellular interactions of the tumor microenvironment. In addition to implanting patient tissues or primary cells into immunodeficient mouse hosts for culture, the advent of alternative hosts such as humanized mouse hosts, zebrafish hosts, and in vitro culture modalities has also facilitated the advancement of gastric cancer research. This review highlights the current status, characteristics, interfering factors, and applications of patient-derived models that have emerged as more valuable preclinical tools for studying the progression and metastasis of gastric cancer.

Research Progress on Gene Editing Based on Nano-Drug Delivery Vectors for Tumor Therapy

Malignant tumors pose a serious threat to human health and have high fatality rates. Conventional clinical anti-tumor treatment is mainly based on traditional surgery, chemotherapy, radiotherapy, and interventional therapy, and even though these treatment methods are constantly updated, a satisfactory efficacy is yet to be obtained. Therefore, research on novel cancer treatments is being actively pursued. We review the classification of gene therapies of malignant tumors and their advantages, as well as the development of gene editing techniques. We further reveal the nano-drug delivery carrier effect in improving the efficiency of gene editing. Finally, we summarize the progress in recent years of gene editing techniques based on nano-drug delivery carriers in the treatment of various malignant tumors, and analyze the prospects of the technique and its restricting factors.

Use of conditional reprogramming cell, patient derived xenograft and organoid for drug screening for individualized prostate cancer therapy: Current and future perspectives (Review)

Prostate cancer mortality is ranked second among all cancer mortalities in men worldwide. There is a great need for a method of efficient drug screening for precision therapy, especially for patients with existing drug‑resistant prostate cancer. Based on the concept of bacterial cell culture and drug sensitivity testing, the traditional approach of cancer drug screening is inadequate. The current and more innovative use of cancer cell culture and in vivo tumor models in drug screening for potential individualization of anti‑cancer therapy is reviewed and discussed in the present review. An ideal screening model would have the ability to identify drug activity for the targeted cells resembling what would have occurred in the in vivo environment. Based on this principle, three available cell culture/tumor screening models for prostate cancer are reviewed and considered. The culture conditions, advantages and disadvantages for each model together with ideas to best utilize these models are discussed. The first screening model uses conditional reprogramed cells derived from patient cancer cells. Although these cells are convenient to grow and use, they are likely to have different markers and characteristics from original tumor cells and thus not likely to be informative. The second model employs patient derived xenograft (PDX) which resembles an in vivo approach, but its main disadvantages are that it cannot be easily genetically modified and it is not suitable for high‑throughput drug screening. Finally, high‑throughput screening is more feasible with tumor organoids grown from patient cancer cells. The last system still needs a large number of tumor cells. It lacks in situ blood vessels, immune cells and the extracellular matrix. Based on these current models, future establishment of an organoid data bank would allow the selection of a specific organoid resembling that of an individual's prostate cancer and used for screening of suitable anticancer drugs. This can be further confirmed using the PDX model. Thus, this combined organoid‑PDX approach is expected to be able to provide the drug sensitivity testing approach for individualization of prostate cancer therapy in the near future.

Considerations for Generating Humanized Mouse Models to Test Efficacy of Antisense Oligonucleotides

Over the last decades, animal models have become increasingly important in therapeutic drug development and assessment. The use of these models, mainly mice and rats, allow evaluating drugs in the real-organism environment and context. However, several molecular therapeutic approaches are sequence-dependent, and therefore, the humanization of such models is required to assess the efficacy. The generation of genetically modified humanized mouse models is often an expensive and laborious process that may not always recapitulate the human molecular and/or physiological phenotype. In this chapter, we summarize basic aspects to consider before designing and generating humanized models, especially when they are aimed to test antisense-based therapies.

Generation of Tumor Spheroids to Evaluate T Cell and NK Cell Cytotoxicity

Tumor cell spheroids are one of the three-dimensional (3D) culture systems that can be used to study the features of tumor cells in a more physiologic condition. Indeed, this 3D culture system has been validated in preclinical studies to select anticancer drugs. Tumor cell spheroids can be obtained through employing different procedures, and here I describe in detail how to obtain spheroids from tumor cell lines of colorectal carcinoma (CRC). I analyze the procedures employed to evaluate the phenotype and growth of tumor cells in this 3D culture system. Also, interaction with immune cells is considered. Indeed, it is relevant to define whether the antitumor effects exerted by different cytotoxic lymphocyte subsets are similar when tumor cells are used either as cells adherent to a plastic substrate or floating spheroids. To obtain optimal results in this complex system, some parameters must be considered, such as those related to poorly defined experimental variables including biological and biophysical features of tumor cell lines and the quality (purity and time to use after generation) of antitumor effector lymphocyte subsets. Also, I describe in detail the methods to generate these lymphocyte subsets and to characterize their cytotoxic potential and effectiveness in killing tumor cells. Human natural killer cells and T lymphocytes expressing the γδ T cell receptor (in particular Vδ2 T cells) are considered among the cytotoxic lymphocyte populations. Eventually, it should be possible to obtain reliable and feasible results to study the molecular mechanisms involved in recognition and killing of CRC spheroids exerted by effector lymphocytes. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Generation of tumor cell spheroids Basic Protocol 2: Evaluation of ATP content of spheroids Basic Protocol 3: Evaluation of antigen expression by cell spheroids Basic Protocol 4: Generation of effector lymphocytes Basic Protocol 5: Coculture of spheroids and lymphocytes Basic Protocol 6: Evaluation of lymphocyte cytotoxicity using crystal violet staining.

Modeling human T1D-associated autoimmune processes

BACKGROUND

Type 1 diabetes (T1D) is an autoimmune disease characterized by impaired immune tolerance to β-cell antigens and progressive destruction of insulin-producing β-cells. Animal models have provided valuable insights for understanding the etiology and pathogenesis of this disease, but they fall short of reflecting the extensive heterogeneity of the disease in humans, which is contributed by various combinations of risk gene alleles and unique environmental factors. Collectively, these factors have been used to define subgroups of patients, termed endotypes, with distinct predominating disease characteristics.

SCOPE OF REVIEW

Here, we review the gaps filled by these models in understanding the intricate involvement and regulation of the immune system in human T1D pathogenesis. We describe the various models developed so far and the scientific questions that have been addressed using them. Finally, we discuss the limitations of these models, primarily ascribed to hosting a human immune system (HIS) in a xenogeneic recipient, and what remains to be done to improve their physiological relevance.

MAJOR CONCLUSIONS

To understand the role of genetic and environmental factors or evaluate immune-modifying therapies in humans, it is critical to develop and apply models in which human cells can be manipulated and their functions studied under conditions that recapitulate as closely as possible the physiological conditions of the human body. While microphysiological systems and living tissue slices provide some of these conditions, HIS mice enable more extensive analyses using in vivo systems.

Humanized Mouse Model to Study the P2X7 Receptor in Graft-Versus-Host Disease

Humanized mouse models of graft-versus-host disease (GVHD), where human immune cells are injected into immune deficient mice, are well established and provide opportunities to investigate pathways involved in GVHD development. This chapter provides an overview of human immune cell isolation, injection of these cells into immune deficient mice, monitoring of mice for signs of GVHD, and assessment of human cell engraftment using flow cytometry. Further, this chapter focuses on the P2X7 signaling pathway involved in GVHD, and describes a strategy to block the P2X7 receptor and examine the effect of this on GVHD development.

Cytotoxic T lymphocyte antigen-4 regulates development of xenogenic graft versus host disease in mice via modulation of host immune responses induced by changes in human T cell engraftment and gene expression

Graft versus host disease (GvHD) is a major clinical problem with a significant unmet medical need. We examined the role of cytotoxic T lymphocyte antigen-4 (CTLA-4) in a xenogenic GvHD (xeno-GvHD) model induced by injection of human peripheral mononuclear cells (hPBMC) into irradiated non-obese diabetic (NOD) SCID gamma (NSG) mice. Targeting the CTLA-4 pathway by treatment with CTLA-4 immunoglobulin (Ig) prevented xeno-GvHD, while anti-CTLA-4 antibody treatment exacerbated the lethality and morbidity associated with GvHD. Xeno-GvHD is associated with infiltration of hPBMCs into the lungs, spleen, stomach, liver and colon and an increase in human proinflammatory cytokines, including interferon (IFN)-γ, tumor necrosis factor (TNF)-α and interleukin (IL)-5. Infiltration of donor cells and increases in cytokines were attenuated by treatment with CTLA-4 Ig, but remained either unaffected or enhanced by anti-CTLA-4 antibody. Further, splenic human T cell phenotyping showed that CTLA-4 Ig treatment prevented the engraftment of human CD45⁺ cells, while anti-CTLA-4 antibody enhanced donor T cell expansion, particularly CD4⁺ (CD45RO⁺ ) subsets, including T box transcription factor TBX21 (Tbet)⁺ CXCR3⁺ and CD25⁺ forkhead box protein 3 (FoxP3) cells. Comprehensive analysis of transcriptional profiling of human cells isolated from mouse spleen identified a set of 417 differentially expressed genes (DEGs) by CTLA-4 Ig treatment and 13 DEGs by anti-CTLA-4 antibody treatment. The CTLA-4 Ig regulated DEGs mapped to down-regulated apoptosis, inflammasome, T helper type 17 (Th17) and regulatory T cell (T_reg ) pathways and enhanced Toll-like receptor (TLR) receptor signaling, TNF family signaling, complement system and epigenetic and transcriptional regulation, whereas anti-CTLA-4 antibody produced minimal to no impact on these gene pathways. Our results show an important role of co-inhibitory CTLA-4 signaling in xeno-GvHD and suggest the therapeutic utility of other immune checkpoint co-inhibitory pathways in the treatment of immune-mediated diseases driven by hyperactive T cells.

New horizons in early drugs development in solid cancers

PURPOSE OF REVIEW

Drug development is the process of bringing new anticancer agents into clinical practice. From the basic research to clinical research each step is essential and intimately linked. The aim of this review is to describe emerging preclinical models and to provide an overview of selected drugs recently developed in oncology.

RECENT FINDINGS

Preclinical models reproducing human immune-tumor interactions, 3D cell cultures and microfluidic platforms are of great interest for the development of immunotherapies and combination therapies and offer the opportunity to better understand the interplay between cancer and stromal cells.Following a better biological understanding of cancer and advances in precision oncology, new exciting drugs (e.g. antibodies-drugs conjugates [ADCs], immunotherapeutic strategies, molecular-targeted therapies) have entered the field of clinical research and even clinical practice.

SUMMARY

Recent improvements in preclinical models will allow an accurate selection of drug candidates for clinical research. Innovative drugs are currently being developed from early to later phases of development. An important remaining challenge in drug development is to set up a new model of patient-centered clinical research to facilitate quick access to innovation and target-oriented trials.

Three-Dimensional Culture Models to Study Innate Anti-Tumor Immune Response: Advantages and Disadvantages

Several approaches have shown that the immune response against tumors strongly affects patients' clinical outcome. Thus, the study of anti-tumor immunity is critical to understand and potentiate the mechanisms underlying the elimination of tumor cells. Natural killer (NK) cells are members of innate immunity and represent powerful anti-tumor effectors, able to eliminate tumor cells without a previous sensitization. Thus, the study of their involvement in anti-tumor responses is critical for clinical translation. This analysis has been performed in vitro, co-incubating NK with tumor cells and quantifying the cytotoxic activity of NK cells. In vivo confirmation has been applied to overcome the limits of in vitro testing, however, the innate immunity of mice and humans is different, leading to discrepancies. Different activating receptors on NK cells and counter-ligands on tumor cells are involved in the antitumor response, and innate immunity is strictly dependent on the specific microenvironment where it takes place. Thus, three-dimensional (3D) culture systems, where NK and tumor cells can interact in a tissue-like architecture, have been created. For example, tumor cell spheroids and primary organoids derived from several tumor types, have been used so far to analyze innate immune response, replacing animal models. Herein, we briefly introduce NK cells and analyze and discuss in detail the properties of 3D tumor culture systems and their use for the study of tumor cell interactions with NK cells.

Conditional Cell Reprogramming in Modeling Digestive System Diseases

Digestive diseases have become an important source of morbidity and mortality. The considerable financial and health burdens caused by digestive diseases confirm the importance of extensive research to better understand and treat these diseases. The development of reliable preclinical models is essential for understanding the pathogenesis of digestive diseases and developing treatment and prevention methods. However, traditional established cell lines and animal models still have many limitations in the study of the digestive system. Conditional reprogramming (CR) cell culture is a newly developed primary technology that uses irradiated Swiss-3T3-J2 mouse fibroblast cells and the Rho-associated kinase (ROCK) inhibitor Y-27632 to rapidly and efficiently generate many cells from diseased and normal tissues. CR cells (CRCs) can be reprogrammed to maintain a highly proliferative state and recapitulate the histological and genomic features of the original tissue. Moreover, after removing these conditions, the phenotype was completely reversible. Therefore, CR technology may represent an ideal model to study digestive system diseases, to test drug sensitivity, to perform gene profile analysis, and to undertake xenograft research and regenerative medicine. Indeed, together with organoid cultures, CR technology has been recognized as one of the key new technologies by NIH precision oncology and also used for NCI human cancer model initiatives (HCMI) program with ATCC. In this article, we review studies that use CR technology to conduct research on diseases of the digestive system.

Laboratory Mice - A Driving Force in Immunopathology and Immunotherapy Studies of Human Multiple Myeloma

Mouse models of human cancer provide an important research tool for elucidating the natural history of neoplastic growth and developing new treatment and prevention approaches. This is particularly true for multiple myeloma (MM), a common and largely incurable neoplasm of post-germinal center, immunoglobulin-producing B lymphocytes, called plasma cells, that reside in the hematopoietic bone marrow (BM) and cause osteolytic lesions and kidney failure among other forms of end-organ damage. The most widely used mouse models used to aid drug and immunotherapy development rely on in vivo propagation of human myeloma cells in immunodeficient hosts (xenografting) or myeloma-like mouse plasma cells in immunocompetent hosts (autografting). Both strategies have made and continue to make valuable contributions to preclinical myeloma, including immune research, yet are ill-suited for studies on tumor development (oncogenesis). Genetically engineered mouse models (GEMMs), such as the widely known Vκ*MYC, may overcome this shortcoming because plasma cell tumors (PCTs) develop de novo (spontaneously) in a highly predictable fashion and accurately recapitulate many hallmarks of human myeloma. Moreover, PCTs arise in an intact organism able to mount a complete innate and adaptive immune response and tumor development reproduces the natural course of human myelomagenesis, beginning with monoclonal gammopathy of undetermined significance (MGUS), progressing to smoldering myeloma (SMM), and eventually transitioning to frank neoplasia. Here we review the utility of transplantation-based and transgenic mouse models of human MM for research on immunopathology and -therapy of plasma cell malignancies, discuss strengths and weaknesses of different experimental approaches, and outline opportunities for closing knowledge gaps, improving the outcome of patients with myeloma, and working towards a cure.

Targeting Human lncRNAs for Treating Cardiometabolic Diseases

BACKGROUND

Long non-coding RNAs (lncRNAs) have evolved as a critical regulatory mechanism for almost all biological processes. By dynamically interacting with their molecular partners, lncRNAs regulate gene activity at multiple levels ranging from transcription, pre-mRNA splicing, RNA transporting, RNA decay, and translation of mRNA.

RESULTS AND CONCLUSIONS

Dysregulation of lncRNAs has been associated with human diseases, including cancer, neurodegenerative, and cardiometabolic diseases. However, as lncRNAs are usually much less conserved than mRNAs at the sequence level, most human lncRNAs are either primate or human specific. The pathophysiological significance of human lncRNAs is still mostly unclear due to the persistent limitations in studying human-specific genes. This review will focus on recent discoveries showing human lncRNAs' roles in regulating metabolic homeostasis and the potential of targeting this unique group of genes for treatment of cardiometabolic diseases.

Translational Block in Stroke: A Constructive and "Out-of-the-Box" Reappraisal

Why can we still not translate preclinical research to clinical treatments for acute strokes? Despite > 1000 successful preclinical studies, drugs, and concepts for acute stroke, only two have reached clinical translation. This is the translational block. Yet, we continue to routinely model strokes using almost the same concepts we have used for over 30 years. Methodological improvements and criteria from the last decade have shed some light but have not solved the problem. In this conceptual analysis, we review the current status and reappraise it by thinking "out-of-the-box" and over the edges. As such, we query why other scientific fields have also faced the same translational failures, to find common denominators. In parallel, we query how migraine, multiple sclerosis, and hypothermia in hypoxic encephalopathy have achieved significant translation successes. Should we view ischemic stroke as a "chronic, relapsing, vascular" disease, then secondary prevention strategies are also a successful translation. Finally, based on the lessons learned, we propose how stroke should be modeled, and how preclinical and clinical scientists, editors, grant reviewers, and industry should reconsider their routine way of conducting research. Translational success for stroke treatments may eventually require a bold change with solutions that are outside of the box.

Colorectal Cancer and Immunity: From the Wet Lab to Individuals

Simple Summary

Tackling the current dilemma of colorectal cancer resistance to immunotherapy is puzzling and requires novel therapeutic strategies to emerge. However, characterizing the intricate interactions between cancer and immune cells remains difficult because of the complexity and heterogeneity of both compartments. Developing rationales is intellectually feasible but testing them can be experimentally challenging and requires the development of innovative procedures and protocols. In this review, we delineated useful in vitro and in vivo models used for research in the field of immunotherapy that are or could be applied to colorectal cancer management and lead to major breakthroughs in the coming years.

Abstract

Immunotherapy is a very promising field of research and application for treating cancers, in particular for those that are resistant to chemotherapeutics. Immunotherapy aims at enhancing immune cell activation to increase tumor cells recognition and killing. However, some specific cancer types, such as colorectal cancer (CRC), are less responsive than others to the current immunotherapies. Intrinsic resistance can be mediated by the development of an immuno-suppressive environment in CRC. The mutational status of cancer cells also plays a role in this process. CRC can indeed be distinguished in two main subtypes. Microsatellite instable (MSI) tumors show a hyper-mutable phenotype caused by the deficiency of the DNA mismatch repair machinery (MMR) while microsatellite stable (MSS) tumors show a comparatively more “stable” mutational phenotype. Several studies demonstrated that MSI CRC generally display good prognoses for patients and immunotherapy is considered as a therapeutic option for this type of tumors. On the contrary, MSS metastatic CRC usually presents a worse prognosis and is not responsive to immunotherapy. According to this, developing new and innovative models for studying CRC response towards immune targeted therapies has become essential in the last years. Herein, we review the in vitro and in vivo models used for research in the field of immunotherapy applied to colorectal cancer.

Animal Models of Renal Pathophysiology and Disease

Renal diseases remain devastating illnesses with unacceptably high rates of mortality and morbidity worldwide. Animal models are essential tools to better understand the pathomechanisms of kidney-related illnesses and to develop new, successful therapeutic strategies. Magnetic resonance imaging (MRI) has been actively explored in the last decades for assessing renal function, perfusion, tissue oxygenation as well as the degree of fibrosis and inflammation. This chapter aims to provide a comprehensive overview of animal models of acute and chronic kidney diseases, highlighting MRI-specific considerations, advantages, and pitfalls, and thus assisting the researcher in experiment planning.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.

Pre-clinical tumor models of primary brain tumors: Challenges and opportunities

Primary brain tumors are a heterogeneous group of malignancies that originate in cells of the central nervous system. A variety of models tractable for preclinical studies have been developed to recapitulate human brain tumors, allowing us to understand the underlying pathobiology and explore potential treatments. However, many promising therapeutic strategies identified using preclinical models have shown limited efficacy or failed at the clinical trial stage. The inability to develop therapeutic strategies that significantly improve survival rates in patients highlight the compelling need to revisit the design of currently available animal models and explore the use of new models that allow us to bridge the gap between promising preclinical findings and clinical translation. In this review, we discuss current strategies used to model glioblastoma, the most malignant brain tumor in adults and highlight the shortcomings of specific models that must be circumvented for the development of innovative therapeutic strategies.

Establishment, characterization, and cryopreservation of cell lines derived from red-rumped agouti (Dasyprocta leporina Linnaeus, 1758) - A study in a wild rodent

Somatic cells can be used for rescuing wild mammals of ecological and economic importance, such as red-rumped agouti, through their application in advanced technologies. Thus, appropriate cell isolation, culture, and storage through cryopreservation can ensure the future safe use of these cells. We aimed to establish and evaluate the effects of culture time (second, fifth, and eighth passages) and cryopreservation on the morphology, viability, metabolism, proliferative activity, reactive oxygen species (ROS) levels, mitochondrial membrane potential (ΔΨm), and apoptosis on somatic cells derived from red-rumped agouti skin. Initially, we identified six dermal fibroblast lines by morphology, immunophenotyping, and karyotyping assays. In vitro culture after the second, fifth, and eighth passages, as well as the cryopreservation conditions used did not affect the metabolism or level of apoptosis. Nevertheless, cells in the fifth passage featured a reduction in proliferative activity and an increase in ROS levels when compared to second and eighth passage cells. Moreover, cryopreservation resulted in reduced ΔΨm when compared to non-cryopreserved cells. Additionally, cryopreserved cells showed a reduction in viability immediately after thawing; nevertheless, the viability of these cells was re-established after 11 days of in vitro culture and was similar to that of non-cryopreserved cells. In conclusion, we have shown that viable fibroblasts can be obtained from red-rumped agouti skin, featuring minimal changes after eight passages in in vitro culture systems. Additionally, adjustments to the cryopreservation protocol are necessary to reduce cellular oxidative stress caused by low temperatures.

Quantitative Systems Pharmacology Modeling of PBMC-Humanized Mouse to Facilitate Preclinical Immuno-oncology Drug Development

Progress in immunotherapy has resulted in explosively increased new therapeutic interventions and they have shown promising results in the treatment of cancer. Animal testing is performed to provide preliminary efficacy and safety data for drugs under development prior to clinical trials. However, translational challenges remain for preclinical studies such as study design and the relevance of animal models to humans. Hence, only a small fraction of cancer patients showed response. The explosion of drug candidates and therapies makes preclinical assessment of every plausible option impossible, but it can be easily tested using Quantitative System Pharmacology (QSP) models. Here, we developed a QSP model for humanized mice. Tumor growth dynamics, T cell dynamics, cytokine release, immune checkpoint expression, and drug administration were modeled and calibrated using experimental data. Tumor growth inhibition data were used for model validation. Pharmacokinetics of T cell engager (TCE), tumor growth profile, T cell expansion in the blood and infiltration into tumor, T cell dissemination from primary tumor, cytokine release profile, and expression of additional PD-L1 induced by IFN-γ were modeled and calibrated using a variety of experimental data and showed good consistency. Mouse-specific response to T cell engager monotherapy also showed the key features of in vivo efficacy of TCE. This novel QSP model, designed for human peripheral blood mononuclear cells (PBMC) engrafted xenograft mice, incorporating the most critical components of the mouse model with key cancer and immune cells, can become an integral part of preclinical drug development.

Immune characterization of pre-clinical murine models of neuroblastoma

Immunotherapy offers a potentially less toxic, more tumor-specific treatment for neuroblastoma than conventional cytotoxic therapies. Accurate and reproducible immune competent preclinical models are key to understanding mechanisms of action, interactions with other therapies and mechanisms of resistance to immunotherapy. Here we characterized the tumor and splenic microenvironment of two syngeneic subcutaneous (NXS2 and 9464D), and a spontaneous transgenic (TH-MYCN) murine model of neuroblastoma, comparing histological features and immune infiltrates to previously published data on human neuroblastoma. Histological sections of frozen tissues were stained by immunohistochemistry and immunofluorescence for immune cell markers and tumor architecture. Tissues were dissociated by enzymatic digestion, stained with panels of antibodies to detect and quantify cancer cells, along with lymphocytic and myeloid infiltration by flow cytometry. Finally, we tested TH-MYCN mice as a feasible model for immunotherapy, using prior treatment with cyclophosphamide to create a therapeutic window of minimal residual disease to favor host immune development. Immune infiltration differed significantly between all the models. TH-MYCN tumors were found to resemble immune infiltration in human tumors more closely than the subcutaneous models, alongside similar GD2 and MHC class I expression. Finally, TH-MYCN transgenic mice were administered cyclophosphamide alone or in combination with an anti-GD2 or anti-4-1BB monoclonal antibody, which resulted in increase in survival in both combination therapies. The TH-MYCN transgenic mouse is a promising in vivo model for testing immunotherapy compounds and combination therapy in a preclinical setting.

Engineering a Model to Study Viral Infections: Bioprinting, Microfluidics, and Organoids to Defeat Coronavirus Disease 2019 (COVID-19)

While the number of studies related to severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) is constantly growing, it is essential to provide a framework of modeling viral infections. Therefore, this review aims to describe the background presented by earlier used models for viral studies and an approach to design an "ideal" tissue model for SARS-CoV-2 infection. Due to the previous successful achievements in antiviral research and tissue engineering, combining the emerging techniques such as bioprinting, microfluidics, and organoid formation are considered to be one of the best approaches to form in vitro tissue models. The fabrication of an integrated multi-tissue bioprinted platform tailored for SARS-CoV-2 infection can be a great breakthrough that can help defeat coronavirus disease in 2019.

Application of genome-editing systems to enhance available pig resources for agriculture and biomedicine

Traditionally, genetic engineering in the pig was a challenging task. Genetic engineering of somatic cells followed by somatic cell nuclear transfer (SCNT) could produce genetically engineered (GE) pigs carrying site-specific modifications. However, due to difficulties in engineering the genome of somatic cells and developmental defects associated with SCNT, a limited number of GE pig models were reported. Recent developments in genome-editing tools, such as zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) 9 system, have markedly changed the effort and time required to produce GE pig models. The frequency of genetic engineering in somatic cells is now practical. In addition, SCNT is no longer essential in producing GE pigs carrying site-specific modifications, because direct injection of genome-editing systems into developing embryos introduces targeted modifications. To date, the CRISPR/Cas9 system is the most convenient, cost-effective, timely and commonly used genome-editing technology. Several applicable biomedical and agricultural pig models have been generated using the CRISPR/Cas9 system. Although the efficiency of genetic engineering has been markedly enhanced with the use of genome-editing systems, improvements are still needed to optimally use the emerging technology. Current and future advances in genome-editing strategies will have a monumental effect on pig models used in agriculture and biomedicine.

Understanding Normal and Malignant Human Hematopoiesis Using Next-Generation Humanized Mice

Rodent models for human diseases contribute significantly to understanding human physiology and pathophysiology. However, given the accelerating pace of drug development, there is a crucial need for in vivo preclinical models of human biology and pathology. The humanized mouse is one tool to bridge the gap between traditional animal models and the clinic. The development of immunodeficient mouse strains with high-level engraftment of normal and diseased human immune/hematopoietic cells has made in vivo functional characterization possible. As a patient-derived xenograft (PDX) model, humanized mice functionally correlate putative mechanisms with in vivo behavior and help to reveal pathogenic mechanisms. Combined with single-cell genomics, humanized mice can facilitate functional precision medicine such as risk stratification and individually optimized therapeutic approaches.

Immunotherapies and Metastatic Cancers: Understanding Utility and Predictivity of Human Immune Cell Engrafted Mice in Preclinical Drug Development

Metastases cause high mortality in several cancers and immunotherapies are expected to be effective in the prevention and treatment of metastatic disease. However, only a minority of patients benefit from immunotherapies. This creates a need for novel therapies that are efficacious regardless of the cancer types and metastatic environments they are growing in. Preclinical immuno-oncology models for studying metastases have long been limited to syngeneic or carcinogenesis-inducible models that have murine cancer and immune cells. However, the translational power of these models has been questioned. Interactions between tumor and immune cells are often species-specific and regulated by different cytokines in mice and humans. For increased translational power, mice engrafted with functional parts of human immune system have been developed. These humanized mice are utilized to advance understanding the role of immune cells in the metastatic process, but increasingly also to study the efficacy and safety of novel immunotherapies. From these aspects, this review will discuss the role of immune cells in the metastatic process and the utility of humanized mouse models in immuno-oncology research for metastatic cancers, covering several models from the perspective of efficacy and safety of immunotherapies.

Humanized mouse model: Hematopoietic stemcell transplantation and tracking using short tandem repeat technology

Introduction

Models of mice carrying a human immune system, so‐called humanized mice, are used increasingly as preclinical models to bridge the gap between model organisms and human beings. Challenges of the humanized mouse model include finding suitable sources for human hematopoietic stem cells (HSC) and reaching sufficient engraftment of these cells in immunocompromised mice.

Methods

In this study, we compared the use of CD34⁺ HSC from cord blood (CB) vs HSC from adult mobilized peripheral blood. Furthermore, we developed a simple and highly specific test for donor identification in humanized mice by applying the detection method of short tandem repeats (STR).

Results

It was found that, in vitro, CB‐derived and adult HSC show comparable purity, viability, and differentiation potential in colony‐forming unit assays. However, in vivo, CB‐derived HSC engrafted to a significantly higher extent in NOD.Cg‐Prkdc^scidIL2rγ^tm1Wjl/SzJ (NSG) mice than adult HSC. Increasing the cell dose of adult HSC or using fresh cells without cryopreservation did not improve the engraftment rate. Interestingly, when using adult HSC, the percentage of human cells in the bone marrow was significantly higher than that in the peripheral blood. Using the STR‐based test, we were able to identify and distinguish human cells from different donors in humanized mice and in a humanized allogeneic transplantation model.

Conclusion

From these findings, we conclude that adult mobilized HSC are less suitable for generating a humanized immune system in mice than CB‐derived cells.