An Improved Method to Produce Clinical-Scale Natural Killer Cells from Human Pluripotent Stem Cells

Robust differentiation of NK cells from MSLN.CAR-IL-15-engineered human iPSCs with enhanced antitumor efficacy against solid tumors

Human induced pluripotent stem cells (iPSCs) offer a promising source for chimeric antigen receptor (CAR)-engineered natural killer (NK) products. However, complex iPSC-NK (iNK) manufacturing challenges clinical use. Here, we identified LiPSC-GR1.1 as a superior iPSC line for iNK production. By engineering LiPSC-GR1.1 with a mesothelin (MSLN)-targeting CAR and interleukin-15 (IL-15), we achieved robust differentiation of iPSCs into mature activated iNK cells with enhanced tumor killing efficacy, superior tumor homing, and vigorous proliferation. Single-cell transcriptomic analysis revealed that transforming growth factor-β (TGF-β)-producing tumor cells up-regulated major histocompatibility complex molecules and down-regulated MSLN post-CAR-IL-15 iNK treatment. Tumor-infiltrating CAR-IL-15 iNK cells exhibited high levels of CAR, IL-15, and NK-activating receptors, negligible checkpoint exhaustion markers, and extremely low levels of NK suppressive factors CISH, TGFBR2, and BATF, enabling them to sustain activation, metabolic fitness, and effective tumor killing within TGF-β-rich hypoxic tumor microenvironment. Overall, we developed MSLN.CAR-IL-15-engineered GR1.1-iNK therapy with enhanced antitumor efficacy for solid tumor treatment.

Feeder-cell-free system for ex vivo production of natural killer cells from cord blood hematopoietic stem and progenitor cells

Introduction

Natural Killer (NK) cells hold significant promise as therapeutic agents in immuno-oncology due to their ability to target and eliminate cancerous and infected cells without causing graft-versus-host disease or cytokine release syndrome. However, the limited availability of robust, scalable methods for generating clinical-grade NK cells remains a limiting factor to broader clinical application.

Methods

Here we report the development of a novel feeder-cell-free culture system optimized for producing NK cells from cord blood-derived CD34+ hematopoietic stem and progenitor cells (HSPCs). Our method eliminates the need for feeder cells while achieving high yields of NK cells that exhibit unique marker expression and cytotoxic functions. Cord blood CD34+ HSPCs were cultured in our established hDLL 4 culture system and generated large numbers of human T lymphoid progenitors (ProTcells) in 7 days. ProTcells were further cultured in a hDLL4-free, feeder-cell-free system for NK cell differentiation and supplemented with cytokines. Following a 7- or 14-day culture, this method produced highly pure NK cell populations (>90% CD3-CD56+).

Results

Flow and mass cytometric analysis confirmed the expression of activating receptors, transcription factors (ID2, T-bet) and cytotoxic molecules (perforin, granzyme A/B), all essential for ProT-NK cell functionality. These cells are in an immature state, indicated by the absence of maturation markers (CD16, KIRs). Functional assays demonstrated that these ProT-NK cells are capable of degranulation and cytokines production (TNFα) upon stimulation with K562 target cells and showed cytotoxicity against K562 cells superior to that of Peripheral Blood (PB)-NK. In NSG-Tg(hIL-15) mice, ProT-NK cells colonize bone marrow, the liver, and the spleen and persist and mature in bone marrow for at least 9 days post-injection. Compared to ProT-NK D21, ProT-NK D14 was superior in functional and homing potential. In vivo, an anti-tumor assay that uses a subcutaneous K562 model has demonstrated the anti-tumor potential of ProT-NK cells.

Discussion

Our ex vivo culture process supports scalable ProT-NK cell production in high yields, reducing dependency on feeder cells and mitigating contamination risks. Our findings demonstrate the feasibility of generating large, functional NK cell populations from HSPCs isolated from readily available cord blood sources and offer an efficient alternative to PB-NK cell therapies.

Novel gene manipulation approaches to unlock the existing bottlenecks of CAR-NK cell therapy

Currently, CAR-T cell therapy is known as an efficacious treatment for patients with relapsed/refractory hematologic malignancies. Nonetheless, this method faces several bottlenecks, including low efficacy for solid tumors, lethal adverse effects, high cost of autologous products, and the risk of GvHD in allogeneic settings. As a potential alternative, CAR-NK cell therapy can overcome most of the limitations of CAR-T cell therapy and provide an off-the-shelf, safer, and more affordable product. Although published results from preclinical and clinical studies with CAR-NK cells are promising, several bottlenecks must be unlocked to maximize the effectiveness of CAR-NK cell therapy. These bottlenecks include low in vivo persistence, low trafficking into tumor sites, modest efficacy in solid tumors, and sensitivity to immunosuppressive tumor microenvironment. In recent years, advances in gene manipulation tools and strategies have laid the groundwork to overcome the current bottlenecks of CAR-NK cell therapy. This review will introduce the existing gene manipulation tools and discuss their advantages and disadvantages. We will also explore how these tools can enhance CAR-NK cell therapy's safety and efficacy.

Differentiating Induced Pluripotent Stem Cells into Natural Killer Cells for Adoptive Cell Immunotherapies-Comparative Characterization of Current Protocols

Cancers constitute a leading cause of mortality. Chimeric antigen receptor (CAR) cell therapies provide breakthrough solutions for various cancers while posing considerable risks of immunological side reactions. Of various cytotoxic lymphocyte subsets, natural killer (NK) cells are considered the least immunogenic. Obtaining viable NK cells with stable phenotypes in quantities sufficient for modification is technologically challenging. The candidate sources include primary mononuclear cell cultures and immortalized NK cell lines; alternatively, the clinical-grade NK cells can be differentiated from induced pluripotent stem cells (iPSCs) by a good manufacturing practice (GMP)-compatible xeno-free protocol. In this review, we analyze existing protocols for targeted differentiation of human iPSCs into NK cells with a focus on xeno-free requirements.

CD70-targeted iPSC-derived CAR-NK cells display potent function against tumors and alloreactive T cells

Clinical application of autologous chimeric antigen receptor (CAR)-T cells is complicated by limited targeting of cancer types, as well as the time-consuming and costly manufacturing process. We develop CD70-targeted, induced pluripotent stem cell-derived CAR-natural killer (NK) (70CAR-iNK) cells as an approach for universal immune cell therapy. Besides the CD70-targeted CAR molecule, 70CAR-iNK cells are modified with CD70 gene knockout, a high-affinity non-cleavable CD16 (hnCD16), and an interleukin (IL)-15 receptor α/IL-15 fusion protein (IL15RF). Multi-gene-edited 70CAR-iNK cells exhibit robust cytotoxicity against a wide range of tumors. In vivo xenograft models further demonstrate their potency in effectively targeting lymphoma and renal cancers. Furthermore, we find that recipient alloreactive T cells express high levels of CD70 and can be eliminated by 70CAR-iNK cells, leading to improved survival and persistence of iNK cells. With the capability of tumor targeting and the potential to eliminate alloreactive T cells, 70CAR-iNK cells are potent candidates for next-generation universal immune cell therapy.

Engineered Cellular Therapies for the Treatment of Thoracic Cancers

Thoracic malignancies (lung cancers and malignant pleural mesothelioma) are prevalent worldwide and are associated with high morbidity and mortality. Effective treatments are needed for patients with advanced disease. Cell therapies are a promising approach to the treatment of advanced cancers that make use of immune effector cells that have the ability to mediate antitumor immune responses. In this review, we discuss the prospect of chimeric antigen receptor-T (CAR-T) cells, natural killer (NK) cells, T cell receptor-engineered (TCR-T) cells, and tumor-infiltrating lymphocytes (TILs) as treatments for thoracic malignancies. CAR-T cells and TILs have proven successful in several hematologic cancers and advanced melanoma, respectively, but outside of melanoma, results have thus far been unsuccessful in most other solid tumors. NK cells and TCR-T cells are additional cell therapy platforms with their own unique advantages and challenges. Obstacles that must be overcome to develop effective cell therapy for these malignancies include selecting an appropriate target antigen, combating immunosuppressive cells and signaling molecules present in the tumor microenvironment, persistence, and delivering a sufficient quantity of antitumor immune cells to the tumor. Induced pluripotent stem cells (iPSCs) offer great promise as a source for both NK and T cell-based therapies due to their unlimited expansion potential. Here, we review clinical trial data, as well as recent basic scientific advances that offer insight into how we may overcome these obstacles, and provide an overview of ongoing trials testing novel strategies to overcome these obstacles.

Advances in Induced Pluripotent Stem Cell-Derived Natural Killer Cell Therapy

Natural killer (NK) cells are cytotoxic lymphocytes of the innate immune system capable of killing virus-infected cells and/or cancer cells. The commonly used NK cells for therapeutic applications include primary NK cells and immortalized NK cell lines. However, primary NK cell therapy faces limitations due to its restricted proliferation capacity and challenges in stable storage. Meanwhile, the immortalized NK-92 cell line requires irradiation prior to infusion, which reduces its cytotoxic activity, providing a ready-made alternative and overcoming these bottlenecks. Recent improvements in differentiation protocols for iPSC-derived NK cells have facilitated the clinical production of iPSC-NK cells. Moreover, iPSC-NK cells can be genetically modified to enhance tumor targeting and improve the expansion and persistence of iPSC-NK cells, thereby achieving more robust antitumor efficacy. This paper focuses on the differentiation-protocols efforts of iPSC-derived NK cells and the latest progress in iPSC-NK cell therapy. Additionally, we discuss the current challenges faced by iPSC-NK cells and provide an outlook on future applications and developments.

Developing enhanced immunotherapy using NKG2A knockout human pluripotent stem cell-derived NK cells

Cancer immunotherapy is gaining increasing attention. However, immune checkpoints are exploited by cancer cells to evade anti-tumor immunotherapy. Here, we knocked out NKG2A, an immune checkpoint expressed on natural killer (NK) cells, in human pluripotent stem cells (hPSCs) and differentiated these hPSCs into NK (PSC-NK) cells. We show that NKG2A knockout (KO) enhances the anti-tumor and anti-viral capabilities of PSC-NK cells. NKG2A KO endows PSC-NK cells with higher cytotoxicity against HLA-E-expressing glioblastoma (GBM) cells, leukemia cells, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected cells in vitro. The NKG2A KO PSC-NK cells also exerted potent anti-tumor activity in vivo, leading to substantially suppressed tumor progression and prolonged survival of tumor-bearing mice in a xenograft GBM mouse model. These findings underscore the potential of PSC-NK cells with immune checkpoint KO as a promising cell-based immunotherapy. The unlimited supply and ease of genetic engineering of hPSCs makes genetically engineered PSC-NK an attractive option for easily accessible "off-the-shelf" cancer immunotherapy.

Phenotypic and transcriptomic profiling of induced pluripotent stem cell (iPSC)-derived NK cells and their cytotoxicity against cancers

BACKGROUND

Adoptive immunotherapy using natural killer (NK) cells has attracted considerable interest in numerous clinical trials targeting both hematological and solid tumors. Traditionally, NK cells are primarily derived from either peripheral blood (PB) or umbilical cord blood (UCB). However, these methods can lead to variability and heterogeneity within the NK cell population. In contrast, induced pluripotent stem cell (iPSC)-derived NK (iNK) cells provide a more controlled and uniform cellular population, suitable for large-scale clinical applications. This makes iNK cells a promising option for developing "off-the-shelf" immunotherapeutic products. Nevertheless, current NK cell differentiation protocols, which rely on embryoid body (EB) cultures, are labor-intensive and susceptible to unwanted heterogeneity during differentiation. Here, we developed a more efficient approach for generating iNK cells by employing a monolayer and feeder-free differentiation protocol, alongside optimized culture media.

METHODS

The iNK cells were generated using a two-step in vitro monolayer feeder-free system following NK cell development. To evaluate their maturity, phenotypic analysis was performed using flow cytometry, comparing with PB-NK cells and the NK-92 cell line. Additionally, single-cell RNA sequencing was performed to examine their transcriptomic profiles. The cytotoxic activity of the iNK cells was evaluated by co-culturing with cholangiocarcinoma (CCA) and breast cancer (BCA) cell lines in both monolayer (2D) and tumor spheroid (3D) co-culture systems.

RESULTS

We successfully differentiated iPSCs into mesoderm (ME), hematopoietic stem/progenitor cells (HSPCs), and NK cells. The resulting iNK cells exhibited typical NK cell markers such as CD45, CD56, and CD16, and expressed key functional proteins, including both activating and inhibitory receptors. Single-cell RNA sequencing confirmed that the transcriptomic profile of our iNK cells closely resembles that of PB-NK cells. Importantly, our iNK cells demonstrated strong cytotoxic abilities against various CCA and BCA cell lines, surpassing the NK-92 cell line in both monolayer cultures and tumor spheroid cultures.

CONCLUSION

This study highlights the potential of iPSCs as an effective alternative cell source for generating NK cells. Using a two-step in vitro monolayer feeder-free system, we successfully generated iNK cells that not only expressed key NK cell markers and their receptors but also displayed a transcriptomic profile closely resembling PB-NK cells. Furthermore, iNK cells exhibited cytotoxicity against CCA and BCA cell lines comparable to that of PB-NK cells. This approach could pave the way for off-the-shelf NK cell products, potentially enhancing the effectiveness of adoptive NK cell therapy.

A scalable, spin-free approach to generate enhanced induced pluripotent stem cell-derived natural killer cells for cancer immunotherapy

Natural killer (NK) cells play a vital role in innate immunity and show great promise in cancer immunotherapy. Traditional sources of NK cells, such as the peripheral blood, are limited by availability and donor variability. In addition, in vitro expansion can lead to functional exhaustion and gene editing challenges. This study aimed to harness induced pluripotent stem cell (iPSC) technology to provide a consistent and scalable source of NK cells, overcoming the limitations of traditional sources and enhancing the potential for cancer immunotherapy applications. We developed human placental-derived iPSC lines using reprogramming techniques. Subsequently, an optimized two-step differentiation protocol was introduced to generate high-purity NK cells. Initially, iPSCs were differentiated into hematopoietic-like stem cells using spin-free embryoid bodies (EBs). Subsequently, the EBs were transferred to ultra-low attachment plates to induce NK cell differentiation. iPSC-derived NK (iNK) cells expressed common NK cell markers (NKp46, NKp30, NKp44, CD16 and eomesodermin) at both RNA and protein levels. iNK cells demonstrated significant resilience to cryopreservation and exhibited enhanced cytotoxicity. The incorporation of a chimeric antigen receptor (CAR) construct further augmented their cytotoxic potential. This study exemplifies the feasibility of generating iNK cells with high purity and enhanced functional capabilities, their improved resilience to cryopreservation and the potential to have augmented cytotoxicity through CAR expression. Our findings offer a promising pathway for the development of potential cellular immunotherapies, highlighting the critical role of iPSC technology in overcoming challenges associated with traditional NK cell sources.

Revolutionizing the treatment for nasopharyngeal cancer: the impact, challenges and strategies of stem cell and genetically engineered cell therapies

Nasopharyngeal carcinoma (NPC) is a distinct malignancy of the nasopharynx and is consistently associated with the Epstein-Barr virus (EBV) infection. Its unique anatomical location and complex aetiology often result in advanced-stage disease at first diagnosis. While radiotherapy (RT) and chemotherapy have been the mainstays of treatment, they often fail to prevent tumour recurrence and metastasis, leading to high rates of treatment failure and mortality. Recent advancement in cell-based therapies, such as chimeric antigen receptor (CAR)-T cell therapy, have shown great promise in hematological malignancies and are now being investigated for NPC. However, challenges such as targeting specific tumour antigens, limited T cell persistence and proliferation, and managing treatment-related toxicities must be addressed. Extensive research is needed to enhance the effectiveness and safety of these therapies, paving the way for their integration into standard clinical practice for better management of NPC and a better quality of life for human health.

Comparative analysis of iPSC-derived NK cells from two differentiation strategies reveals distinct signatures and cytotoxic activities

Purpose

The ability to generate natural killer (NK) cells from induced pluripotent stem cells (iPSCs) has given rise to new possibilities for the large-scale production of homogeneous immunotherapeutic cellular products and opened new avenues towards the creation of "off-the-shelf" cancer immunotherapies. However, the differentiation of NK cells from iPSCs remains poorly understood, particularly regarding the ontogenic landscape of iPSC-derived NK (iNK) cells produced in vitro and the influence that the differentiation strategy employed may have on the iNK profile.

Methods

To investigate this question, we conducted a comparative analysis of two sets of iNK cells generated from the same iPSC line using two different protocols: (i) a short-term, clinically compatible feeder-free protocol corresponding to primitive hematopoiesis, and (ii) a lymphoid-based protocol representing the definitive hematopoietic step.

Results and discussion

Our work demonstrated that both protocols are capable of producing functional iNK cells. However, the two sets of resulting iNKs exhibited distinct phenotypes and transcriptomic profiles. The lymphoid-based differentiation approach generated iNKs with a more mature and activated profile, which demonstrated higher cytotoxicity against cancer cell lines compared to iNK cells produced under short-term feeder-free conditions suggesting that the differentiation strategy must be considered when designing iNK cell-based adoptive immunotherapies.

Processing human colon cancer specimens for in vitro cytotoxicity assays

Colorectal cancer (CRC) research demands reliable experimental models to enhance translational potential. Immortalized cancer cell lines, although commonly employed, exhibit limitations such as phenotypic divergence from primary tumors, which underscores the need for more representative models. This method chapter presents a protocol for collecting and processing primary CRC specimens for in vitro assays to assess the cytotoxic potential of antitumor agents, with a focus on adoptive cellular therapies. The protocol emphasizes the importance of immediate processing to minimize ex vivo alterations and includes guidelines for cryopreservation, thawing, enzymatic digestion, and mechanical disruption, which were optimized for increased cell yield and viability. An optional step of immune cell depletion is included to avoid indirect effects of endogenous leukocytes, with the option to retain this fraction for further analysis. Finally, the steps for flow cytometry-based evaluation of tumor cell apoptosis by assessment of Caspase 3/7 staining are detailed. The implementation of this standardized protocol using patient-derived specimens offers a superior alternative to immortalized cell lines for assessing therapeutic efficacy, increasing the probability of translation of preclinical research findings, and bolstering the development of innovative therapeutic strategies for CRC.

GMP-compliant iPS cell lines show widespread plasticity in a new set of differentiation workflows for cell replacement and cancer immunotherapy

Cell therapeutic applications based on induced pluripotent stem cells (iPSCs) appear highly promising and challenging at the same time. Good manufacturing practice (GMP) regulations impose necessary yet demanding requirements for quality and consistency when manufacturing iPSCs and their differentiated progeny. Given the scarcity of accessible GMP iPSC lines, we have established a corresponding production workflow to generate the first set of compliant cell banks. Hence, these lines met a comprehensive set of release specifications and, for instance, displayed a low overall mutation load reflecting their neonatal origin, cord blood. Based on these iPSC lines, we have furthermore developed a set of GMP-compatible workflows enabling improved gene targeting at strongly enhanced efficiencies and directed differentiation into critical cell types: A new protocol for the generation of retinal pigment epithelium (RPE) features a high degree of simplicity and efficiency. Mesenchymal stromal cells (MSCs) derived from iPSCs displayed outstanding expansion capacity. A fully optimized cardiomyocyte differentiation protocol was characterized by a particularly high batch-to-batch consistency at purities above 95%. Finally, we introduce a universal immune cell induction platform that converts iPSCs into multipotent precursor cells. These hematopoietic precursors could selectively be stimulated to become macrophages, T cells, or natural killer (NK) cells. A switch in culture conditions upon NK-cell differentiation induced a several thousand-fold expansion, which opens up perspectives for upscaling this key cell type in a feeder cell-independent approach. Taken together, these cell lines and improved manipulation platforms will have broad utility in cell therapy as well as in basic research.

Generation of immune cells from induced pluripotent stem cells (iPSCs): Their potential for adoptive cell therapy

Advances in human stem cell technologies enable induced pluripotent stem cells (iPSCs) to be explored as potent candidates for treating various diseases, such as malignancies, autoimmunity, immunodeficiencies, and allergic reactions. iPSCs with infinite self-renewal ability can be derived from different types of somatic cells without the ethical issues associated with embryonic stem cells. To date, numerous cell types, including various immune cell subsets [CD4+ and CD8+ T cells, gamma delta T (γδ T) cells, regulatory T cells, dendritic cells, natural killer cells, macrophages, and neutrophils] have successfully been generated from iPSCs paving the way for effective adoptive cell transfer therapy, drug development, and disease modeling. Herein, we review various iPSC-derived immune cells and their possible application in immunotherapy.

Unlocking the potential of iPSC-derived immune cells: engineering iNK and iT cells for cutting-edge immunotherapy

Induced pluripotent stem cells (iPSCs) have emerged as a revolutionary tool in cell therapies due to their ability to differentiate into various cell types, unlimited supply, and potential as off-the-shelf cell products. New advances in iPSC-derived immune cells have generated potent iNK and iT cells which showed robust killing of cancer cells in animal models and clinical trials. With the advent of advanced genome editing technologies that enable the development of highly engineered cells, here we outline 12 strategies to engineer iPSCs to overcome limitations and challenges of current cell-based immunotherapies, including safety switches, stealth edits, avoiding graft-versus-host disease (GvHD), targeting, reduced lymphodepletion, efficient differentiation, increased in vivo persistence, stemness, metabolic fitness, homing/trafficking, and overcoming suppressive tumor microenvironment and stromal cell barrier. With the development of advanced genome editing techniques, it is now possible to insert large DNA sequences into precise genomic locations without the need for DNA double strand breaks, enabling the potential for multiplexed knock out and insertion. These technological breakthroughs have made it possible to engineer complex cell therapy products at unprecedented speed and efficiency. The combination of iPSC derived iNK, iT and advanced gene editing techniques provides new opportunities and could lead to a new era for next generation of cell immunotherapies.

Strong capacity of differentiated PD-L1 CAR-modified UCB-CD34+ cells and PD-L1 CAR-modified UCB-CD34+-derived NK cells in killing target cells and restoration of the anti-tumor function of PD-1-high exhausted T Cells

BACKGROUND

Using natural killer (NK) cells to treat hematopoietic and solid tumors has great promise. Despite their availability from peripheral blood and cord blood, stem cell-derived NK cells provide an "off-the-shelf" solution.

METHODS

In this study, we developed two CAR-NK cells targeting PD-L1 derived from lentiviral transduction of human umbilical cord blood (UCB)-CD34+ cells and UCB-CD34+-derived NK cells. The transduction efficiencies and in vitro cytotoxic functions including degranulation, cytokine production, and cancer cell necrosis of both resultants PD-L1 CAR-NK cells were tested in vitro on two different PD-L1 low and high-expressing solid tumor cell lines.

RESULTS

Differentiated CAR‑modified UCB-CD34+ cells exhibited enhanced transduction efficiency. The expression of anti-PD-L1 CAR significantly (P < 0.05) enhanced the cytotoxicity of differentiated CAR‑modified UCB-CD34+ cells and CAR-modified UCB-CD34+-derived NK cells against PD-L1 high-expressing tumor cell line. In addition, CAR-modified UCB-CD34+-derived NK cells significantly (P < 0.05) restored the tumor-killing ability of exhausted PD-1 high T cells.

CONCLUSION

Considering the more efficient transduction in stem cells and the possibility of producing CAR-NK cell products with higher yields, this approach is recommended for studies in the field of CAR-NK cells. Also, a pre-clinical study is now necessary to evaluate the safety and efficacy of these two CAR-NK cells individually and in combination with other therapeutic approaches.

Mitochondrial tRNA pseudouridylation governs erythropoiesis

ABSTRACT

Pseudouridine is the most prevalent RNA modification, and its aberrant function is implicated in various human diseases. However, the specific impact of pseudouridylation on hematopoiesis remains poorly understood. Here, we investigated the role of transfer RNA (tRNA) pseudouridylation in erythropoiesis and its association with mitochondrial myopathy, lactic acidosis, and sideroblastic anemia syndrome (MLASA) pathogenesis. By using patient-specific induced pluripotent stem cells (iPSCs) carrying a genetic pseudouridine synthase 1 (PUS1) mutation and a corresponding mutant mouse model, we demonstrated impaired erythropoiesis in MLASA-iPSCs and anemia in the MLASA mouse model. Both MLASA-iPSCs and mouse erythroblasts exhibited compromised mitochondrial function and impaired protein synthesis. Mechanistically, we revealed that PUS1 deficiency resulted in reduced mitochondrial tRNA levels because of pseudouridylation loss, leading to aberrant mitochondrial translation. Screening of mitochondrial supplements aimed at enhancing respiration or heme synthesis showed limited effect in promoting erythroid differentiation. Interestingly, the mammalian target of rapamycin (mTOR) inhibitor rapamycin facilitated erythroid differentiation in MLASA-iPSCs by suppressing mTOR signaling and protein synthesis, and consistent results were observed in the MLASA mouse model. Importantly, rapamycin treatment partially ameliorated anemia phenotypes in a patient with MLASA. Our findings provide novel insights into the crucial role of mitochondrial tRNA pseudouridylation in governing erythropoiesis and present potential therapeutic strategies for patients with anemia facing challenges related to protein translation.

Comparative dissection of transcriptional landscapes of human iPSC-NK differentiation and NK cell development

Clinical and preclinical research has demonstrated that iPSC-derived NK (iNK) cells have a high therapeutic potential, yet poor understanding of the detailed process of their differentiation in vitro and their counterpart cell development in vivo has hindered therapeutic iNK cell production and engineering. Here we dissect the crucial differentiation of both fetal liver NK cells and iNK cells to enable the rational design of advanced iNK production protocols. We use a comparative analysis of single-cell RNA-seq (scRNA-seq) to pinpoint key factors lacking in the induced setting which we hypothesized would hinder iNK differentiation and/ or functionality. By analyzing key transcription factor regulatory networks, we discovered the importance of TBX21, EOMES, and STAT5A in the differentiation timeline. This analysis provides a blueprint for further engineering new iPSC lines to obtain iNK cells with enhanced functions. We validated this approach by creating a new line of STAT5A-iPSCs which can be differentiated to STAT5A-expressing macrophages with both NK cell and macrophage features such as perforin production, phagocytosis, and anti-tumor functions.

Building a human lung from pluripotent stem cells to model respiratory viral infections

To protect against the constant threat of inhaled pathogens, the lung is equipped with cellular defenders. In coordination with resident and recruited immune cells, this defence is initiated by the airway and alveolar epithelium following their infection with respiratory viruses. Further support for viral clearance and infection resolution is provided by adjacent endothelial and stromal cells. However, even with these defence mechanisms, respiratory viral infections are a significant global health concern, causing substantial morbidity, socioeconomic losses, and mortality, underlining the need to develop effective vaccines and antiviral medications. In turn, the identification of new treatment options for respiratory infections is critically dependent on the availability of tractable in vitro experimental models that faithfully recapitulate key aspects of lung physiology. For such models to be informative, it is important these models incorporate human-derived, physiologically relevant versions of all cell types that normally form part of the lungs anti-viral response. This review proposes a guideline using human induced pluripotent stem cells (iPSCs) to create all the disease-relevant cell types. iPSCs can be differentiated into lung epithelium, innate immune cells, endothelial cells, and fibroblasts at a large scale, recapitulating in vivo functions and providing genetic tractability. We advocate for building comprehensive iPSC-derived in vitro models of both proximal and distal lung regions to better understand and model respiratory infections, including interactions with chronic lung diseases.

Standardized generation of human iPSC-derived hematopoietic organoids and macrophages utilizing a benchtop bioreactor platform under fully defined conditions

BACKGROUND

There is a significant demand for intermediate-scale bioreactors in academic and industrial institutions to produce cells for various applications in drug screening and/or cell therapy. However, the application of these bioreactors in cultivating hiPSC-derived immune cells and other blood cells is noticeably lacking. To address this gap, we have developed a xeno-free and chemically defined intermediate-scale bioreactor platform, which allows for the generation of standardized human iPSC-derived hematopoietic organoids and subsequent continuous production of macrophages (iPSC-Mac).

METHODS

We describe a novel method for intermediate-scale immune cell manufacturing, specifically the continuous production of functionally and phenotypically relevant macrophages that are harvested on weekly basis for multiple weeks.

RESULTS

The continuous production of standardized human iPSC-derived macrophages (iPSC-Mac) from 3D hematopoietic organoids also termed hemanoids, is demonstrated. The hemanoids exhibit successive stage-specific embryonic development, recapitulating embryonic hematopoiesis. iPSC-Mac were efficiently and continuously produced from three different iPSC lines and exhibited a consistent and reproducible phenotype, as well as classical functionality and the ability to adapt towards pro- and anti-inflammatory activation stages. Single-cell transcriptomic analysis revealed high macrophage purity. Additionally, we show the ability to use the produced iPSC-Mac as a model for testing immunomodulatory drugs, exemplified by dexamethasone.

CONCLUSIONS

The novel method demonstrates an easy-to-use intermediate-scale bioreactor platform that produces prime macrophages from human iPSCs. These macrophages are functionally active and require no downstream maturation steps, rendering them highly desirable for both therapeutic and non-therapeutic applications.

NK cells as powerful therapeutic tool in cancer immunotherapy

BACKGROUND

Natural killer (NK) cells have gained considerable attention and hold great potential for their application in tumor immunotherapy. This is mainly due to their MHC-unrestricted and pan-specific recognition capabilities, as well as their ability to rapidly respond to and eliminate target cells. To artificially generate therapeutic NK cells, various materials can be utilized, such as peripheral blood mononuclear cells (PBMCs), umbilical cord blood (UCB), induced pluripotent stem cells (iPSCs), and NK cell lines. Exploiting the therapeutic potential of NK cells to treat tumors through in vivo and in vitro therapeutic modalities has yielded positive therapeutic results.

CONCLUSION

This review provides a comprehensive description of NK cell therapeutic approaches for tumors and discusses the current problems associated with these therapeutic approaches and the prospects of NK cell therapy for tumors.

iPSC-derived NK cells with site-specific integration of CAR19 and IL24 at the multi-copy rDNA locus enhanced antitumor activity and proliferation

The generation of chimeric antigen receptor-modified natural killer (CAR-NK) cells using induced pluripotent stem cells (iPSCs) has emerged as one of the paradigms for manufacturing off-the-shelf universal immunotherapy. However, there are still some challenges in enhancing the potency, safety, and multiple actions of CAR-NK cells. Here, iPSCs were site-specifically integrated at the ribosomal DNA (rDNA) locus with interleukin 24 (IL24) and CD19-specific chimeric antigen receptor (CAR19), and successfully differentiated into iPSC-derived NK (iNK) cells, followed by expansion using magnetic beads in vitro. Compared with the CAR19-iNK cells, IL24 armored CAR19-iNK (CAR19-IL24-iNK) cells showed higher cytotoxic capacity and amplification ability in vitro and inhibited tumor progression more effectively with better survival in a B-cell acute lymphoblastic leukaemia (B-ALL) (Nalm-6 (Luc1))-bearing mouse model. Interestingly, RNA-sequencing analysis showed that IL24 may enhance iNK cell function through nuclear factor kappa B (NFκB) pathway-related genes while exerting a direct effect on tumor cells. This study proved the feasibility and potential of combining IL24 with CAR-iNK cell therapy, suggesting a novel and promising off-the-shelf immunotherapy strategy.

Immune cells and RBCs derived from human induced pluripotent stem cells: method, progress, prospective challenges

Blood has an important role in the healthcare system, particularly in blood transfusions and immunotherapy. However, the occurrence of outbreaks of infectious diseases worldwide and seasonal fluctuations, blood shortages are becoming a major challenge. Moreover, the narrow specificity of immune cells hinders the widespread application of immune cell therapy. To address this issue, researchers are actively developing strategies for differentiating induced pluripotent stem cells (iPSCs) into blood cells in vitro. The establishment of iPSCs from terminally differentiated cells such as fibroblasts and blood cells is a straightforward process. However, there is need for further refinement of the protocols for differentiating iPSCs into immune cells and red blood cells to ensure their clinical applicability. This review aims to provide a comprehensive overview of the strategies and challenges facing the generation of iPSC-derived immune cells and red blood cells.

The paths and challenges of "off-the-shelf" CAR-T cell therapy: An overview of clinical trials

The advent of chimeric antigen receptor T cells (CAR-T cells) has made a tremendous revolution in the era of cancer immunotherapy, so that since 2017 eight CAR-T cell products have been granted marketing authorization. All of these approved products are generated from autologous sources, but this strategy faces several challenges such as time-consuming and expensive manufacturing process and reduced anti-tumor potency of patients' T cells due to the disease or previous therapies. The use of an allogeneic source can overcome these issues and provide an industrial, scalable, and standardized manufacturing process that reduces costs and provides faster treatment for patients. Nevertheless, for using allogeneic CAR-T cells, we are faced with the challenge of overcoming two formidable impediments: severe life-threatening graft-versus-host-disease (GvHD) caused by allogeneic CAR-T cells, and allorejection of allogeneic CAR-T cells by host immune cells which is called "host versus graft" (HvG). In this study, we reviewed recent registered clinical trials of allogeneic CAR-T cell therapy to analyze different approaches to achieve a safe and efficacious "off-the-shelf" source for chimeric antigen receptor (CAR) based immunotherapy.

Potentiation of natural killer cells to overcome cancer resistance to NK cell-based therapy and to enhance antibody-based immunotherapy

Natural killer (NK) cells are cellular components of the innate immune system that can recognize and suppress the proliferation of cancer cells. NK cells can eliminate cancer cells through direct lysis, by secreting perforin and granzymes, or through antibody-dependent cell-mediated cytotoxicity (ADCC). ADCC involves the binding of the Fc gamma receptor IIIa (CD16), present on NK cells, to the constant region of an antibody already bound to cancer cells. Cancer cells use several mechanisms to evade antitumor activity of NK cells, including the accumulation of inhibitory cytokines, recruitment and expansion of immune suppressor cells such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), modulation of ligands for NK cells receptors. Several strategies have been developed to enhance the antitumor activity of NK cells with the goal of overcoming cancer cells resistance to NK cells. The three main strategies to engineer and boost NK cells cytotoxicity include boosting NK cells with modulatory cytokines, adoptive NK cell therapy, and the employment of engineered NK cells to enhance antibody-based immunotherapy. Although the first two strategies improved the efficacy of NK cell-based therapy, there are still some limitations, including immune-related adverse events, induction of immune-suppressive cells and further cancer resistance to NK cell killing. One strategy to overcome these issues is the combination of monoclonal antibodies (mAbs) that mediate ADCC and engineered NK cells with potentiated anti-cancer activity. The advantage of using mAbs with ADCC activity is that they can activate NK cells, but also favor the accumulation of immune effector cells to the tumor microenvironment (TME). Several clinical trials reported that combining engineered NK cells with mAbs with ADCC activity can result in a superior clinical response compared to mAbs alone. Next generation of clinical trials, employing engineered NK cells with mAbs with higher affinity for CD16 expressed on NK cells, will provide more effective and higher-quality treatments to cancer patients.

Process engineering of natural killer cell-based immunotherapy

Cell therapy offers the potential for curative treatment of cancers. Although T cells have been the predominantly used cell type, natural killer (NK) cells have attracted great attention owing to their ability to kill cancer cells and because they are naturally suitable for allogeneic applications. Upon stimulation by cytokines or activation by a target cell, NK cells proliferate and expand their population. These cytotoxic NK cells can be cryopreserved and used as an off-the-shelf medicine. The production process for NK cells thus differs from that of autologous cell therapies. We briefly outline key biological features of NK cells, review the manufacturing technologies for protein biologics, and discuss their adaptation for developing robust NK cell biomanufacturing processes.

Good manufacturing practice production of CD34+ progenitor-derived NK cells for adoptive immunotherapy in acute myeloid leukemia

Allogeneic natural killer (NK) cell-based immunotherapy is a promising, well-tolerated adjuvant therapeutic approach for acute myeloid leukemia (AML). For reproducible NK cell immunotherapy, a homogenous, pure and scalable NK cell product is preferred. Therefore, we developed a good manufacturing practice (GMP)-compliant, cytokine-based ex vivo manufacturing process for generating NK cells from CD34+ hematopoietic stem and progenitor cells (HSPC). This manufacturing process combines amongst others IL15 and IL12 and the aryl hydrocarbon receptor antagonist StemRegenin-1 (SR1) to generate a consistent and active NK cell product that fits the requirements for NK cell immunotherapy well. The cell culture protocol was first optimized to generate NK cells with required expansion and differentiation capacity in GMP-compliant closed system cell culture bags. In addition, phenotype, antitumor potency, proliferative and metabolic capacity were evaluated to characterize the HSPC-NK product. Subsequently, seven batches were manufactured for qualification of the process. All seven runs demonstrated consistent results for proliferation, differentiation and antitumor potency, and preliminary specifications for the investigational medicinal product for early clinical phase trials were set. This GMP-compliant manufacturing process for HSPC-NK cells (named RNK001 cells) is used to produce NK cell batches applied in the clinical trial 'Infusion of ex vivo-generated allogeneic natural killer cells in combination with subcutaneous IL2 in patients with acute myeloid leukemia' approved by the Dutch Ethics Committee (EudraCT 2019-001929-27).

Generating hematopoietic cells from human pluripotent stem cells: approaches, progress and challenges

Human pluripotent stem cells (hPSCs) have been suggested as a potential source for the production of blood cells for clinical application. In two decades, almost all types of blood cells can be successfully generated from hPSCs through various differentiated strategies. Meanwhile, with a deeper understanding of hematopoiesis, higher efficiency of generating progenitors and precursors of blood cells from hPSCs is achieved. However, how to generate large-scale mature functional cells from hPSCs for clinical use is still difficult. In this review, we summarized recent approaches that generated both hematopoietic stem cells and mature lineage cells from hPSCs, and remarked their efficiency and mechanisms in producing mature functional cells. We also discussed the major challenges in hPSC-derived products of blood cells and provided some potential solutions. Our review summarized efficient, simple, and defined methodologies for developing good manufacturing practice standards for hPSC-derived blood cells, which will facilitate the translation of these products into the clinic.

Germline Neurofibromin 1 mutation enhances the anti-tumour immune response and decreases juvenile myelomonocytic leukaemia tumourigenicity

Juvenile myelomonocytic leukaemia (JMML) is an aggressive paediatric leukaemia characterized by mutations in five canonical RAS pathway genes, including the NF1 gene. JMML is driven by germline NF1 gene mutations, with additional somatic aberrations resulting in the NF1 biallelic inactivation, leading to disease progression. Germline mutations in the NF1 gene alone primarily cause benign neurofibromatosis type 1 (NF1) tumours rather than malignant JMML, yet the underlying mechanism remains unclear. Here, we demonstrate that with reduced NF1 gene dose, immune cells are promoted in anti-tumour immune response. Comparing the biological properties of JMML and NF1 patients, we found that not only JMML but also NF1 patients driven by NF1 mutations could increase monocytes generation. But monocytes cannot further malignant development in NF1 patients. Utilizing haematopoietic and macrophage differentiation from iPSCs, we revealed that NF1 mutations or knockout (KO) recapitulated the classical haematopoietic pathological features of JMML with reduced NF1 gene dose. NF1 mutations or KO promoted the proliferation and immune function of NK cells and iMacs derived from iPSCs. Moreover, NF1-mutated iNKs had a high capacity to kill NF1-KO iMacs. NF1-mutated or KO iNKs administration delayed leukaemia progression in a xenograft animal model. Our findings demonstrate that germline NF1 mutations alone cannot directly drive JMML development and suggest a potential cell immunotherapy for JMML patients.

CAR-NK cell therapy for glioblastoma: what to do next?

Glioblastoma is a malignant tumor with the highest morbidity and mortality in the central nervous system. Conventional surgical resection combined with radiotherapy or chemotherapy has a high recurrence rate and poor prognosis. The 5-year survival rate of patients is less than 10%. In tumor immunotherapy, CAR-T cell therapy represented by chimeric antigen receptor-modified T cells has achieved great success in hematological tumors. However, the application of CAR-T cells in solid tumors such as glioblastoma still faces many challenges. CAR-NK cells are another potential adoptive cell therapy strategy after CAR-T cells. Compared with CAR-T cell therapy, CAR-NK cells have similar anti-tumor effects. CAR-NK cells can also avoid some deficiencies in CAR-T cell therapy, a research hotspot in tumor immunity. This article summarizes the preclinical research status of CAR-NK cells in glioblastoma and the problems and challenges faced by CAR-NK in glioblastoma.

Leveraging CD16 fusion receptors to remodel the immune response for enhancing anti-tumor immunotherapy in iPSC-derived NK cells

BACKGROUND

The cytotoxicity of NK cells is largely dependent on IgG Fc receptor CD16a, which mediates antibody-dependent cell-mediated cytotoxicity (ADCC). The high-affinity and non-cleavable CD16 (hnCD16) is developed and demonstrated a multi-tumor killing potential. However, the hnCD16 receptor activates a single CD16 signal and provides limited tumor suppression. How to exploit the properties of hnCD16 and incorporate NK cell-specific activation domains is a promising development direction to further improve the anti-tumor activity of NK cells.

METHODS

To expand the applications of hnCD16-mediated ADCC for NK cell-based immunotherapy in cancer, we designed the hnCD16 Fusion Receptor (FR) constructs with the ectodomain of hnCD16 fused with NK cell-specific activating domains in the cytoplasm. FR constructs were transduced into CD16-negative NK cell line and human iPSC-derived NK (iNK) cells and effective FR constructs were screened. The up-regulation of immune activation- and cytokine-releasing-related pathways in FR-transduced NK cells was screened and validated by RNA sequencing and multiplex cytokines release assay, respectively. The tumor-killing efficiency was tested in vitro and in vivo via co-culture with tumor cell lines and xenograft mice-bearing human B-cell lymphoma, respectively.

RESULTS

We screened the most effective combination to kill B cell lymphoma, which was fused with the ectodomain of hnCD16a, NK-specific co-stimulators (2B4 and DAP10) and CD3ζ in cytoplasmic domains. The screened construct showed excellent cytotoxicity effects and sharp multiple cytokines releasing both in the NK cell line and iNK cells. The transcriptomic analysis and validation assays of hnCD16- and hnCD16FR-transduced NK cells showed that hnCD16FR transduction remodeled immune-related transcriptome in NK cells, where significant upregulation of genes related to cytotoxicity, high cytokines releasing, induced tumor cell apoptosis, and ADCC in comparison with hnCD16 transduction were highlighted. In vivo xenograft studies demonstrated that a single low-dose regimen of engineered hnCD16FR iPSC-derived NK cells co-administered with anti-CD20 mAb treatment mediated potent activity and significantly improved survival.

CONCLUSION

We developed a novel hnCD16FR construct that exhibits more potent cytotoxicity than reported hnCD16, which is a promising approach to treat malignancies with improved ADCC properties. We also offer a rationale for NK activation domains that remodel immune response to enhance CD16 signaling in NK cells.

Advancing cell-based cancer immunotherapy through stem cell engineering

Advances in cell-based therapy, particularly CAR-T cell therapy, have transformed the treatment of hematological malignancies. Although an important step forward for the field, autologous CAR-T therapies are hindered by high costs, manufacturing challenges, and limited efficacy against solid tumors. With ongoing progress in gene editing and culture techniques, engineered stem cells and their application in cell therapy are poised to address some of these challenges. Here, we review stem cell-based immunotherapy approaches, stem cell sources, gene engineering and manufacturing strategies, therapeutic platforms, and clinical trials, as well as challenges and future directions for the field.

Single-cell transcriptomics reveals that tumor-infiltrating natural killer cells are activated by localized ablative immunotherapy and share anti-tumor signatures induced by immune checkpoint inhibitors

Rationale

Natural killer (NK) cells provide protective anti-cancer immunity. However, the cancer therapy induced activation gene signatures and pathways in NK cells remain unclear.

Methods

We applied a novel localized ablative immunotherapy (LAIT) by synergizing photothermal therapy (PTT) with intra-tumor delivering of the immunostimulant N-dihydrogalactochitosan (GC), to treat breast cancer using a mammary tumor virus-polyoma middle tumor-antigen (MMTV-PyMT) mouse model. We performed single-cell RNA sequencing (scRNAseq) analysis to unveil the cellular heterogeneity and compare the transcriptional alterations induced by PTT, GC, and LAIT in NK cells within the tumor microenvironment (TME).

Results

ScRNAseq showed that NK subtypes, including cycling, activated, interferon-stimulated, and cytotoxic NK cells. Trajectory analysis revealed a route toward activation and cytotoxicity following pseudotime progression. Both GC and LAIT elevated gene expression associated with NK cell activation, cytolytic effectors, activating receptors, IFN pathway components, and cytokines/chemokines in NK subtypes. Single-cell transcriptomics analysis using immune checkpoint inhibitor (ICI)-treated animal and human samples revealed that ICI-induced NK activation and cytotoxicity across several cancer types. Furthermore, ICI-induced NK gene signatures were also induced by LAIT treatment. We also discovered that several types of cancer patients had significantly longer overall survival when they had higher expression of genes in NK cells that were also specifically upregulated by LAIT.

Conclusion

Our findings show for the first time that LAIT activates cytotoxicity in NK cells and the upregulated genes positively correlate with beneficial clinical outcomes for cancer patients. More importantly, our results further establish the correlation between the effects of LAIT and ICI on NK cells, hence expanding our understanding of mechanism of LAIT in remodeling TME and shedding light on the potentials of NK cell activation and anti-tumor cytotoxic functions in clinical applications.

'Off the shelf' immunotherapies: Generation and application of pluripotent stem cell-derived immune cells

In recent years, great strides have been made toward the development of immune cell-based therapies in the treatment of refractory malignancies. Primary T cells and NK cells armed with chimeric antigen receptors have achieved tremendous clinical success especially in patients with leukaemia and lymphoma. However, the autologous origin of these effector cells means that a single batch of laboriously engineered cells treats only a certain patient, leading to high cost, ununiform product quality, and risk of delay in treatment, and therefore results in restricted accessibility of these therapies to the overwhelming majority of the patients. Addressing these tricky obstacles calls for the development of universal immune cell products that can be provided 'off the shelf' in a large amount. Pluripotent stem cells (PSCs), owing to their unique capacity of self-renewal and the potential of multi-lineage differentiation, offer an unlimited cell source to generate uniform and scalable engineered immune cells. This review discusses the major advances in the development of PSC-derived immune cell differentiation approaches and their therapeutic potential in treating both hematologic malignancies and solid tumours. We also consider the potency of PSC-derived immune cells as an alternative therapeutic strategy for other diseases, such as autoimmune diseases, fibrosis, infections, et al.

Emerging Targeted Therapies for HER2-Positive Breast Cancer

Breast cancer is the most common cancer in women and the leading cause of death. HER2 overexpression is found in approximately 20% of breast cancers and is associated with a poor prognosis and a shorter overall survival. Tratuzumab, a monoclonal antibody directed against the HER2 receptor, is the standard of care treatment. However, a third of the patients do not respond to therapy. Given the high rate of resistance, other HER2-targeted strategies have been developed, including monoclonal antibodies such as pertuzumab and margetuximab, trastuzumab-based antibody drug conjugates such as trastuzumab-emtansine (T-DM1) and trastuzumab-deruxtecan (T-DXd), and tyrosine kinase inhibitors like lapatinib and tucatinib, among others. Moreover, T-DXd has proven to be of use in the HER2-low subtype, which suggests that other HER2-targeted therapies could be successful in this recently defined new breast cancer subclassification. When patients progress to multiple strategies, there are several HER2-targeted therapies available; however, treatment options are limited, and the potential combination with other drugs, immune checkpoint inhibitors, CAR-T cells, CAR-NK, CAR-M, and vaccines is an interesting and appealing field that is still in development. In this review, we will discuss the highlights and pitfalls of the different HER2-targeted therapies and potential combinations to overcome metastatic disease and resistance to therapy.

Allogeneic natural killer cell therapy

Interest in adoptive cell therapy for treating cancer is exploding owing to early clinical successes of autologous chimeric antigen receptor (CAR) T lymphocyte therapy. However, limitations using T cells and autologous cell products are apparent as they (1) take weeks to generate, (2) utilize a 1:1 donor-to-patient model, (3) are expensive, and (4) are prone to heterogeneity and manufacturing failures. CAR T cells are also associated with significant toxicities, including cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, and prolonged cytopenias. To overcome these issues, natural killer (NK) cells are being explored as an alternative cell source for allogeneic cell therapies. NK cells have an inherent ability to recognize cancers, mediate immune functions of killing and communication, and do not induce graft-versus-host disease, cytokine release syndrome, or immune effector cell-associated neurotoxicity syndrome. NK cells can be obtained from blood or cord blood or be derived from hematopoietic stem and progenitor cells or induced pluripotent stem cells, and can be expanded and cryopreserved for off-the-shelf availability. The first wave of point-of-care NK cell therapies led to the current allogeneic NK cell products being investigated in clinical trials with promising preliminary results. Basic advances in NK cell biology and cellular engineering have led to new translational strategies to block inhibition, enhance and broaden target cell recognition, optimize functional persistence, and provide stealth from patients' immunity. This review details NK cell biology, as well as NK cell product manufacturing, engineering, and combination therapies explored in the clinic leading to the next generation of potent, off-the-shelf cellular therapies for blood cancers.

Engineered and banked iPSCs for advanced NK- and T-cell immunotherapies

The development of methods to derive induced pluripotent stem cells (iPSCs) has propelled stem cell research, and has the potential to revolutionize many areas of medicine, including cancer immunotherapy. These cells can be propagated limitlessly and can differentiate into nearly any specialized cell type. The ability to perform precise multigene engineering at the iPSC stage, generate master cell lines after clonal selection, and faithfully promote differentiation along natural killer (NK) cells and T-cell lineages is now leading to new opportunities for the administration of off-the-shelf cytotoxic lymphocytes with direct antigen targeting to treat patients with relapsed/refractory cancer. In this review, we highlight the recent progress in iPSC editing and guided differentiation in the development of NK- and T-cell products for immunotherapy. We also discuss some of the potential barriers that remain in unleashing the full potential of iPSC-derived cytotoxic effector cells in the adoptive transfer setting, and how some of these limitations may be overcome through gene editing.

Non-Conventional Allogeneic Anti-BCMA Chimeric Antigen Receptor-Based Immune Cell Therapies for Multiple Myeloma Treatment

MM, characterized by the progressive accumulation of clonal plasma cells in bone marrow, remains a severe medical problem globally. Currently, almost all MM patients who have received standard treatments will eventually relapse. Autologous anti-BCMA CAR-T cells are one of the FDA-approved immunotherapy cell-based products for treating adults with relapsed or refractory (r/r) multiple myeloma. However, this type of CAR-T cell product has several limitations, including high costs, long manufacturing times, and possible manufacturing failure, which significantly hinder its wider application for more patients. In this review, we summarized the current development stage of applying other types of immune cells to bring the anti-BCMA CAR-T therapy from autologous to allogeneic. In general, anti-BCMA CAR gene-edited αβ T cells and CAR-Natural Killer (NK) cells are at the forefront, with multiple clinical trials ongoing, while CAR-γδ T cells and CAR-invariant Natural Killer T (iNKT) cells are still in pre-clinical studies. Other immune cells such as macrophages, B cells, and dendritic cells have been mainly developed to target other antigens and have the potential to be used to target BCMA. Nevertheless, additional regulatory requirements might need to be taken into account in developing these non-conventional allogenic anti-BCMA CAR-based cell products.

Emerging frontiers in immuno- and gene therapy for cancer

BACKGROUND AIMS

The field of cell and gene therapy in oncology has moved rapidly since 2017 when the first cell and gene therapies, Kymriah followed by Yescarta, were approved by the Food and Drug Administration in the United States, followed by multiple other countries. Since those approvals, several new products have gone on to receive approval for additional indications. Meanwhile, efforts have been made to target different cancers, improve the logistics of delivery and reduce the cost associated with novel cell and gene therapies. Here, we highlight various cell and gene therapy-related technologies and advances that provide insight into how these new technologies will speed the translation of these therapies into the clinic.

CONCLUSIONS

In this review, we provide a broad overview of the current state of cell and gene therapy-based approaches for cancer treatment - discussing various effector cell types and their sources, recent advances in both CAR and non-CAR genetic modifications, and highlighting a few promising approaches for increasing in vivo efficacy and persistence of therapeutic drug products.

Natural killer cells in sepsis: Friends or foes?

Sepsis is one of the major causes of death in the hospital worldwide. The pathology of sepsis is tightly associated with dysregulation of innate immune responses. The contribution of macrophages, neutrophils, and dendritic cells to sepsis is well documented, whereas the role of natural killer (NK) cells, which are critical innate lymphoid lineage cells, remains unclear. In some studies, the activation of NK cells has been reported as a risk factor leading to severe organ damage or death. In sharp contrast, some other studies revealed that triggering NK cell activity contributes to alleviating sepsis. In all, although there are several reports on NK cells in sepsis, whether they exert detrimental or protective effects remains unclear. Here, we will review the available experimental and clinical studies about the opposing roles of NK cells in sepsis, and we will discuss the prospects for NK cell-based immunotherapeutic strategies for sepsis.

The prospect of genetically engineering natural killer cells for cancer immunotherapy

The use of natural killer (NK) cells in cancer immunotherapy demonstrates promising potential, yet its efficacy is often limited due to the loss of tumor-killing capacity and lack of specificity in vivo. Here, we review current approaches to confer enhanced tumor-killing capacity and specificity by genetic engineering. Increasing sensitivity to cytokines and protecting NK cells from the immune checkpoint endowed sustainability of NK cells in the tumor microenvironment. Transducing chimeric antigen receptor (CAR) in NK cells successfully targeted both hematologic and solid tumors in preclinical models. The use of human pluripotent stem cells as an expandable and genetically amenable platform offers a stable source of engineered NK cells for cancer immunotherapy. We highlight that CAR-NK cells from human pluripotent stem cells are a promising approach for cancer immunotherapy.

In vitro systems to study inborn errors of immunity using human induced pluripotent stem cells

In the last two decades, the exponential progress in the field of genetics could reveal the genetic impact on the onset and progression of several diseases affecting the immune system. This knowledge has led to the discovery of more than 400 monogenic germline mutations, also known as “inborn errors of immunity (IEI)”. Given the rarity of various IEI and the clinical diversity as well as the limited available patients’ material, the continuous development of novel cell-based in vitro models to elucidate the cellular and molecular mechanisms involved in the pathogenesis of these diseases is imperative. Focusing on stem cell technologies, this review aims to provide an overview of the current available in vitro models used to study IEI and which could lay the foundation for new therapeutic approaches. We elaborate in particular on the use of induced pluripotent stem cell-based systems and their broad application in studying IEI by establishing also novel infection culture models. The review will critically discuss the current limitations or gaps in the field of stem cell technology as well as the future perspectives from the use of these cell culture systems.

Multifaceted characterization of the biological and transcriptomic signatures of natural killer cells derived from cord blood and placental blood

Background

Perinatal blood including umbilical cord blood and placental blood are splendid sources for allogeneic NK cell generation with high cytotoxicity of combating pathogenic microorganism and malignant tumor. Despite the generation of NK cells from the aforementioned perinatal blood, yet the systematical and detailed information of the biological and transcriptomic signatures of UC-NKs and P-NKs before large-scale clinical applications in disease remodeling is still largely obscure.

Methods

Herein, we took advantage of the “3IL”-based strategy for high-efficient generation of NK cells from umbilical cord blood and placental blood (UC-NKs and P-NKs), respectively. On the one hand, we conducted flow cytometry (FCM) assay and coculture to evaluate the subpopulations, cellular vitality and cytotoxic activity of the aforementioned NK cells. On the other hand, with the aid of RNA-SEQ and multiple bioinformatics analyses, we further dissected the potential diversities of UC-NKs and P-NKs from the perspectives of transcriptomes.

Results

On the basis of the “3IL” strategy, high-efficient NKs were generated from mononuclear cells (MNCs) in perinatal blood. P-NKs revealed comparable ex vivo expansion but preferable activation and cytotoxicity upon K562 cells over UC-NKs. Both of the two NKs showed diversity in cellular vitality and transcriptome including apoptotic cells, cell cycle, gene expression profiling and the accompanied multifaceted biological processes.

Conclusions

Our data revealed the multifaceted similarities and differences of UC-NKs and P-NKs both at the cellular and molecular levels. Our findings supply new references for allogeneic NK cell-based immunotherapy in regenerative medicine and will benefit the further exploration for illuminating the underlying mechanism as well.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02697-6.

Current Progress of CAR-NK Therapy in Cancer Treatment

Simple Summary

Chimeric antigen receptor (CAR)-T and -natural killer (NK) therapies are promising in cancer treatment. CAR-NK therapy gains great attention due to the lack of adverse effects observed in CAR-T therapies and to the NK cells’ unique mechanisms of recognizing target cells. Off-the-shelf products are in urgent need, not only for good yields, but also for lower cost and shorter preparation time. The current progress of CAR-NK therapy is discussed.

Abstract

CD8⁺ T cells and natural killer (NK) cells eliminate target cells through the release of lytic granules and Fas ligand (FasL)-induced target cell apoptosis. The introduction of chimeric antigen receptor (CAR) makes these two types of cells selective and effective in killing cancer cells. The success of CAR-T therapy in the treatment of acute lymphoblastic leukemia (ALL) and other types of blood cancers proved that the immunotherapy is an effective approach in fighting against cancers, yet adverse effects, such as graft versus host disease (GvHD) and cytokine release syndrome (CRS), cannot be ignored for the CAR-T therapy. CAR-NK therapy, then, has its advantage in lacking these adverse effects and works as effective as CAR-T in terms of killing. Despite these, NK cells are known to be hard to transduce, expand in vitro, and sustain shorter in vivo comparing to infiltrated T cells. Moreover, CAR-NK therapy faces challenges as CAR-T therapy does, e.g., the time, the cost, and the potential biohazard due to the use of animal-derived products. Thus, enormous efforts are needed to develop safe, effective, and large-scalable protocols for obtaining CAR-NK cells. Here, we reviewed current progress of CAR-NK therapy, including its biological properties, CAR compositions, preparation of CAR-NK cells, and clinical progresses. We also discussed safety issues raised from genetic engineering. We hope this review is instructive to the research community and a broad range of readers.

Stem Cell Therapy and Innate Lymphoid Cells

Innate lymphoid cells have the capability to communicate with other immune cell types to coordinate the immune system functioning during homeostasis and inflammation. However, these cells behave differently at the functional level, unlike T cells, these cells do not need antigen receptors for activation because they are activated by the interaction of their receptor ligation. In hematopoietic stem cell transplantation (HSCT), T cells and NK cells have been extensively studied but very few studies are available on ILCs. In this review, an attempt has been made to provide current information related to NK and ILCs cell-based stem cell therapies and role of the stem cells in the regulation of ILCs as well. Also, the latest information on the differentiation of NK cells and ILCs from CD34+ hematopoietic stem cells is covered in the article.

Potential of chimeric antigen receptor (CAR)-redirected immune cells in breast cancer therapies: Recent advances

Despite substantial developments in conventional treatments such as surgery, chemotherapy, radiotherapy, endocrine therapy, and molecular-targeted therapy, breast cancer remains the leading cause of cancer mortality in women. Currently, chimeric antigen receptor (CAR)-redirected immune cell therapy has emerged as an innovative immunotherapeutic approach to ameliorate survival rates of breast cancer patients by eliciting cytotoxic activity against cognate tumour-associated antigens expressing tumour cells. As a crucial component of adaptive immunity, T cells and NK cells, as the central innate immune cells, are two types of pivotal candidates for CAR engineering in treating solid malignancies. However, the biological distinctions between NK cells- and T cells lead to differences in cancer immunotherapy outcomes. Likewise, optimal breast cancer removal via CAR-redirected immune cells requires detecting safe target antigens, improving CAR structure for ideal immune cell functions, promoting CAR-redirected immune cells filtration to the tumour microenvironment (TME), and increasing the ability of these engineered cells to persist and retain within the immunosuppressive TME. This review provides a concise overview of breast cancer pathogenesis and its hostile TME. We focus on the CAR-T and CAR-NK cells and discuss their significant differences. Finally, we deliver a summary based on recent advancements in the therapeutic capability of CAR-T and CAR-NK cells in treating breast cancer.

Generation of universal natural killer cells from a cryopreserved cord blood mononuclear cell-derived induced pluripotent stem cell library

Natural killer (NK) cells play a key role in innate immunity and are regarded as a promising candidate for cellular immunotherapy. Natural killer cells may be generated from different sources, including induced pluripotent stem cells (iPSCs); these stem cells produce an abundant amount of NK cells to meet the needs of a wide range of clinical applications. Autologous iPSCs are expensive and labor-intensive to prepare, while allogeneic iPSCs require human leukocyte antigen (HLA) matched cells to avoid the risk of immune rejection. In the current study, we prepared HLA-matched iPSCs using HLA common haplotype homozygous (HLAh) donors from cryopreserved human cord blood (CB) sourced from the Tianjin Cord Blood Public Bank. This approach was designed to generate a CB-derived iPSC library from HLAh donors and use it to produce off-the-shelf NK cells. Starting with readily available cryopreserved CB mononuclear cells (cryoCBMCs), we produced cryoCBMC-derived iPSCs (cryoCB-iPSCs). These cryoCB-iPSCs were induced to generate embryoid bodies (EBs) using an improved 3D suspension culture method, and induced NK (iNK) cells were differentiated from EBs. iNK cells expressed specific surface markers of NK cells, exhibited cytotoxicity comparable with NK cells generated from CB (CB-NK) and peripheral blood (PB-NK), and expressed lower levels of KIRs and HLA-DR compared to CB-NK and PB-NK. Taken together, we have shown that an iPSC library can be established from HLAh cryoCBMCs, and cryoCB-iPSCs can be used to generate a large number of 'universal' NK cells for future clinical applications.

Quality criteria for in vitro human pluripotent stem cell-derived models of tissue-based cells

The advent of the technology to isolate or generate human pluripotent stem cells provided the potential to develop a wide range of human models that could enhance understanding of mechanisms underlying human development and disease. These systems are now beginning to mature and provide the basis for the development of in vitro assays suitable to understand the biological processes involved in the multi-organ systems of the human body, and will improve strategies for diagnosis, prevention, therapies and precision medicine. Induced pluripotent stem cell lines are prone to phenotypic and genotypic changes and donor/clone dependent variability, which means that it is important to identify the most appropriate characterization markers and quality control measures when sourcing new cell lines and assessing differentiated cell and tissue culture preparations for experimental work. This paper considers those core quality control measures for human pluripotent stem cell lines and evaluates the state of play in the development of key functional markers for their differentiated cell derivatives to promote assurance of reproducibility of scientific data derived from pluripotent stem cell-based systems.

Natural killer cells: Innate immune system as a part of adaptive immunotherapy in hematological malignancies

Natural killer (NK) cells are part of a phylogenetically old defense system, which is characterized by its strong cytolytic function against physiologically stressed cells such as tumor cells and virus-infected cells. Their use in the treatment of hematological malignancies may be more advantageous in several ways when compared with the already established T lymphocyte-based immunotherapy. Given the different mechanisms of action, allogeneic NK cell products can be produced in a non-personal based manner without the risk of the formidable graft-versus-host disease. Advanced manufacturing processes are capable of producing NK cells relatively easily in large and clinically sufficient numbers, useable without subsequent manipulations or after genetic modifications, which can solve the lack of specificity and improve clinical efficacy of NK cell products. This review summarizes the basic characteristics of NK cells and provides a quick overview of their sources. Results of clinical trials in hematological malignancies are presented, and strategies on how to improve the clinical outcome of NK cell therapy are discussed.