Humanized mice for immune system investigation: progress, promise and challenges

T cell margination: investigating the detour of T cells following forimtamig treatment in humanized mice

T cell bispecific antibodies (TCBs) are a promising new class of therapeutics for relapsed/refractory multiple myeloma. A frequently observed, yet incompletely understood effect of this treatment is the transient reduction of circulating T cell counts, also known as T cell margination (TCM). After administration of the GPRC5D-targeting TCB forimtamig (RG6234), TCM occurred in patients and correlated with cytokine release and soluble B cell maturation antigen decrease. We demonstrate that TCM is accurately represented in the humanized NSG mouse model and occurs at a lower threshold of target expression than systemic cytokine release. Application of whole-mouse tissue clearing and 3D imaging revealed that T cells accumulate in the bone marrow after treatment. We hypothesize that low amounts of targets are sufficient to rapidly redirect T cells upon TCB engagement. Therefore, we propose TCM as a beneficial, highly sensitive and early effect of forimtamig that leads T cells to likely sites of bone marrow tumor lesions.

DNA and protein-generated chimeric molecules for delivery of influenza viral epitopes in mouse and humanized NSG transfer models

Purified subunit viral antigens are weakly immunogenic and stimulate only the antibody but not the T cell-mediated immune response. An alternative approach to inducing protective immunity with small viral peptides may be the targeting of viral epitopes to immunocompetent cells by DNA and protein-engineered vaccines. This review will focus on DNA and protein-generated chimeric molecules carrying engineered fragments specific for activating cell surface co-receptors for inducing protective antiviral immunity. Adjuvanted protein-based vaccine or DNA constructs encoding simultaneously T- and B-cell peptide epitopes from influenza viral hemagglutinin, and scFvs specific for costimulatory immune cell receptors may induce a significant increase of anti-influenza antibody levels and strong CTL activity against virus-infected cells in a manner that mimics the natural infection. Here we summarize the development of several DNA and protein chimeric constructs carrying influenza virus HA317-41 fragment. The generated engineered molecules were used for immunization in intact murine and experimentally humanized NSG mouse models.

The Innate Immune System and the TRAIL-Bcl-XL Axis Mediate a Sex Bias in Lung Cancer and Confer a Therapeutic Vulnerability in Females

There is a significant sex bias in lung cancer, with males showing increased mortality compared with females. A better mechanistic understanding of these differences could help identify therapeutic targets to personalize cancer therapies to each sex. After observing a clear sex bias in humanized mice, with male patient-derived xenograft lung tumors being more progressive and deadlier than female patient-derived xenograft lung tumors, we identified mouse tumor models of lung cancer with the same sex bias. This sex bias was not observed in models of breast, colon, melanoma, and renal cancers. In vivo, the sex bias in growth and lethality required intact ovaries, functional innate NK cells and monocytes/macrophages, and the activating receptor NKG2D. Ex vivo cell culture models were sensitized to the anticancer effects of NKG2D-mediated NK cell and macrophage killing through the TRAIL-Bcl-XL axis when cultured with serum from female mice with intact ovaries. In both flank and orthotopic models, the Bcl-XL inhibitor navitoclax (ABT-263) improved tumor growth control in female mice and required NK cells, macrophages, and the TRAIL signaling pathway. This research suggests that navitoclax and TRAIL pathway agonists could be used as a personalized therapy to improve outcomes in women with lung cancer. Significance: Lung cancers in females are more susceptible to killing through a TRAIL-Bcl-XL axis, indicating that targeting this axis therapeutically could represent a personalized approach to treat female patients with lung cancer.

The translational potential of inflammation-induced skin blister human models in exploring the pathogenesis of periodontitis and its systemic health implications

Periodontitis is a highly prevalent chronic disease. Despite decades of extensive research on the topic, a complete understanding of its immunopathogenesis, especially when linked to other inflammatory comorbidities, is lacking. Ex vivo human and in vivo animal experiments have shown the host inflammatory response's crucial role in both the disease's onset and its systemic implications. These approaches, however, remain questionable when translating these findings into real-world scenarios linked to periodontitis. A clear need for new in vivo human models is discussed, especially within the context of understanding the host response to key pathogens linked to periodontitis, such as Porphyromonas gingivalis (P. gingivalis). Therefore, a skin blister model was employed to describe the stages of the host immune response in humans after challenges by microbial and/or sterile insults. A novel human challenge model using UV-killed P. gingivalis holds promise in producing new evidence and bridging the gap of the host response to periodontitis and its links with other common chronic diseases.

The use of patient-derived xenografts and patient-derived organoids in the search for new therapeutic regimens for pancreatic carcinoma. A review

Patient-derived organoids (PDOs) and xenografts (PDXs) are powerful tools for personalized medicine in pancreatic cancer (PC) research. This study explores the complementary strengths of PDOs and PDXs in terms of practicality, genetic fidelity, cost, and labor considerations. Among other models like 2D cell cultures, spheroids, cancer-on-chip systems, cell line-derived xenografts (CDX), and genetically engineered mouse models (GEMMs), PDOs and PDXs uniquely balance genetic fidelity and personalized medicine potential, offering distinct advantages over the simplicity of 2D cultures and the advanced, but often resource-intensive, GEMMs and cancer-on-chip systems. PDOs excel in high-throughput drug screening due to their ease of use, lower cost, and shorter experimental timelines. However, they lack a complete tumor microenvironment. Conversely, PDXs offer a more complex microenvironment that closely reflects patient tumors, potentially leading to more clinically relevant results. Despite limitations in size, number of specimens, and engraftment success, PDXs demonstrate significant concordance with patient responses to treatment, highlighting their value in personalized medicine. Both models exhibit significant genetic fidelity, making them suitable for drug sensitivity testing. The choice between PDOs and PDXs depends on the research focus, resource availability, and desired level of microenvironment complexity. PDOs are advantageous for high-throughput screening of a diverse array of potential therapeutic agents due to their relative ease of culture and scalability. PDXs, on the other hand, offer a more physiologically relevant model, allowing for a comprehensive evaluation of drug efficacy and mechanisms of action.

Atopic dermatitis: pathogenesis and therapeutic intervention

The skin serves as the first protective barrier for nonspecific immunity and encompasses a vast network of skin-associated immune cells. Atopic dermatitis (AD) is a prevalent inflammatory skin disease that affects individuals of all ages and races, with a complex pathogenesis intricately linked to genetic, environmental factors, skin barrier dysfunction as well as immune dysfunction. Individuals diagnosed with AD frequently exhibit genetic predispositions, characterized by mutations that impact the structural integrity of the skin barrier. This barrier dysfunction leads to the release of alarmins, activating the type 2 immune pathway and recruiting various immune cells to the skin, where they coordinate cutaneous immune responses. In this review, we summarize experimental models of AD and provide an overview of its pathogenesis and the therapeutic interventions. We focus on elucidating the intricate interplay between the immune system of the skin and the complex regulatory mechanisms, as well as commonly used treatments for AD, aiming to systematically understand the cellular and molecular crosstalk in AD-affected skin. Our overarching objective is to provide novel insights and inform potential clinical interventions to reduce the incidence and impact of AD.

Human stem cell models to unravel brain cancer

Pre-clinical animal models of human brain tumors have been invaluable tools for studying cancer pathogenesis and exploring novel treatment modalities. Such models recapitulate important aspects of the human disease such as the stem-progenitor-differentiated cell hierarchy. Although powerful, we argue that animal models are inherently limited in their ability to phenocopy certain important aspects of human brain tumor biology. We specifically highlight the inability of mouse models to generate certain forms aggressive pediatric medulloblastoma likely owing to cellular, anatomic, and genetic differences between the human and mouse brains. Additionally, we review some limitations of human brain tumor derived cell lines and outline why they are a sub-optimal system for purposes of pre-clinical modeling. Below, we present the case for human stem cell-based models of brain tumors, focusing mainly on glioblastoma and medulloblastoma. Drawing on several recently published studies, we review the exciting progress that has been made towards modeling human brain tumors using two-dimensional adherent stem cell cultures and three-dimensional organoids. We identify the important advances arrived at using these human stem cell-based models and suggest opportunities for future work in this direction. In this review article, we aim to highlight the utility and promises of human stem cell-based models of brain tumors as a complementary system to traditional transgenic animal and cell line systems.

Impact of immunosuppressive drugs on efficacy of mesenchymal stem cell therapy for suppressing renal fibrosis

Preemptive regenerative medicine using mesenchymal stem cells (MSCs) may provide a novel therapeutic approach to prevent the progression from organ damage to organ failure. Although immunosuppressive drugs are often used in patients with organ disorder, their impact on MSC therapy remains unclear. We investigated the effects of immunosuppressive drugs on the therapeutic efficacy of MSCs. We created unilateral ureteral obstruction models, as a well-established model of renal fibrosis, a preliminary stage of organ failure. Three immunosuppressive drugs (methylprednisolone, cyclosporine, and cyclophosphamide) were intraperitoneally administered 3 days after surgery, and MSCs were injected via tail vein the following day. Preadministration of methylprednisolone or cyclophosphamide interfered with MSC activation by reducing expression of interferon-gamma (IFN-γ) and high-mobility group box-1 protein, thus significantly attenuating the therapeutic efficacy of MSCs. Preadministration of cyclophosphamide downregulated the expression of stromal cell-derived factor-1/C-X-C motif ligand 12, which is a potent migration factor for MSCs, resulting in reduced MSC engraftment in the renal cortex. IFN-γ-preconditioned activated MSCs were unaffected by these drugs and maintained their beneficial therapeutic effects. Cyclosporine preadministration had no effect on the therapeutic efficacy of MSCs. Our study demonstrated that the administration of certain immunosuppressive drugs interfered with MSC activation and engraftment at the site of injury, resulting in a significant attenuation of their therapeutic efficacy. These findings provide crucial information for selecting patients suitable for MSC therapy. Use of MSCs preactivated with IFN-γ or other means is preferred for patients on methylprednisolone or cyclophosphamide.

Multi-Epitopic Peptide Vaccine Against Newcastle Disease Virus: Molecular Dynamics Simulation and Experimental Validation

BACKGROUND

Newcastle disease virus (NDV) is a highly contagious and economically devastating pathogen affecting poultry worldwide, leading to significant losses in the poultry industry. Despite existing vaccines, outbreaks continue to occur, highlighting the need for more effective vaccination strategies. Developing a multi-epitopic peptide vaccine offers a promising approach to enhance protection against NDV.

OBJECTIVES

Here, we aimed to design and evaluate a multi-epitopic vaccine against NDV using molecular dynamics (MD) simulation.

METHODOLOGY

We retrieved NDV sequences for the fusion (F) protein and hemagglutinin-neuraminidase (HN) protein. Subsequently, B-cell and T-cell epitopes were predicted. The top potential epitopes were utilized to design the vaccine construct, which was subsequently docked against chicken TLR4 and MHC1 receptors to assess the immunological response. The resulting docked complex underwent a 1 microsecond (1000 ns) MD simulation. For experimental evaluation, the vaccine's efficacy was assessed in mice and chickens using a controlled study design, where animals were randomly divided into groups receiving either a local ND vaccine or the peptide vaccine or a control treatment.

RESULTS

The 40 amino acid peptide vaccine demonstrated strong binding affinity and stability within the TLR4 and MHC1 receptor-peptide complexes. The root mean square deviation of peptide vaccine and TLR4 receptor showed rapid stabilization after an initial repositioning. The root mean square fluctuation revealed relatively low fluctuations (below 3 Å) for the TLR4 receptor, while the peptide exhibited higher fluctuations. The overall binding energy of the peptide vaccine with TLR4 and MHC1 receptors amounted to -15.7 kcal·mol-1 and -36.8 kcal·mol-1, respectively. For experimental evaluations in mice and chicken, the peptide vaccine was synthesized using services of GeneScript Biotech® (Singapore) PTE Limited. Experimental evaluations showed a significant immune response in both mice and chickens, with the vaccine eliciting robust antibody production, as evidenced by increasing HI titers over time. Statistical analysis was performed using an independent t-test with Type-II error to compare the groups, calculating the p-values to determine the significance of the immune response between different groups.

CONCLUSIONS

Multi-epitopic peptide vaccine has demonstrated a good immunological response in natural hosts.

Cutibacterium acnes invades submicron osteocyte lacuno-canalicular networks following implant-associated osteomyelitis

Cutibacterium acnes, part of normal skin flora, is increasingly recognized as an opportunistic pathogen capable of causing chronic prosthetic joint infections (PJI) associated with total hip and knee arthroplasty. However, there is a paucity of literature examining the pathogenesis of C. acnes during PJI. To study this, we developed an implant-associated osteomyelitis murine model in which 8-10-week-old C57BL6 mice were subjected to transtibial implantation of titanium or stainless-steel L-shaped pins contaminated with C. acnes. Postsurgery, mice were killed on Days 14 and 28 for terminal assessments of (1) bacterial load in bone, implant, and internal organs (heart, spleen, kidney, and liver), (2) bone osteolysis (micro-CT), (3) abscess formation (histology), and (4) systematic electron microscopy (EM). In vitro scanning EM (SEM) confirmed that C. acnes can form biofilms on stainless-steel and titanium implants. In mice, C. acnes could persist for 28 days in the tibia. Also, we observed C. acnes dissemination to internal organs. C. acnes chronic osteomyelitis revealed markedly reduced bone osteolysis and abscess formation compared to Staphylococcus aureus infections. Importantly, transmission EM (TEM) investigation revealed the presence of C. acnes within canaliculi, demonstrating that C. acnes can invade the osteocyte lacuno-canalicular networks (OLCN) within bone. Our preliminary pilot study, for the first time, revealed that the OLCN in bone can be a reservoir for C. acnes and potentially provides a novel mechanism of why C. acnes chronic implant-associated bone infections are difficult to treat.

Human GM-CSF/IL-3 enhance tumor immune infiltration in humanized HCC patient-derived xenografts

Background & Aims

Responses to immunotherapies in hepatocellular carcinoma (HCC) are suboptimal with no biomarkers to guide patient selection. "Humanized" mice represent promising models to address this deficiency but are limited by variable chimerism and underdeveloped myeloid compartments. We hypothesized that expression of human GM-CSF and IL-3 increases tumor immune cell infiltration, especially myeloid-derived cells, in humanized HCC patient-derived xenografts (PDXs).

Material and Methods

NOG (NOD/Shi- scid /IL-2R null ) and NOG-EXL (huGM-CSF/huIL-3 NOG) mice conditioned with Busulfan underwent i.v. injection of human CD34+ cells. HCC PDX tumors were then implanted subcutaneously (SQ) or orthotopically (OT). Following serial blood sampling, mice were euthanized at defined tumor sizes. Tumor, blood, liver, and spleen were analyzed by flow cytometry and immunohistochemistry.

Results

Humanized NOG-EXL mice demonstrated earlier and increased human chimerism compared to humanized NOG mice (82.1% vs 43.8%, p<0.0001) with increased proportion of human monocytes (3.2% vs 1.1%, p=0.001) and neutrophils (0.8% vs 0.3%, p=0.02) in circulation. HCC tumors in humanized NOG-EXL mice had increased human immune cell infiltration (57.6% vs 30.2%, p=0.04), noting increased regulatory T cells (14.6% vs 6.8%, p=0.04), CD4+ PD-1 expression (84.7% vs 32.0%, p<0.01), macrophages (1.2% vs 0.6%, p=0.02), and neutrophils (0.5% vs 0.1%, p<0.0001). No differences were observed in tumor engraftment or growth latency in SQ tumors, but OT tumors required implantation at two rather than four weeks post-humanization for successful engraftment. Finally, utilizing adult bone marrow instead of fetal livers enabled partial HLA-matching to HCC tumors but required more CD34+ cells.

Conclusions

Human GM-CSF and IL-3 expression in humanized mice resulted in features more closely approximating the immune microenvironment of human disease, providing a promising model for investigating critical questions in immunotherapy for HCC.

Impact and Implications

This study introduces a unique mouse model at a critical point in the evolution of treatment paradigms for patients with hepatocellular carcinoma (HCC). Immunotherapies have become first line treatment for advanced HCC; however, response rates remain low with no clear predictors of response to guide patient selection. In this context, animal models that recapitulate human disease are greatly needed. Leveraging xenograft tumors derived from patients with advanced HCCs and a commercially available immunodeficient mouse strain that expresses human GM-CSF and IL-3, we demonstrate a novel but accessible approach for modeling the HCC tumor microenvironment.

Advances in tumor stroma-based targeted delivery

The tumor stroma plays a crucial role in tumor progression, and the interactions between the extracellular matrix, tumor cells, and stromal cells collectively influence tumor progression and the efficacy of therapeutic agents. Currently, utilizing components of the tumor stroma for drug delivery is a noteworthy strategy. A number of targeted drug delivery systems designed based on tumor stromal components are entering clinical trials. Therefore, this paper provides a thorough examination of the function of tumor stroma in the advancement of targeted drug delivery systems. One approach is to use tumor stromal components for targeted drug delivery, which includes certain stromal components possessing inherent targeting capabilities like HA, laminin, along with targeting stromal cells homologously. Another method entails directly focusing on tumor stromal components to reshape the tumor stroma and facilitate drug delivery. These drug delivery systems exhibit great potential in more effective cancer therapy strategies, such as precise targeting, enhanced penetration, improved safety profile, and biocompatibility. Ultimately, the deployment of these drug delivery systems can deepen our comprehension of tumor stroma and the advanced development of corresponding drug delivery systems.

Directed evolution-based discovery of ligands for in vivo restimulation of CAR-T cells

Chimeric antigen receptor (CAR) T cell therapy targeting CD19 elicits remarkable clinical efficacy in B-cell malignancies, but many patients relapse due to failed expansion and/or progressive loss of CAR-T cells. We recently reported a strategy to potently restimulate CAR-T cells in vivo, enhancing their functionality by administration of a vaccine-like stimulus comprised of surrogate peptide ligands for a CAR linked to a lymph node-targeting amphiphilic PEG-lipid (termed CAR-T-vax). Here, we demonstrate a general strategy to generate and optimize peptide mimotopes enabling CAR-T-vax generation for any CAR. Using the clinical CD19 CAR FMC63 as a test case, we employed yeast surface display to identify peptide binders to soluble IgG versions of FMC63, which were subsequently affinity matured by directed evolution. CAR-T vaccines using these optimized mimotopes triggered marked expansion of both murine CD19 CAR-T cells in a syngeneic model and human CAR-T cells in a humanized mouse model of B cell acute lymphoblastic leukemia (B-ALL), and enhanced control of leukemia progression. This approach thus enables vaccine boosting to be applied to any clinically-relevant CAR-T cell product.

Early graft-infiltrating lymphocytes are not associated with graft rejection in a mouse model of skin transplantation

Graft-infiltrating lymphocytes (GILs) play an important role in promoting rejection after organ transplantation. We recently reported that GILs that accumulated up to 3 days post-transplantation did not promote rejection, whereas GILs present 3-5 days post-transplantation promoted rejection in a mouse heart transplantation model. However, the immunological behaviour of GILs in murine skin transplantation remains unclear. GILs were isolated on days 3, 5 or 7 post-transplantation from C57BL/6 (B6) allogeneic skin grafts transplanted onto BALB/c mice. BALB/c Rag2-/- γc-/- mice (BRGs) underwent B6 skin graft transplantation 10 weeks after adoptive transfer of day 3, 5, or 7 GILs. BRGs reconstituted with day 5 or 7 GILs completely rejected B6 grafts. However, when B6 grafts harvested from recipient BALB/c mice on day 5 or 7 were re-transplanted into BRGs, half of the re-transplanted day 5 grafts established long-term survival, although all re-transplanted day 7 grafts were rejected. BRGs reconstituted with day 3 GILs did not reject B6 grafts. Consistently, re-transplantation using day 3 skin grafts resulted in no rejection. Administration of anti-CD25 antibodies did not prevent the phenomenon observed for the day 3 skin grafts. Furthermore, BRGs reconstituted with splenocytes from naïve BALB/c mice immediately rejected the naïve B6 skin grafts and the re-transplanted day 3 B6 grafts, suggesting that day 3 GILs were unable to induce allograft rejection during the rejection process. In conclusion, the immunological role of GILs depends on the time since transplantation. Day 3 GILs had neither protective nor alloreactive effects in the skin transplant model.

Ganoderic acid T, a Ganoderma triterpenoid, modulates the tumor microenvironment and enhances the chemotherapy and immunotherapy efficacy through downregulating galectin-1 levels

Ganoderic acid T (GAT), a triterpenoid molecule of Ganoderma lucidum, exhibits anti-cancer activity; however, the underlying mechanisms remain unclear. Therefore, in this study, we aimed to investigate the anti-cancer molecular mechanisms of GAT and explore its therapeutic applications for cancer treatment. GAT exhibited potent anti-cancer activity in an ES-2 orthotopic ovarian cancer model in a humanized mouse model, leading to significant alterations in the tumor microenvironment (TME). Specifically, GAT reduced the proportion of α-SMA+ cells and enhanced the infiltration of tumor-infiltrating lymphocytes (TILs) in tumor tissues. After conducting proteomic analysis, it was revealed that GAT downregulates galectin-1 (Gal-1), a key molecule in the TME. This downregulation has been confirmed in multiple cancer cell lines and xenograft tumors. Molecular docking suggested a theoretical direct interaction between GAT and Gal-1. Further research revealed that GAT induces ubiquitination of Gal-1. Moreover, GAT significantly augmented the anti-cancer effects of paclitaxel, thereby increasing intratumoral drug concentrations and reducing tumor size. Combined with immunotherapy, GAT enhanced the tumor-suppressive effects of the anti-programmed death-ligand 1 antibody and increased the proportion of CD8+ cells in the EMT6 syngeneic mammary cancer model. In conclusion, GAT inhibited tumor growth, downregulated Gal-1, modulated the TME, and promoted chemotherapy and immunotherapy efficacy. Our findings highlight the potential of GAT as an effective therapeutic agent for cancer.

Advancing Human Vaccine Development Using Humanized Mouse Models

The development of effective vaccines against infectious diseases remains a critical challenge in global health. Animal models play a crucial role in vaccine development by providing valuable insights into the efficacy, safety, and mechanisms of immune response induction, which guide the design and formulation of vaccines. However, traditional animal models often inadequately recapitulate human immune responses. Humanized mice (hu-mice) models with a functional human immune system have emerged as invaluable tools in bridging the translational gap between preclinical research and clinical trials for human vaccine development. This review summarizes commonly used hu-mice models and advances in optimizing them to improve human immune responses. We review the application of humanized mice for human vaccine development with a focus on HIV-1 vaccines. We also discuss the remaining challenges and improvements needed for the currently available hu-mice models to better facilitate the development and testing of human vaccines for infectious diseases.

IL-15/IL-15Rα-Fc-Fusion Protein XmAb24306 Potentiates Activity of CD3 Bispecific Antibodies through Enhancing T-Cell Expansion

An insufficient quantity of functional T cells is a likely factor limiting the clinical activity of T-cell bispecific antibodies, especially in solid tumor indications. We hypothesized that XmAb24306 (efbalropendekin alfa), a lymphoproliferative interleukin (IL)-15/IL-15 receptor α (IL-15Rα) Fc-fusion protein, may potentiate the activity of T-cell dependent (TDB) antibodies. The activation of human peripheral T cells by cevostamab, an anti-FcRH5/CD3 TDB, or anti-HER2/CD3 TDB resulted in the upregulation of the IL-2/15Rβ (CD122) receptor subunit in nearly all CD8+ and majority of CD4+ T cells, suggesting that TDB treatment may sensitize T cells to IL-15. XmAb24306 enhanced T-cell bispecific antibody-induced CD8+ and CD4+ T-cell proliferation and expansion. In vitro combination of XmAb24306 with cevostamab or anti-HER2/CD3 TDB resulted in significant enhancement of tumor cell killing, which was reversed when T-cell numbers were normalized, suggesting that T-cell expansion is the main mechanism of the observed benefit. Pretreatment of immunocompetent mice with a mouse-reactive surrogate of XmAb24306 (mIL-15-Fc) resulted in a significant increase of T cells in the blood, spleen, and tumors and converted transient anti-HER2/CD3 TDB responses to complete durable responses. In summary, our results support the hypothesis that the number of tumor-infiltrating T cells is rate limiting for the activity of solid tumor-targeting TDBs. Upregulation of CD122 by TDB treatment and the observed synergy with XmAb24306 and T-cell bispecific antibodies support clinical evaluation of this novel immunotherapy combination.

Investigating the In Vivo Biodistribution of Extracellular Vesicles Isolated from Various Human Cell Sources Using Positron Emission Tomography

Positron emission tomography (PET) is a powerful tool for investigating the in vivo behavior of drug delivery systems. We aimed to assess the biodistribution of extracellular vesicles (EVs), nanosized vesicles secreted by cells isolated from various human cell sources using PET. EVs were isolated from mesenchymal stromal cells (MSCs) (MSC EVs), human macrophages (Mϕ EVs), and a melanoma cell line (A375 EVs) by centrifugation and were conjugated with deferoxamine for radiolabeling with Zr-89. PET using conjugated and radiolabeled EVs evaluated their in vivo biodistribution and tissue tropisms. Our study also investigated differences in mouse models, utilizing immunocompetent and immunocompromised mice and an A375 xenograft tumor model. Lastly, we investigated the impact of different labeling techniques on the observed EV biodistribution, including covalent surface modification and membrane incorporation. PET showed that all tested EVs exhibited extended in vivo circulation and generally low uptake in the liver, spleen, and lungs. However, Mϕ EVs showed high liver uptake, potentially attributable to the intrinsic tissue tropism of these EVs from the surface protein composition. MSC EV biodistribution differed between immunocompetent and immunodeficient mice, with increased spleen uptake observed in the latter. PET using A375 xenografts demonstrated efficient tumor uptake of EVs, but no preferential tissue-specific tropism of A375 EVs was found. Biodistribution differences between labeling techniques showed that surface-conjugated EVs had preferential blood circulation and low liver, spleen, and lung uptake compared to membrane integration. This study demonstrates the potential of EVs as effective drug carriers for various diseases, highlights the importance of selecting appropriate cell sources for EV-based drug delivery, and suggests that EV tropism can be harnessed to optimize therapeutic efficacy. Our findings indicate that the cellular source of EVs, labeling technique, and animal model can influence the observed biodistribution.

Generation of a novel immunodeficient mouse model of Mucopolysaccharidosis type IIIA to test human stem cell-based therapies

Mucopolysaccharidosis Type IIIA (MPSIIIA) is a rare inherited lysosomal storage disease caused by mutations in the SGSH gene. This genetic variation results in the deficiency of the N-sulfoglucosamine sulfohydrolase enzyme, preventing the breakdown of heparan sulfate within lysosomes. The progressive accumulation of partially degraded substrate ultimately leads to brain pathology, for which there is currently no approved treatment. An established MPSIIIA mouse model has proved to be a vital asset to test several brain-targeting strategies. Nonetheless, the assessment of human stem cell-based products, an emerging research field, necessitates the use of an immunocompromised xenogeneic disease model. In the present study, we addressed this issue by generating a highly immunodeficient mouse model of MPSIIIA (NOD/SCID/GammaC chain null-MPSIIIA) through five generations of crossing an established MPSIIIA mouse model and a NOD/SCID/GammaC chain null (NSG) mouse. The immune system composition, behavioural phenotype and histopathological hallmarks of the NSG-MPSIIIA model were then evaluated. We demonstrated that NSG-MPSIIIA mice display compromised adaptive immunity, ultimately facilitating the successful engraftment of human iPSC-derived neural progenitor cells in the brain up to three months post-delivery. Furthermore, female NSG-MPSIIIA exhibit spatial working memory deficits and hyperactive behaviour, similar to MPSIIIA mice, which usually manifest around 5 months of age. NSG-MPSIIIA mice also developed primary disease-related neuropathological features in common with the MPSIIIA model, including lysosomal enlargement with storage of excess sulphated heparan sulphate and increased gliosis in several areas of the brain. In the future, the NSG-MPSIIIA mouse model holds the potential to serve as a valuable platform for evaluating human stem-cell based therapies for MPSIIIA patients.

Competing endogenous RNAs regulatory crosstalk networks: The messages from the RNA world to signaling pathways directing cancer stem cell development

Cancer stem cells (CSCs) are one of the cell types that account for cancer heterogeneity. The cancer cells arrest in G0 and generate non-CSC progeny through self-renewal and pluripotency, resulting in tumor recurrence, metastasis, and resistance to chemotherapy. They can stimulate tumor relapse and re-grow a metastatic tumor. So, CSCs is a promising target for eradicating tumors, and developing an anti-CSCs therapy has been considered. In recent years competing endogenous RNA (ceRNA) has emerged as a significant class of post-transcriptional regulators that affect gene expression via competition for microRNA (miRNA) binding. Furthermore, aberrant ceRNA expression is associated with tumor progression. Recent findings show that ceRNA network can cause tumor progression through the effect on CSCs. To overcome therapeutic resistance due to CSCs, we need to improve our current understanding of the mechanisms by which ceRNAs are implicated in CSC-related relapse. Thus, this review was designed to discuss the role of ceRNAs in CSCs' function. Targeting ceRNAs may open the path for new cancer therapeutic targets and can be used in clinical research.

Genome-wide CRISPR screening identifies tyrosylprotein sulfotransferase-2 as a target for augmenting anti-PD1 efficacy

BACKGROUND

Immune checkpoint therapy (ICT) provides durable responses in select cancer patients, yet resistance remains a significant challenge, prompting the exploration of underlying molecular mechanisms. Tyrosylprotein sulfotransferase-2 (TPST2), known for its role in protein tyrosine O-sulfation, has been suggested to modulate the extracellular protein-protein interactions, but its specific role in cancer immunity remains largely unexplored.

METHODS

To explore tumor cell-intrinsic factors influencing anti-PD1 responsiveness, we conducted a pooled loss-of-function genetic screen in humanized mice engrafted with human immune cells. The responsiveness of cancer cells to interferon-γ (IFNγ) was estimated by evaluating IFNγ-mediated induction of target genes, STAT1 phosphorylation, HLA expression, and cell growth suppression. The sulfotyrosine-modified target gene of TPST2 was identified by co-immunoprecipitation and mass spectrometry. The in vivo effects of TPST2 inhibition were evaluated using mouse syngeneic tumor models and corroborated by bulk and single-cell RNA sequencing analyses.

RESULTS

Through in vivo genome-wide CRISPR screening, TPST2 loss-of-function emerged as a potential enhancer of anti-PD1 treatment efficacy. TPST2 suppressed IFNγ signaling by sulfating IFNγ receptor 1 at Y397 residue, while its downregulation boosted IFNγ-mediated signaling and antigen presentation. Depletion of TPST2 in cancer cells augmented anti-PD1 antibody efficacy in syngeneic mouse tumor models by enhancing tumor-infiltrating lymphocytes. RNA sequencing data revealed TPST2's inverse correlation with antigen presentation, and increased TPST2 expression is associated with poor prognosis and altered cancer immunity across cancer types.

CONCLUSIONS

We propose TPST2's novel role as a suppressor of cancer immunity and advocate for its consideration as a therapeutic target in ICT-based treatments.

Against all odds: The road to success in the development of human immune reconstitution mice

The mouse genome has a high degree of homology with the human genome, and its physiological, biochemical, and developmental regulation mechanisms are similar to those of humans; therefore, mice are widely used as experimental animals. However, it is undeniable that interspecies differences between humans and mice can lead to experimental errors. The differences in the immune system have become an important factor limiting current immunological research. The application of immunodeficient mice provides a possible solution to these problems. By transplanting human immune cells or tissues, such as peripheral blood mononuclear cells or hematopoietic stem cells, into immunodeficient mice, a human immune system can be reconstituted in the mouse body, and the engrafted immune cells can elicit human-specific immune responses. Researchers have been actively exploring the development and differentiation conditions of host recipient animals and grafts in order to achieve better immune reconstitution. Through genetic engineering methods, immunodeficient mice can be further modified to provide a favorable developmental and differentiation microenvironment for the grafts. From initially only being able to reconstruct single T lymphocyte lineages, it is now possible to reconstruct lymphoid and myeloid cells, providing important research tools for immunology-related studies. In this review, we compare the differences in immune systems of humans and mice, describe the development history of human immune reconstitution from the perspectives of immunodeficient mice and grafts, and discuss the latest advances in enhancing the efficiency of human immune cell reconstitution, aiming to provide important references for immunological related researches.

IL-4/IL-4R axis signaling drives resistance to immunotherapy by inducing the upregulation of Fcγ receptor IIB in M2 macrophages

In recent years, immunotherapy, particularly PD-1 antibodies, have significantly enhanced the outcome of gastric cancer patients. Despite these advances, some patients do not respond well to treatment, highlighting the need to understand resistance mechanisms and develop predictive markers of treatment effectiveness. This study retrospectively analyzed data from 106 patients with stage IV gastric cancer who were treated with first-line immunotherapy in combination with chemotherapy. By comparing plasma cytokine levels between patients resistant and sensitive to PD-1 antibody therapy, the researchers identified elevated IL-4 expression in the resistant patients. Mechanical investigations revealed that IL-4 induces metabolic changes in macrophages that activate the PI3K/AKT/mTOR pathway. This alteration promotes ATP production, enhances glycolysis, increases lactic acid production, and upregulates FcγRIIB expression in macrophages. Ultimately, these changes lead to CD8+ T cell dysfunction and resistance to PD-1 antibody therapy in gastric cancer. These findings highlight the role of IL-4-induced macrophage polarization and metabolic reprogramming in immune resistance and verify IL-4 as potential targets for improving treatment outcomes in gastric cancer patients.

Humanized Mouse Models of Bacterial Infections

Bacterial infections continue to represent a significant healthcare burden worldwide, causing considerable mortality and morbidity every year. The emergence of multidrug-resistant bacterial strains continues to rise, posing serious risks to controlling global disease outbreaks. To develop novel and more effective treatment and vaccination programs, there is a need for clinically relevant small animal models. Since multiple bacterial species have human-specific tropism for numerous virulence factors and toxins, conventional mouse models do not fully represent human disease. Several human disease characteristic phenotypes, such as lung granulomas in the case of Mycobacterium tuberculosis infections, are absent in standard mouse models. Alternatively, certain pathogens, such as Salmonella enterica serovar typhi and Staphylococcus aureus, can be well tolerated in mice and cleared quickly. To address this, multiple groups have developed humanized mouse models and observed enhanced susceptibility to infection and a more faithful recapitulation of human disease. In the last two decades, multiple humanized mouse models have been developed to attempt to recapitulate the human immune system in a small animal model. In this review, we first discuss the history of immunodeficient mice that has enabled the engraftment of human tissue and the engraftment methods currently used in the field. We then highlight how humanized mouse models successfully uncovered critical human immune responses to various bacterial infections, including Salmonella enterica serovar Typhi, Mycobacterium tuberculosis, and Staphylococcus aureus.

Psoriatic arthritis subtypes are phenocopied in humanized mice

Psoriatic arthritis (PsA) is a complex inflammatory disease that challenges diagnosis and complicates the rational selection of effective therapies. Although T cells are considered active effectors in psoriasis and PsA, the role of CD8+ T cells in pathogenesis is not well understood. We selected the humanized mouse model NSG-SGM3 transgenic strain to examine psoriasis and PsA endotypes. Injection of PBMCs and sera from patients with psoriasis and PsA generated parallel skin and joint phenotypes in the recipient mouse. The transfer of human circulating memory T cells was followed by migration and accumulation in the skin and synovia of these immunodeficient mice. Unexpectedly, immunoglobulins were required for recapitulation of the clinical phenotype of psoriasiform lesions and PsA domains (dactylitis, enthesitis, bone erosion). Human CD8+ T cells expressing T-bet, IL-32 and CXCL14 were detected by spatial transcriptomics in murine synovia and by immunofluorescence in the human PsA synovia. Importantly, depletion of human CD8+ T cells prevented skin and synovial inflammation in mice humanized with PsA peripheral blood cells. The humanized model of psoriasis and PsA represents a valid platform for accelerating the understanding of disease pathogenesis, improving the design of personalized therapies, and revealing psoriatic disease targets.

Polymer-drug and polymer-protein conjugated nanocarriers: Design, drug delivery, imaging, therapy, and clinical applications

Polymer-drug conjugates and polymer-protein conjugates have been pivotal in the realm of drug delivery systems for over half a century. These polymeric drugs are characterized by the conjugation of therapeutic molecules or functional moieties to polymers, enabling a range of benefits including extended circulation times, targeted delivery, controlled release, and decreased immunogenicity. This review delves into recent advancements and challenges in the clinical translations and preclinical studies of polymer-drug conjugates and polymer-protein conjugates. The design principles and functionalization strategies crucial for the development of these polymeric drugs were explored followed by the review of structural properties and characteristics of various polymer carriers. This review also identifies significant obstacles in the clinical translation of polymer-drug conjugates and provides insights into the directions for their future development. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Emerging In Vitro and In Vivo Models: Hope for the Better Understanding of Cancer Progression and Treatment

Various cancer models have been developed to aid the understanding of the underlying mechanisms of tumor development and evaluate the effectiveness of various anticancer drugs in preclinical studies. These models accurately reproduce the critical stages of tumor initiation and development to mimic the tumor microenvironment better. Using these models for target validation, tumor response evaluation, resistance modeling, and toxicity comprehension can significantly enhance the drug development process. Herein, various in vivo or animal models are presented, typically consisting of several mice and in vitro models ranging in complexity from transwell models to spheroids and CRISPR-Cas9 technologies. While in vitro models have been used for decades and dominate the early stages of drug development, they are still limited primary to simplistic tests based on testing on a single cell type cultivated in Petri dishes. Recent advancements in developing new cancer therapies necessitate the generation of complicated animal models that accurately mimic the tumor's complexity and microenvironment. Mice make effective tumor models as they are affordable, have a short reproductive cycle, exhibit rapid tumor growth, and are simple to manipulate genetically. Human cancer mouse models are crucial to understanding the neoplastic process and basic and clinical research improvements. The following review summarizes different in vitro and in vivo metastasis models, their advantages and disadvantages, and their ability to serve as a model for cancer research.

Establishment of a humanized mouse model using steady-state peripheral blood-derived hematopoietic stem and progenitor cells facilitates screening of cancer-targeted T-cell repertoires

Background

Cancer-targeted T-cell receptor T (TCR-T) cells hold promise in treating cancers such as hematological malignancies and breast cancers. However, approaches to obtain cancer-reactive TCR-T cells have been unsuccessful.

Methods

Here, we developed a novel strategy to screen for cancer-targeted TCR-T cells using a special humanized mouse model with person-specific immune fingerprints. Rare steady-state circulating hematopoietic stem and progenitor cells were expanded via three-dimensional culture of steady-state peripheral blood mononuclear cells, and then the expanded cells were applied to establish humanized mice. The human immune system was evaluated according to the kinetics of dendritic cells, monocytes, T-cell subsets, and cytokines. To fully stimulate the immune response and to obtain B-cell precursor NAML-6- and triple-negative breast cancer MDA-MB-231-targeted TCR-T cells, we used the inactivated cells above to treat humanized mice twice a day every 7 days. Then, human T cells were processed for TCR β-chain (TRB) sequencing analysis. After the repertoires had been constructed, features such as the fraction, diversity, and immune signature were investigated.

Results

The results demonstrated an increase in diversity and clonality of T cells after treatment. The preferential usage and features of TRBV, TRBJ, and the V-J combination were also changed. The stress also induced highly clonal expansion. Tumor burden and survival analysis demonstrated that stress induction could significantly inhibit the growth of subsequently transfused live tumor cells and prolong the survival of the humanized mice.

Conclusions

We constructed a personalized humanized mouse model to screen cancer-targeted TCR-T pools. Our platform provides an effective source of cancer-targeted TCR-T cells and allows for the design of patient-specific engineered T cells. It therefore has the potential to greatly benefit cancer treatment.

Orthotopic and metastatic tumour models in preclinical cancer research

Mouse models of disease play a pivotal role at all stages of cancer drug development. Cell-line derived subcutaneous tumour models are predominant in early drug discovery, but there is growing recognition of the importance of the more complex orthotopic and metastatic tumour models for understanding both target biology in the correct tissue context, and the impact of the tumour microenvironment and the immune system in responses to treatment. The aim of this review is to highlight the value that orthotopic and metastatic models bring to the study of tumour biology and drug development while pointing out those models that are most likely to be encountered in the literature. Important developments in orthotopic models, such as the increasing use of early passage patient material (PDXs, organoids) and humanised mouse models are discussed, as these approaches have the potential to increase the predictive value of preclinical studies, and ultimately improve the success rate of anticancer drugs in clinical trials.

Orthotopic model for the analysis of melanoma circulating tumor cells

Metastatic melanoma, a highly lethal form of skin cancer, presents significant clinical challenges due to limited therapeutic options and high metastatic capacity. Recent studies have demonstrated that cancer dissemination can occur earlier, before the diagnosis of the primary tumor. The progress in understanding the kinetics of cancer dissemination is limited by the lack of animal models that accurately mimic disease progression. We have established a xenograft model of human melanoma that spontaneously metastasizes to lymph nodes and lungs. This model allows precise monitoring of melanoma progression and is suitable for the quantitative and qualitative analysis of circulating tumor cells (CTCs). We have validated a flow cytometry-based protocol for CTCs enumeration and isolation. We could demonstrate that (i) CTCs were detectable in the bloodstream from the fourth week after tumor initiation, coinciding with the lymph node metastases appearance, (ii) excision of the primary tumor accelerated the formation of metastases in lymph nodes and lungs as early as one-week post-surgery, accompanied by the increased numbers of CTCs, and (iii) CTCs change their surface protein signature. In summary, we present a model of human melanoma that can be effectively utilized for future drug efficacy studies.

Carprofen Attenuates Postoperative Mechanical and Thermal Hypersensitivity after Plantar Incision in Immunodeficient NSG Mice

Immunodeficient NSG mice are reported to be less responsive to buprenorphine analgesia. Here, we used NSG mice to compare the efficacy of the commonly used dose of carprofen (5 mg/kg) with 5 and 10 times that dose (25 and 50 mg/kg) for attenuating postoperative mechanical and thermal hypersensitivity following an incisional pain model. Male and female NSG mice (n = 45) were randomly assigned to one of 4 groups and received daily subcutaneous injections for 3 d: saline (5 mL/kg), 5 mg/kg carprofen (Carp5), 25 mg/kg carprofen (Carp25), and 50 mg/kg carprofen (Carp50). Mechanical and thermal hypersensitivity were assessed 24 h before and at 4, 24, and 48 h after surgery. Plasma carprofen concentrations were measured in a separate group of mice (n = 56) on days 0 (at 2, 4, 12, and 23 h), 1, and 2 after the first, second, and third doses, respectively. Toxicity was assessed through daily fecal occult blood testing (n = 27) as well as gross and histopathologic evaluation (n = 15). Our results indicated that the saline group showed both mechanical and thermal hypersensitivity throughout the study. Carp5 did not attenuate mechanical or thermal hypersensitivity at any time point. Carp25 attenuated mechanical and thermal (except for the 4-h time point) hypersensitivity. Carp50 attenuated only thermal hypersensitivity at 24 h. Fecal occult blood was detected in 1 of 8 Carp25-treated mice at 48 and 72 h. Histopathologic abnormalities (gastric ulceration, ulcerative enteritis, and renal lesions) were observed in some Carp50-treated mice. Plasma carprofen concentrations were dose and time dependent. Our results indicate that Carp25 attenuated postoperative mechanical and thermal hypersensitivity more effectively than Carp5 or Carp50 in NSG mice with incisional pain. Therefore, we recommend providing carprofen at 25 mg/kg SID for incisional pain procedures using immunodeficient NSG mouse.

TheraVision: Engineering platform technology for the development of oncolytic viruses based on herpes simplex virus type 1

Viruses are able to efficiently penetrate cells, multiply, and eventually kill infected cells, release tumor antigens, and activate the immune system. Therefore, viruses are highly attractive novel agents for cancer therapy. Clinical trials with first generations of oncolytic viruses (OVs) are very promising but show significant need for optimization. The aim of TheraVision was to establish a broadly applicable engineering platform technology for combinatorial oncolytic virus and immunotherapy. Through genetic engineering, an attenuated herpes simplex virus type 1 (HSV1) was generated that showed increased safety compared to the wild-type strain. To demonstrate the modularity and the facilitated generation of new OVs, two transgenes encoding retargeting as well as immunomodulating single-chain variable fragments (scFvs) were integrated into the platform vector. The resulting virus selectively infected epidermal growth factor receptor (EGFR)-expressing cells and produced a functional immune checkpoint inhibitor against programmed cell death protein 1 (PD-1). Thus, both viral-mediated oncolysis and immune-cell-mediated therapy were combined into a single viral vector. Safety and functionality of the armed OVs have been shown in novel preclinical models ranging from patient-derived organoids and tissue-engineered human in vitro 3D tumor models to complex humanized mouse models. Consequently, a novel and proprietary engineering platform vector based on HSV1 is available for the facilitated preclinical development of oncolytic virotherapy.

The Effects of Busulfan on Xenogeneic Transplantation of Human Peripheral Blood Mononuclear Cells in Recipient Mice

BACKGROUND

Humanized mouse models with engraftment of human peripheral blood mononuclear cells (PBMCs) or hematopoietic stem cells (HSCs) are effective tools for the study of human immunity. Busulfan has been used as a substitute for irradiation in human hematopoietic stem cell (HSC) transplantation models, but it has not been tested in human peripheral blood mononuclear cell (PBMC) transplantation models.

METHODS

This study evaluated PBMC engraftment using cytometry and enzyme-linked immunosorbent assay (ELISA) in female NOD.CB17/Prkdcscid/JKrb/ IL2 receptor γ-/- (NIG) mice treated with busulfan.

RESULTS

In this model, the percentage of human CD3+ T cell engraftment in the blood was 28.2%, with dominant infiltration of CD8+ cells in the spleen 3 weeks post PBMC transplantation. Production of human cytokines, including Interleukin (IL)-12p70, IL-4, IL-5, IFN-γ, IL-6, IL-8, IL-22, Tumor Necrosis Factor alpha, and IL-10, was determined in mice treated with busulfan.

CONCLUSIONS

Our findings demonstrate that busulfan treatment is a beneficial alternative for simple and efficient PBMC engraftment in a rodent model, possibly helping to evaluate human immunity in preclinical studies.

The Confounding Role of Graft-Versus-Host Disease in Animal Models of Cancer Immunotherapy: A Systematic Review

BACKGROUND

Cancer immunotherapy has emerged as a transformative approach for treating various malignancies, including melanoma, lung cancer, breast cancer, and leukemia. Animal models have been instrumental in elucidating the mechanisms and potential of these therapies. However, graft-versus-host disease (GVHD) is an inherent challenge in these studies, primarily because the introduction of foreign immune cells or tissues often triggers immune responses.

METHODS

A detailed systematic search was conducted across various scientific databases, including PubMed, Scopus, Embase, and Web of Science. The search aimed to identify peer-reviewed articles published in English from January 2000 to September 2023. Keywords and phrases used in the search included "Graft-versus-Host Disease", "GVHD", "animal models", "cancer immunotherapy", and combinations thereof. Boolean operators (AND/OR) were employed to refine the search. Finally, 6 articles were included in this systematic review, which is registered on PROSPERO (ID number CRD42024488544).

RESULTS

Our systematic review identified several mechanisms employed in animal studies to mitigate the confounding effects of GVHD. These included genetically modified mouse models, immunosuppressive drugs, and humanized mice. Furthermore, the review highlights innovative approaches such as selective T-cell depletion and the use of specific cytokine inhibitors.

CONCLUSION

By systematically identifying and mitigating the confounding effects of GVHD, we can significantly improve the predictive validity of preclinical trials, obtain broadly applicable findings, improve the efficiency of drugs, enhance safety profiling, and develop better therapeutic strategies. This approach is crucial in ensuring that the immunotherapeutic strategies developed in the laboratory are reflective of the human physiological response, thereby bridging a critical translational gap in oncological research.

Recapitulating the immune system of hemophilia A patients with inhibitors using immunodeficient mice

BACKGROUND AND AIM

Treating hemophilia A patients who develop inhibitors remains a clinical challenge. A mouse model of hemophilia A can be used to test the efficacy of strategies for inhibitor suppression, but the differences in the immune systems of mice and humans limit its utility. To address this shortcoming, we established a humanized NOD/SCID-IL2rγnull hemophilia A (hu-NSG-HA) mouse model with a severely deficient mouse immune system presenting a patient's adapted immune cells.

METHODS AND RESULTS

Through intrasplenic injection with patient inhibitor-positive peripheral blood mononuclear cells (PBMCs), utilizing an adeno-associated viral delivery system expressing human BLyS, and regular FVIII challenge, human C19+ B cells were expanded in vivo to secrete anti-FVIII antibodies. Both the inhibitor and the human anti-FVIII IgG, including the predominant subclasses (IgG1 and IgG4) present in the majority of inhibitor patients, were detected in the mouse model. We further segregated and expanded the different clones of human anti-FVIII-secreting cells through subsequent transplantation of splenocytes derived from hu-NSG-HA mice into another NSG-HA mouse. By transplanting a patient's PBMCs into the NSG-HA mouse model, we demonstrated the success of reintroducing a strong anti-FVIII immune response for a short period in mice with the immune systems of inhibitor-positive patients.

CONCLUSION

Our results demonstrate a potential tool for directly obtaining functional human-derived antigen-specific antibodies and antibody-secreting cells, which may have therapeutic value for testing patient-specific immune responses to treatment options to assist in clinical decisions.

Immune-restoring CAR-T cells display antitumor activity and reverse immunosuppressive TME in a humanized ccRCC mouse model

One of the major barriers that have restricted successful use of chimeric antigen receptor (CAR) T cells in the treatment of solid tumors is an unfavorable tumor microenvironment (TME). We engineered CAR-T cells targeting carbonic anhydrase IX (CAIX) to secrete anti-PD-L1 monoclonal antibody (mAb), termed immune-restoring (IR) CAR G36-PDL1. We tested CAR-T cells in a humanized clear cell renal cell carcinoma (ccRCC) orthotopic mouse model with reconstituted human leukocyte antigen (HLA) partially matched human leukocytes derived from fetal CD34+ hematopoietic stem cells (HSCs) and bearing human ccRCC skrc-59 cells under the kidney capsule. G36-PDL1 CAR-T cells, haploidentical to the tumor cells, had a potent antitumor effect compared to those without immune-restoring effect. Analysis of the TME revealed that G36-PDL1 CAR-T cells restored active antitumor immunity by promoting tumor-killing cytotoxicity, reducing immunosuppressive cell components such as M2 macrophages and exhausted CD8+ T cells, and enhancing T follicular helper (Tfh)-B cell crosstalk.

Potential Perturbations of Critical Cancer-regulatory Genes in Triple-Negative Breast Cancer Cells Within the Humanized Microenvironment of Patient-derived Xenograft Models

PURPOSE

In this study, we aimed to establish humanized patient-derived xenograft (PDX) models for triple-negative breast cancer (TNBC) using cord blood (CB) hematopoietic stem cells (HSCs). Additionally, we attempted to characterize the immune microenvironment of the humanized PDX model to understand the potential implications of altered tumor-immune interactions in the humanized PDX model on the behavior of TNBC cells.

METHODS

To establish a humanized mouse model, high-purity CD34+ HSCs from CB were transplanted into immunodeficient NOD scid γ mice. Peripheral and intratumoral immune cell compositions of humanized and non-humanized mice were compared. Additionally, RNA sequencing of the tumor tissues was performed to characterize the gene expression features associated with humanization.

RESULTS

After transplanting the CD34+ HSCs, CD45+ human immune cells appeared within five weeks. A humanized mouse model showed viable human immune cells in the peripheral blood, lymphoid organs, and in the tumor microenvironment. Humanized TNBC PDX models showed varying rates of tumor growth compared to that of non-humanized mice. RNA sequencing of the tumor tissue showed significant alterations in tumor tissues from the humanized models. tumor necrosis factor receptor superfamily member 11B (TNFRSF11B) is a shared downregulated gene in tumor tissues from humanized models. Silencing of TNFRSF11B in TNBC cell lines significantly reduced cell proliferation, migration, and invasion in vitro. Additionally, TNFRSF11B silenced cells showed decreased tumorigenicity and metastatic capacity in vivo.

CONCLUSION

Humanized PDX models successfully recreated tumor-immune interactions in TNBC. TNFRSF11B, a commonly downregulated gene in humanized PDX models, may play a key role in tumor growth and metastasis. Differential tumor growth rates and gene expression patterns highlighted the complexities of the immune response in the tumor microenvironment of humanized PDX models.

Osteoclasts and Probiotics Mediate Significant Expansion, Functional Activation and Supercharging in NK, γδ T, and CD3+ T Cells: Use in Cancer Immunotherapy

Our previous studies have introduced osteoclasts (OCs) as major activators of NK cells. It was found that OCs exhibit the capabilities of inducing cell expansion as well as increasing the cytotoxic activity of NK cells by granule release and increasing the secretion of TNF-α and TRAIL, leading to increased lysis of tumors in short-term as well as long-term periods, respectively. OC- induced expanded NK cells were named supercharged NK cells (sNK) due to their significantly high functional activity as well as their significantly higher cell expansion rate. It is, however, unclear whether the OC-mediated effect in NK cells is specific or whether other cytotoxic immune cells can also be expanded and activated by OCs. We chose to focus on γδ T cells and pan T cells, which also include CD8+ T cells. In this paper, we report that OCs are capable of expanding and functionally activating both γδ T cells and pan T cells. Expanded γδ T and pan T cells were capable of secreting high levels of INF-γ, albeit with different dynamics to those of NK cells, and, moreover, they are unable to kill NK-specific targets. Since we used humanized-BLT (hu-BLT) mice as a model of human disease, we next determined whether NK and T cell activation through OCs is also evident in cells obtained from hu-BLT mice. Similar to humans, OCs were capable of increasing the cell expansion and secretion of IFN-γ in the culture of either NK or T cells from hu-BLT mice, providing yet further evidence that these mice are appropriate models to study human disease. Therefore, these studies indicated that CD3+ T or γδ T cells can proliferate and be supercharged by OCs similar to the NK cells; thus, they can be used individually or in combination in the cell therapy of cancers.

A Humanized Patient-Derived Xenograft Model for Pancreatic Cancer

Pancreatic cancer is associated with a high mortality rate, and there are still very few effective treatment options. Patient-derived xenografts have proven to be invaluable preclinical disease models to study cancer biology and facilitate testing of novel therapeutics. However, the severely immune-deficient mice used to generate standard models lack any functional immune system, thereby limiting their utility as a tool to investigate the tumor-immune cell interface. This chapter will outline a method for establishment of "humanized" patient-derived xenografts, which are reconstituted with human immune cells to imitate the immune-rich microenvironment of pancreatic cancer.

Patient-Derived Xenografts: Historical Evolution, Immunocompromised Host Models, and Translational Significance

Patient-derived xenografts (PDXs) represent a critical advancement in preclinical cancer research, wherein human tumor samples are implanted into animal models for evaluation of therapeutic responses. PDXs have emerged as indispensable tools in translational cancer research, facilitating investigation into tumor microenvironments and personalized medicine. This chapter elucidates the historical evolution of PDXs, from early attempts in the eighteenth century to contemporary immunocompromised host models that enhance engraftment success.

Similarities and Differences between Osteoclast-Mediated Functional Activation of NK, CD3+ T, and γδ T Cells from Humans, Humanized-BLT Mice, and WT Mice

This study is focused on assessing the activation in NK, CD3+ T, and γδ T cells when they interact with osteoclasts (OCs) and monocytes in the presence or absence of zoledronate (ZOL), both in humans and WT mice. OCs resulted in increased IFN-γ secretion in NK, CD3+ T, and γδ T cells, however, the significantly highest increase was seen when cells were co-cultured with ZOL-treated OCs. Our previous studies have demonstrated increased IFN-γ secretion in the peripheral blood-derived immune cells of bisphosphonate-related osteonecrosis of the jaw (BRONJ) mice model. This could be due to increased OCs-induced activation of immune cells with ZOL treatment. We also observed increased IFN-γ secretion in humanized-BLT (hu-BLT) mice NK cells when were co-cultured with OCs or monocytes, and higher IFN-γ secretion levels were seen in the presence of OCs or ZOL-treated OCs. In addition, similar effects on IFN-γ secretion levels of NK, CD3+ T, and γδ T cells were seen whether cells were co-cultured with allogeneic OCs or autologous OCs.

Current Insights in Murine Models for Breast Cancer: Present, Past and Future

Breast cancer is an intricate disease that is increasing at a fast pace, and numerous heterogeneities within it further make it difficult to investigate. We have always used animal models to understand cancer pathology and create an in vivo microenvironment that closely resembles human cancer. They are considered an indispensable part of any clinical investigation regarding cancer. Animal models have a high potency in identifying the relevant biomarkers and genetic pathways involved in the course of disease prognosis. Researchers have previously explored a variety of organisms, including Drosophila melanogaster, zebrafish, and guinea pigs, to analyse breast cancer, but murine models have proven the most comprehensive due to their homologous nature with human chromosomes, easy availability, simple gene editing, and high adaptability. The available models have their pros and cons, and it depends on the researcher to select the one most relevant to their research question. Chemically induced models are cost-effective and simple to create. Transplantation models such as allografts and xenografts can mimic the human breast cancer environment reliably. Genetically engineered mouse models (GEMMs) help to underpin the genetic alterations involved and test novel immunotherapies. Virus-mediated models and gene knockout models have also provided new findings regarding breast cancer progression and metastasis. These mouse models have also enabled the visualization of breast cancer metastases. It is also imperative to consider the cost-effectiveness of these models. Despite loopholes, mouse models have evolved and are required for disease analysis.

Kidney Immune Cell Characterization of Humanized Mouse Models

Experimental studies often fail to translate to clinical practice. Humanized mouse models are an important tool to close this gap. We immunophenotyped the kidneys of NOG (EXL) and NSG mouse strains engrafted with human CD34 + hematopoietic stem cells or PBMCs and compared with immune cell composition of normal human kidney. Human CD34 + hematopoietic stem cell engraftment results in steady renal immune cell populations in mouse kidney with key similarities in composition compared with human kidney. Successful translation of experimental mouse data to human diseases is limited because of biological differences and imperfect disease models. Humanized mouse models are being used to bring murine models closer to humans. However, data for application in renal immune cell-mediated diseases are rare. We therefore studied immune cell composition of three different humanized mouse kidneys and compared them with human kidney. NOG and NOGEXL mice engrafted with human CD34 + hematopoietic stem cells were compared with NSG mice engrafted with human PBMCs. Engraftment was confirmed with flow cytometry, and immune cell composition in kidney, blood, spleen, and bone marrow was analyzed in different models. The results from immunophenotyping of kidneys from different humanized mouse strains were compared with normal portions of human kidneys. We found significant engraftment of human immune cells in blood and kidney of all tested models. huNSG mice showed highest frequencies of hTCR + cells compared with huNOG and huNOGEXL in blood. huNOGEXL was found to have the highest hCD4 + frequency among all tested models. Non-T cells such as hCD20 + and hCD11c + cells were decreased in huNSG mice compared with huNOG and huNOGEXL. Compared with normal human kidney, huNOG and huNOGEXL mice showed representative immune cell composition, rather than huNSG mice. In summary, humanization results in immune cell infiltration in the kidney with variable immune cell composition of tested humanized mouse models and partially reflects normal human kidneys, suggesting potential use for translational studies.

Humanized mouse model for vaccine evaluation: an overview

Animal models are essential in medical research for testing drugs and vaccines. These models differ from humans in various respects, so their results are not directly translatable in humans. To address this issue, humanized mice engrafted with functional human cells or tissue can be helpful. We propose using humanized mice that support the engraftment of human hematopoietic stem cells (HSCs) without irradiation to evaluate vaccines that influence patient immunity. For infectious diseases, several types of antigens and adjuvants have been developed and evaluated for vaccination. Peptide vaccines are generally used for their capability to fight cancer and infectious diseases. Evaluation of adjuvants is necessary as they induce inflammation, which is effective for an enhanced immune response but causes adverse effects in some individuals. A trial can be done on humanized mice to check the immunogenicity of a particular adjuvant and peptide combination. Messenger RNA has also emerged as a potential vaccine against viruses. These vaccines need to be tested with human immune cells because they work by producing a particular peptide of the pathogen. Humanized mice with human HSCs that can produce both myeloid and lymphoid cells show a similar immune response that these vaccines will produce in a patient.

A Monocytic Barrier to the Humanization of Immunodeficient Mice

Mice with severe immunodeficiencies have become very important tools for studying foreign cells in an in vivo environment. Xenotransplants can be used to model cells from many species, although most often, mice are humanized through the transplantation of human cells or tissues to meet the needs of medical research. The development of immunodeficient mice is reviewed leading up to the current state-of-the-art strains, such as the NOD-scid-gamma (NSG) mouse. NSG mice are excellent hosts for human hematopoietic stem cell transplants or immune reconstitution through transfusion of human peripheral blood mononuclear cells. However, barriers to full hematopoietic engraftment still remain; notably, the survival of human cells in the circulation is brief, which limits overall hematological and immune reconstitution. Reports have indicated a critical role for monocytic cells - monocytes, macrophages, and dendritic cells - in the clearance of xenogeneic cells from circulation. Various aspects of the NOD genetic background that affect monocytic cell growth, maturation, and function that are favorable to human cell transplantation are discussed. Important receptors, such as SIRPα, that form a part of the innate immune system and enable the recognition and phagocytosis of foreign cells by monocytic cells are reviewed. The development of humanized mouse models has taken decades of work in creating more immunodeficient mice, genetic modification of these mice to express human genes, and refinement of transplant techniques to optimize engraftment. Future advances may focus on the monocytic cells of the host to find ways for further engraftment and survival of xenogeneic cells.

Genetic Alterations of NF-κB and Its Regulators: A Rich Platform to Advance Colorectal Cancer Diagnosis and Treatment

Colorectal cancer (CRC) is the third leading cause of cancer mortality in the United States, with an estimated 52,000 deaths in 2023. Though significant progress has been made in both diagnosis and treatment of CRC in recent years, genetic heterogeneity of CRC-the culprit for possible CRC relapse and drug resistance, is still an insurmountable challenge. Thus, developing more effective therapeutics to overcome this challenge in new CRC treatment strategies is imperative. Genetic and epigenetic changes are well recognized to be responsible for the stepwise development of CRC malignancy. In this review, we focus on detailed genetic alteration information about the nuclear factor (NF)-κB signaling, including both NF-κB family members, and their regulators, such as protein arginine methyltransferase 5 (PRMT5), and outer dynein arm docking complex subunit 2 (ODAD2, also named armadillo repeat-containing 4, ARMC4), etc., in CRC patients. Moreover, we provide deep insight into different CRC research models, with a particular focus on patient-derived xenografts (PDX) and organoid models, and their potential applications in CRC research. Genetic alterations on NF-κB signaling components are estimated to be more than 50% of the overall genetic changes identified in CRC patients collected by cBioportal for Cancer Genomics; thus, emphasizing its paramount importance in CRC progression. Consequently, various genetic alterations on NF-κB signaling may hold great promise for novel therapeutic development in CRC. Future endeavors may focus on utilizing CRC models (e.g., PDX or organoids, or isogenic human embryonic stem cell (hESC)-derived colonic cells, or human pluripotent stem cells (hPSC)-derived colonic organoids, etc.) to further uncover the underpinning mechanism of these genetic alterations in NF-κB signaling in CRC progression. Moreover, establishing platforms for drug discovery in dishes, and developing Biobanks, etc., may further pave the way for the development of innovative personalized medicine to treat CRC in the future.

Sniping Cancer Stem Cells with Nanomaterials

Cancer stem cells (CSCs) drive tumor initiation, progression, and therapeutic resistance due to their self-renewal and differentiation capabilities. Despite encouraging progress in cancer treatment, conventional approaches often fail to eliminate CSCs, necessitating the development of precise targeted strategies. Recent advances in materials science and nanotechnology have enabled promising CSC-targeted approaches, harnessing the power of tailoring nanomaterials in diverse therapeutic applications. This review provides an update on the current landscape of nanobased precision targeting approaches against CSCs. We elucidate the nuanced application of organic, inorganic, and bioinspired nanomaterials across a spectrum of therapeutic paradigms, encompassing targeted therapy, immunotherapy, and multimodal synergistic therapies. By examining the accomplishments and challenges in this potential field, we aim to inform future efforts to advance nanomaterial-based therapies toward more effective "sniping" of CSCs and tumor clearance.

EpCAM-targeting CAR-T cell immunotherapy is safe and efficacious for epithelial tumors

The efficacy of CAR-T cells for solid tumors is unsatisfactory. EpCAM is a biomarker of epithelial tumors, but the clinical feasibility of CAR-T therapy targeting EpCAM is lacking. Here, we report pre- and clinical investigations of EpCAM-CAR-T cells for solid tumors. We demonstrated that EpCAM-CAR-T cells costimulated by Dectin-1 exhibited robust antitumor activity without adverse effects in xenograft mouse models and EpCAM-humanized mice. Notably, in clinical trials for epithelial tumors (NCT02915445), 6 (50%) of the 12 enrolled patients experienced self-remitted grade 1/2 toxicities, 1 patient (8.3%) experienced reversible grade 3 leukopenia, and no higher-grade toxicity reported. Efficacy analysis determined two patients as partial response. Three patients showed >23 months of progression-free survival, among whom one patient experienced 2-year progress-free survival with detectable CAR-T cells 200 days after infusion. These data demonstrate the feasibility and tolerability of EpCAM-CAR-T therapy.

Patient Characteristics Associated with Growth of Patient-Derived Tumor Implants in Mice (Patient-Derived Xenografts)

Background: patient-derived xenografts (PDXs) have defined the field of translational cancer research in recent years, becoming one of the most-used tools in early drug development. The process of establishing cancer models in mice has turned out to be challenging, since little research focuses on evaluating which factors impact engraftment success. We sought to determine the clinical, pathological, or molecular factors which may predict better engraftment rates in PDXs. Methods: between March 2017 and January 2021, tumor samples obtained from patients with primary or metastatic cancer were implanted into athymic nude mice. A full comprehensive evaluation of baseline factors associated with the patients and patients' tumors was performed, with the goal of potentially identifying predictive markers of engraftment. We focused on clinical (patient factors) pathological (patients' tumor samples) and molecular (patients' tumor samples) characteristics, analyzed either by immunohistochemistry (IHC) or next-generation sequencing (NGS), which were associated with the likelihood of final engraftment, as well as with tumor growth rates in xenografts. Results: a total of 585 tumor samples were collected and implanted. Twenty-one failed to engraft, due to lack of malignant cells. Of 564 tumor-positive samples, 187 (33.2%) grew at time of analysis. The study was able to find correlation and predictive value for engraftment for the following: the use of systemic antibiotics by the patient within 2 weeks of sampling (38.1% (72/189) antibiotics- group vs. 30.7% (115/375) no-antibiotics) (p = 0.048), and the administration of systemic steroids to the patients within 2 weeks of sampling (41.5% (34/48) steroids vs. 31.7% (153/329), no-steroids) (p = 0.049). Regarding patient's baseline tests, we found certain markers could help predict final engraftment success: for lactate dehydrogenase (LDH) levels, 34.1% (140/411) of tumors derived from patients with baseline blood LDH levels above the upper limit of normality (ULN) achieved growth, against 30.7% (47/153) with normal LDH (p = 0.047). Histological tumor characteristics, such as grade of differentiation, were also correlated. Grade 1: 25.4% (47/187), grade 2: 34.8% (65/187) and grade 3: 40.1% (75/187) tumors achieved successful growth (p = 0.043), suggesting the higher the grade, the higher the likelihood of success. Similarly, higher ki67 levels were also correlated with better engraftment rates: low (Ki67 < 15%): 8.9% (9/45) achieved growth vs. high (Ki67 ≥ 15%): 31% (35/113) (p: 0.002). Other markers of aggressiveness such as the presence of lymphovascular invasion in tumor sample of origin was also predictive: 42.2% (97/230) with lymphovascular vs. 26.9% (90/334) of samples with no invasion (p = 0.0001). From the molecular standpoint, mismatch-repair-deficient (MMRd) tumors showed better engraftment rates: 62.1% (18/29) achieved growth vs. 40.8% (75/184) of proficient tumors (p = 0.026). A total of 84 PDX were breast models, among which 57.9% (11/19) ER-negative models grew, vs. 15.4% (10/65) of ER-positive models (p = 0.0001), also consonant with ER-negative tumors being more aggressive. BRAFmut cancers are more likely to achieve engraftment during the development of PDX models. Lastly, tumor growth rates during first passages can help establish a cutoff point for the decision-making process during PDX development, since the higher the tumor grades, the higher the likelihood of success. Conclusions: tumors with higher grade and Ki67 protein expression, lymphovascular and/or perineural invasion, with dMMR and are negative for ER expression have a higher probability of achieving growth in the process of PDX development. The use of steroids and/or antibiotics in the patient prior to sampling can also impact the likelihood of success in PDX development. Lastly, establishing a cutoff point for tumor growth rates could guide the decision-making process during PDX development.

CD46-ADC Reduces the Engraftment of Multiple Myeloma Patient-Derived Xenografts

An antibody-drug conjugate (ADC) targeting CD46 conjugated to monomethyl auristatin has a potent anti-myeloma effect in cell lines in vitro and in vivo, and patient samples treated ex vivo. Here, we tested if CD46-ADC may have the potential to target MM-initiating cells (MM-ICs). CD46 expression was measured on primary MM cells with a stem-like phenotype. A patient-derived xenograft (PDX) model was implemented utilizing implanted fetal bone fragments to provide a humanized microenvironment. Engraftment was monitored via serum human light chain ELISA, and at sacrifice via bone marrow and bone fragment flow cytometry. We then tested MM regeneration in PDX by treating mice with CD46-ADC or the nonbinding control-ADC. MM progenitor cells from patients that exhibit high aldehyde dehydrogenase activity also have a high expression of CD46. In PDX, newly diagnosed MM patient samples engrafted significantly more compared to relapsed/refractory samples. In mice transplanted with newly diagnosed samples, CD46-ADC treatment showed significantly decreased engraftment compared to control-ADC treatment. Our data further support the targeting of CD46 in MM. To our knowledge, this is the first study to show preclinical drug efficacy in a PDX model of MM. This is an important area for future study, as patient samples but not cell lines accurately represent intratumoral heterogeneity.