Evidence for Killing of Mesenchymal Stem Cells (MSC) by Autologous Natural Killer Lymphocytes.

Abstract In this study, Mesenchymal Stem Cells (MSC) were obtained from bone marrow of 10 patients suffering from acute myeloid leukemia (AML), six M0/1 two M2, and two M5 (according to the FAB classification), 8 out of 10 in post-chemotherapy complete remission. These cells differentiated into adipocytes or osteoblasts under appropriate culture conditions. MSC were CD44+, CD73a+ CD73b+ CD105+, beta1 integrin+, ICAM1+, HLA-I+, HLA-II+ (variable proportions), CD45−, CD31−, CD34− and they constitutively expressed the stress-inducible MHC-related molecules MIC-A and the UL16 (induced at the surface of cells infected by cytomegalovirus) binding protein ULBP3. These molecules are reported ligands for the NKG2D receptor expressed by natural killer (NK) and CD8+ T lymphocytes, effector cells that are thought to play a role in host defence against tumors. NK cells have also been shown to regulate normal differentiation of hemopoietic precursor into the myeloid or lymphoid cell lineage. Moreover, it has been stated that NK cells are not able to damage autologous cells, as they receive negative signals through inhibitory receptors, including killer Ig-like receptors (KIR) or C-type lectin inhibitory receptors (CLIR), which bind to HLA-I discrete alleles. Surprisingly, we found that autologous IL2-activated, but not freshly isolated, NK cells lysed MSC, while T lymphocytes did not kill self or non-self MSC. Binding of ICAM-1 expressed by MSC to its receptor, the integrin LFA-1, expressed by NK cells plays a key role in MSC/NK interaction. More importantly, NKG2D/MICA and/or NKG2D/ULBP3 engagement is responsible for the delivery of lethal hit. Conversely, it appears that HLA-I molecules do not protect MSC from NK cell-mediated injury. Taken together, these data suggest that NK cells, when activated as it may occur during the first response to viral infections, are able to eliminate MSC, thus altering the normal interactions with hemopoietic precursors and possibly affecting their differentiation. This mechanism might also contribute to the development of aberrant precursors as observed in acute leukaemias.

Download Full-text

The endometrium as a source of mesenchymal stem cells in domestic animals and possible applications in veterinary medicine

Veterinaria México OA ◽

10.21753/vmoa.4.3.441 ◽

2017 ◽

Vol 4 (3) ◽

Cited By ~ 1

Author(s):

Ana G. Serrato López ◽

Juan J. Montesinos Montesinos ◽

Santiago R. Anzaldúa Arce

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Veterinary Medicine ◽

T Lymphocytes ◽

Nk Cells ◽

Domestic Animals ◽

Clinical Tool ◽

Cellular Contact ◽

Activated T Lymphocytes

Mesenchymal stem cells (MSCs) have been isolated from the endometrium of humans, mice, cows, pigs and ewes. Typically, these cells are detected in the deep regions of the endometrium, closer to the union with the myometrium. MSCs possess characteristics such as clonogenicity and multipotentiality since they can differentiate in vitro into adipogenic, chondrogenic and osteogenic lineages. These cells can be induced to differentiate in vitro not only into the mesodermal lineage but also into the endodermal and ectodermal lineages. Therefore, MSCs show a great regenerative capacity for various organs and tissues, including the endometrium. Some advantages of endometrial MSCs compared with other MSC sources are their immune modulating activity, their ease of obtainment, and the amount of sample that may be collected. The study of endometrial MSCs in domestic animals is a new and promising field because increasing our understanding of the physiology and biology of these cells may lead to a better understanding of the physiopathology of reproductive diseases, and the development of treatment methods for infertility problems. In other veterinary medicine fields, MSCs can be used for the treatment of autoimmune diseases, cardiac affections, musculoskeletal and articular lesions, muscle degeneration, type 1 diabetes, urinary tract diseases, neurodegenerative processes and tumours. Finally, MSCs are also an important clinical tool for tissue engineering and regenerative medicine. The aim of this review is to present an updated outlook of the knowledge regarding endometrial MSCs and their possible applications in veterinary medicine.Figure 1: Immunoregulatory ability of MSCs. MSCs regulate the functions of NK cells, dendritic cells (DC) and T lymphocytes. The immunosuppressive effect may occur through the secretion of different factors or through cellular contact (black arrows). The former pathway involves TGFß, HGF, IL-10, PGE2, and HLA-G5, whereas the latter pathway involves the products of IDO enzyme activity, PD-L1, HLA-G1, ICAM-I and VCAM-I. Pro-inflammatory cytokines (IFN-?) secreted by NK cells and activated T lymphocytes favour the immunoregulatory activity of MSCs (dotted lines), because they increase or induce the secretion of molecules that regulate the functions of the distinct cellular components of the immune system. Modified from Montesinos et al, and Ma et al.19,66

Download Full-text

Activation Status Dictates the Function of Unlicensed Natural Killer Cells

Blood Advances ◽

10.1182/bloodadvances.2021004589 ◽

2021 ◽

Author(s):

Ethan G Aguilar ◽

Cordelia Dunai ◽

Sean J. Judge ◽

Anthony Elston Zamora ◽

Lam T. Khuat ◽

...

Keyword(s):

Viral Infection ◽

Nk Cells ◽

Natural Killer ◽

Viral Infections ◽

Nk Cell ◽

T Cell Response ◽

High Dose ◽

Hematopoietic Stem ◽

Innate Defense ◽

Activation Status

Natural Killer (NK) cells are involved in innate defense against viral infection and cancer. NK cells can be divided into subsets based on the ability of different receptors to bind to major histocompatibility (MHC) class I molecules resulting in differential responses upon activation in a process called "licensing" or "arming". NK cells expressing receptors that bind self-MHC are considered licensed due to augmented effector lytic function capability compared to unlicensed subsets. However, we demonstrated unlicensed NK subsets instead positively regulate the adaptive T cell response during viral infections due to localization and cytokine production. We demonstrate here that the differential effects of the two types of NK subsets is contingent on the environment using viral infection and hematopoietic stem cell transplantation (HSCT) models. Infection of mice with high-dose (HD) MCMV leads to a loss of licensing-associated differences as compared to mice with low-dose infection, as the unlicensed NK subset no longer localized in lymph nodes (LN), but instead remained at the site of infection. Similarly, the patterns observed during HD infection paralleled with the phenotypes of both human and mouse NK cells in a HSCT setting where NK cells exhibit an activated phenotype. However, in contrast to effects of subset depletion in T-replete models, the licensed NK cell subsets still dominated anti-viral responses post-HSCT. Overall, our results highlight the intricate tuning of the NK cells and how it impacts overall immune responses with regard to licensing patterns, as it is dependent on the level of stimulation and their activation status.

Download Full-text

The Effects of Mesenchymal Stem Cells on Antimelanoma Immunity Depend on the Timing of Their Administration

Stem Cells International ◽

10.1155/2020/8842659 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Dragana Miloradovic ◽

Dragica Miloradovic ◽

Bojana Simovic Markovic ◽

Aleksandar Acovic ◽

Carl Randall Harrell ◽

...

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

T Lymphocytes ◽

Tumor Growth ◽

Nk Cells ◽

Plasma Levels ◽

Th17 Cells ◽

Antitumor Immunity ◽

Granzyme B ◽

Lower Plasma

There is still a lively debate about whether mesenchymal stem cells (MSCs) promote or suppress antitumor immune response. Although several possible explanations have been proposed, including different numbers of injected and engrafted MSCs, heterogeneity in phenotype, and function of tumor cells, the exact molecular mechanisms responsible for opposite effects of MSCs in modulation of antitumor immunity are still unknown. Herewith, we used a B16F10 murine melanoma model to investigate whether timing of MSC administration in tumor-bearing mice was crucially important for their effects on antitumor immunity. MSCs, intravenously injected 24 h after melanoma induction (B16F10+MSC1d-treated mice), significantly enhanced natural killer (NK) and T cell-driven antitumor immunity, suppressed tumor growth, and improved survival of melanoma-bearing animals. Significantly higher plasma levels of antitumorigenic cytokines (TNF-α and IFN-γ), remarkably lower plasma levels of immunosuppressive cytokines (TGF-β and IL-10), and a significantly higher number of tumor-infiltrating, IFN-γ-producing, FasL- and granzyme B-expressing NK cells, IL-17-producing CD4+Th17 cells, IFN-γ- and TNF-α-producing CD4+Th1 cells, and CD8+cytotoxic T lymphocytes (CTLs) were observed in B16F10+MSC1d-treated mice. On the contrary, MSCs, injected 14 days after melanoma induction (B16F10+MSC14d-treated mice), promoted tumor growth by suppressing antigen-presenting properties of tumor-infiltrating dendritic cells (DCs) and macrophages and by reducing tumoricidal capacity of NK cells and T lymphocytes. Significantly higher plasma levels of TGF-β and IL-10, remarkably lower plasma levels of TNF-α and IFN-γ, and significantly reduced number of tumor-infiltrating, I-A-expressing, and IL-12-producing macrophages, CD80- and I-A-expressing DCs, granzyme B-expressing CTLs and NK cells, IFN-γ- and IL-17-producing CTLs, CD4+Th1, and Th17 cells were observed in B16F10+MSC14d-treated animals. In summing up, the timing of MSC administration into the tumor microenvironment was crucially important for MSC-dependent modulation of antimelanoma immunity. MSCs transplanted during the initial phase of melanoma growth exerted tumor-suppressive effect, while MSCs injected during the progressive stage of melanoma development suppressed antitumor immunity and enhanced tumor expansion.

Download Full-text

Generation of human natural killer cells from immature progenitors does not require marrow stromal cells

Blood ◽

10.1182/blood.v84.3.841.841 ◽

1994 ◽

Vol 84 (3) ◽

pp. 841-846 ◽

Cited By ~ 37

Author(s):

MR Silva ◽

R Hoffman ◽

EF Srour ◽

JL Ascensao

Keyword(s):

Nk Cells ◽

Natural Killer ◽

Mononuclear Cells ◽

Viral Infections ◽

Nk Cell ◽

Interleukin 2 ◽

Peripheral Blood Mononuclear ◽

Specific Lysis ◽

Human Natural Killer Cells

Abstract Human natural killer (NK) cells comprise 10% to 15% of peripheral blood mononuclear cells and have an important role in immune responses against tumors, viral infections, and graft rejection. NK cells originate in bone marrow (BM), but their progenitors and lineage development have not been completely characterized. We studied the generation of NK cells from purified CD34+HLADR- and CD34+HLADR+ BM progenitors and the influence of various cytokines on their production. We show that CD3-CD56+ cytotoxic NK cells can develop from both progenitors populations when interleukin-2 (IL-2) is present in an in vitro suspension culture system containing IL-1 alpha and stem cell factor. Up to 83.8% and 98.6% CD3-CD56+ cells were detected in CD34+HLADR- and CD34+DR+ cultures, respectively, after 5 weeks of culture; significant numbers of NK cells were first detected after 2 weeks. Cytotoxic activity paralleled NK cell numbers; up to 70% specific lysis at an effector:target ratio of 10:1 was observed at 5 weeks. IL-7 also triggered development of CD3-CD56+ cells from these immature progenitors (up to 24% and 55% appeared in CD34+HLADR- and CD34+HLADR+ cultures, respectively). Our data suggest that BM stromas are not necessary for NK cell development and that IL-2 remains essential for this lineage development and differentiation.

Download Full-text

Slaying the Trojan Horse: Natural Killer Cells Exhibit Robust Anti-HIV-1 Antibody-Dependent Activation and Cytolysis against Allogeneic T Cells

Journal of Virology ◽

10.1128/jvi.02461-14 ◽

2014 ◽

Vol 89 (1) ◽

pp. 97-109 ◽

Cited By ~ 31

Author(s):

Shayarana L. Gooneratne ◽

Jonathan Richard ◽

Wen Shi Lee ◽

Andrés Finzi ◽

Stephen J. Kent ◽

...

Keyword(s):

T Cells ◽

Nk Cells ◽

Natural Killer ◽

Nk Cell ◽

Target Cells ◽

Dependent Manner ◽

Inhibitory Receptors ◽

Cell Responses ◽

Anti Hiv ◽

Hiv 1

ABSTRACTMany attempts to design prophylactic human immunodeficiency virus type 1 (HIV-1) vaccines have focused on the induction of neutralizing antibodies (Abs) that block infection by free virions. Despite the focus on viral particles, virus-infected cells, which can be found within mucosal secretions, are more infectious than free virus bothin vitroandin vivo. Furthermore, assessment of human transmission couples suggests infected seminal lymphocytes might be responsible for a proportion of HIV-1 transmissions. Although vaccines that induce neutralizing Abs are sought, only some broadly neutralizing Abs efficiently block cell-to-cell transmission of HIV-1. As HIV-1 vaccines need to elicit immune responses capable of controlling both free and cell-associated virus, we evaluated the potential of natural killer (NK) cells to respond in an Ab-dependent manner to allogeneic T cells bearing HIV-1 antigens. This study presents data measuring Ab-dependent anti-HIV-1 NK cell responses to primary and transformed allogeneic T-cell targets. We found that NK cells are robustly activated in an anti-HIV-1 Ab-dependent manner against allogeneic targets and that tested target cells are subject to Ab-dependent cytolysis. Furthermore, the educated KIR3DL1+NK cell subset from HLA-Bw4+individuals exhibits an activation advantage over the KIR3DL1−subset that contains both NK cells educated through other receptor/ligand combinations and uneducated NK cells. These results are intriguing and important for understanding the regulation of Ab-dependent NK cell responses and are potentially valuable for designing Ab-dependent therapies and/or vaccines.IMPORTANCENK cell-mediated anti-HIV-1 antibody-dependent functions have been associated with protection from infection and disease progression; however, their role in protecting from infection with allogeneic cells infected with HIV-1 is unknown. We found that HIV-1-specific ADCC antibodies bound to allogeneic cells infected with HIV-1 or coated with HIV-1 gp120 were capable of activating NK cells and/or trigging cytolysis of the allogeneic target cells. This suggests ADCC may be able to assist in preventing infection with cell-associated HIV-1. In order to fully utilize NK cell-mediated Ab-dependent effector functions, it might also be important that educated NK cells, which hold the highest activation potential, can become activated against targets bearing HIV-1 antigens and expressing the ligands for self-inhibitory receptors. Here, we show that with Ab-dependent stimulation, NK cells expressing inhibitory receptors can mediate robust activation against targets expressing the ligands for those receptors.

Download Full-text

Dysregulation of Natural Killer Cells in Obesity

Cancers ◽

10.3390/cancers11040573 ◽

2019 ◽

Vol 11 (4) ◽

pp. 573 ◽

Cited By ~ 15

Author(s):

Donal O’Shea ◽

Andrew E. Hogan

Keyword(s):

Nk Cells ◽

Natural Killer ◽

Cell Biology ◽

Viral Infections ◽

Nk Cell ◽

Viral Immunity ◽

Host Protection ◽

Cell Functions ◽

Innate Lymphocytes ◽

The Impact

Natural killer (NK) cells are a population of lymphocytes which classically form part of the innate immune system. They are defined as innate lymphocytes, due to their ability to kill infected or transformed cells without prior activation. In addition to their cytotoxic abilities, NK cells are also rapid producers of inflammatory cytokines such as interferon gamma (IFN-γ) and are therefore a critical component of early immune responses. Due to these unique abilities, NK cells are a very important component of host protection, especially anti-tumour and anti-viral immunity. Obesity is a worldwide epidemic, with over 600 million adults and 124 million children now classified as obese. It is well established that individuals who are obese are at a higher risk of many acute and chronic conditions, including cancer and viral infections. Over the past 10 years, many studies have investigated the impact of obesity on NK cell biology, detailing systemic dysregulation of NK cell functions. More recently, several studies have investigated the role of NK cells in the homeostasis of adipose tissue and the pathophysiology of obesity. In this review, we will discuss in detail these studies and focus on emerging data detailing the metabolic mechanisms altering NK cells in obesity.

Download Full-text

Nonstochastic Coexpression of Activation Receptors on Murine Natural Killer Cells

Journal of Experimental Medicine ◽

10.1084/jem.191.8.1341 ◽

2000 ◽

Vol 191 (8) ◽

pp. 1341-1354 ◽

Cited By ~ 97

Author(s):

Hamish R.C. Smith ◽

Hubert H. Chuang ◽

Lawrence L. Wang ◽

Margarita Salcedo ◽

Jonathan W. Heusel ◽

...

Keyword(s):

Natural Killer Cells ◽

Nk Cells ◽

Natural Killer ◽

Nk Cell ◽

Inhibitory Receptors ◽

Antigen Receptors ◽

Killer Cells ◽

Histocompatibility Complex ◽

Nk Cell Cytotoxicity

Murine natural killer cells (NK) express lectin-like activation and inhibitory receptors, including the CD94/NKG2 family of receptors that bind Qa-1, and the Ly-49 family that recognizes major histocompatibility complex class I molecules. Here, we demonstrate that cross-linking of NK cells with a new specific anti–Ly-49H mAb induced NK cell cytotoxicity and cytokine production. Ly-49H is expressed on a subset of NK cells and can be coexpressed with Ly-49 inhibitory receptors. However, unlike Ly-49 inhibitory receptors, Ly-49H is not detectable on naive splenic CD3+ T cells, indicating that Ly-49H may be an NK cell–specific activation receptor. In further contrast to the stochastically expressed Ly-49 inhibitory receptors, Ly-49H is preferentially expressed with the Ly-49D activation receptor, and expression of both Ly-49H and Ly-49D is augmented on NK cells that lack receptors for Qa-1 tetramers. On developing splenic NK1.1+ cells, Ly-49D and Ly-49H are expressed later than the inhibitory receptors. These results directly demonstrate that Ly-49H activates primary NK cells, and suggest that expression of Ly-49 activation receptors by NK cells may be specifically regulated on NK cell subsets. The simultaneous expression of multiple activation receptors by individual NK cells contrasts with that of T cell antigen receptors and is relevant to the role of NK cells in innate immunity.

Download Full-text

Pluripotent Stem Cell-Derived Human Natural Killer Cells with Potent Anti-Multiple Myeloma Activity,

Blood ◽

10.1182/blood.v118.21.4034.4034 ◽

2011 ◽

Vol 118 (21) ◽

pp. 4034-4034

Author(s):

David A. Knorr ◽

Zhenya Ni ◽

Allison Bock ◽

Vijay G. Ramakrishnan ◽

Shaji Kumar ◽

...

Keyword(s):

Stem Cells ◽

Multiple Myeloma ◽

Stem Cell ◽

Nk Cells ◽

Natural Killer ◽

Tumor Cells ◽

Adoptive Immunotherapy ◽

Target Cell ◽

Peripheral Blood ◽

Nk Cell

Abstract Abstract 4034 Natural Killer (NK) cells are lymphocytes of the innate immune system with anti-viral and anti-cancer activity. Over the past decade, they have gained interest as a promising cellular source for use in adoptive immunotherapy for the treatment of cancer. Most notably, NK cells play an important role in the graft-vs-tumor effect seen in allogeneic hematopoietic stem cell transplantation (allo-HSCT), and a better understanding of NK cell biology has translated into improved transplant outcomes in acute myelogenous leukemia (AML). Small studies have demonstrated a role for NK cell activity in multiple myeloma (MM) patients receiving allo-HSCT. Investigators have also utilized haplo-identical killer immunoglobulin-like receptor (KIR) mismatched NK cells for adoptive immunotherapy in patients with multiple myeloma (MM). Our group has focused on the development of NK cells from human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) as a novel starting source of lymphocytes for immunotherapy. We have previously demonstrated potent anti-tumor activity of hESC-derived NK cells in vitro and in vivo against a variety of different targets. We have also shown that iPSC-derived NK cells from a variety of different somatic cell starting sources posses potent anti-tumor and anti-viral activity. Here, we demonstrate hESC- and iPSC-derived NK cell development in a completely defined, feeder-free system that is amenable to clinical scale-up. These cultures contain a pure population of mature NK cells devoid of any T or B cell contamination, which are common adverse bystanders of cellular products isolated and enriched from peripheral blood. Our cultures are homogenous for their expression of CD56 and express high levels of effector molecules known to be important in anti-MM activity, including KIR, CD16, NKG2D, NKp46, NKp44, FasL and TRAIL. We have now tested the activity of hESC- and iPSC-derived NK cells against MM tumor cells in order to provide a universal source of lymphocytes for adoptive immunotherapy in patients with treatment refractory disease. We find that similar to peripheral blood NK cells (PB-NK), hESC- and iPSC-derived NK cells are cytotoxic against 3 distinct MM cell lines in a standard chromium release cytotoxicity assay. Specifically, activated PB-NK cells killed 48.5% of targets at 10 to 1 effector to target ratios, whereas hESC (46.3%) and iPSC (42.4%) derived NK cells also demonstrated significant anti-MM activity. Also, hESC- and iPSC-derived NK cells secrete cytokines (IFNγ and TNFα) and degranulate as demonstrated by CD107a surface expression in response to MM target cell stimulation. When tested against freshly isolated samples from MM patients, hESC- and IPSC-derived NK cells respond at a similar level as activated PB-NK cells, the current source of NK cells used in adoptive immunotherapy trials. These MM targets (both cell lines and primary tumor cells) are known to express defined ligands (MICA/B, DR4/5, ULBP-1, BAT3) for receptors expressed on NK cells as well as a number of undefined ligands for natural cytotoxicity receptors (NCRs) and KIR. As these receptor-ligand interactions drive the anti-MM activity of NK cells, we are currently evaluating expression of each of these molecules on the surface of both the effector and target cell populations. Not only do hESC- and iPSC-derived NK cells provide a unique, homogenous cell population to study these interactions, they also provide a genetically tractable source of lymphocytes for improvement of the graft-vs-myeloma effect and could be tailored on a patient specific basis using banks of hESC-or iPSC-derived NK cells with defined KIR genotypes for use as allogeneic or autologous effector cells. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

DC-like cell-dependent activation of human natural killer cells by the bisphosphonate zoledronic acid is regulated by γδ T lymphocytes

Blood ◽

10.1182/blood-2011-01-328526 ◽

2011 ◽

Vol 118 (10) ◽

pp. 2743-2751 ◽

Cited By ~ 53

Author(s):

Oliver Nussbaumer ◽

Georg Gruenbacher ◽

Hubert Gander ◽

Martin Thurnher

Keyword(s):

T Cell ◽

Zoledronic Acid ◽

T Lymphocytes ◽

Nk Cells ◽

Natural Killer ◽

Cell Activation ◽

Nk Cell ◽

Γδ T Cell ◽

Caspase 1 ◽

Ifn Γ

Abstract Bisphosphonates are mainly used for the inhibition of osteoclast-mediated bone resorption but also have been shown to induce γδ T-cell activation. Using IL-2–primed cultures of CD56+ peripheral blood mononuclear cells, we show here that zoledronic acid (zoledronate) could induce IFN-γ production not only in γδ T lymphocytes but, surprisingly, also in natural killer (NK) cells in a manner that depended on antigen-presenting cells, which share properties of inflammatory monocytes and dendritic cells (DCs; here referred to as DC-like cells). In the presence of γδ T lymphocytes, DC-like cells were rapidly eliminated, and NK cell IFN-γ production was silenced. Conversely, in the absence of γδ T lymphocytes, DC-like cells were spared, allowing NK cell IFN-γ production to proceed. γδ T cell–independent NK cell activation in response to zoledronate was because of downstream depletion of endogenous prenyl pyrophosphates and subsequent caspase-1 activation in DC-like cells, which then provide mature IL-18 and IL-1β for the activation of IL-2–primed NK cells. Pharmacologic inhibition of caspase-1 almost abolished IFN-γ production in NK cells and γδ T lymphocytes, indicating that caspase-1–mediated cytokine maturation is the crucial mechanism underlying innate lymphocyte activation in response to zoledronate.

Download Full-text

An improved method to produce clinical scale natural killer cells from human pluripotent stem cells

10.1101/614792 ◽

2019 ◽

Author(s):

Huang Zhu ◽

Dan S. Kaufman

Keyword(s):

Stem Cells ◽

Nk Cells ◽

Natural Killer ◽

Pluripotent Stem Cells ◽

Nk Cell ◽

Embryonic Stem ◽

Human Pluripotent Stem Cells ◽

Genetically Engineered ◽

Cell Populations ◽

Clinical Scale

AbstractHuman natural killer (NK) cell-based adoptive anti-cancer immunotherapy has gained intense interest with many clinical trials actively recruiting patients to treat a variety of both hematological malignancies and solid tumors. Most of these trials use primary NK cells isolated either from peripheral blood (PB-NK cells) or umbilical cord blood (UCB-NK cells), though these sources require NK cell collection for each patient leading to donor variability and heterogeneity in the NK cell populations. In contrast, NK cells derived human embryonic stem cells (hESC-NK cells) or induced pluripotent stem cells (hiPSC-NK cells) provide more homogeneous cell populations that can be grown at clinical scale, and genetically engineered if desired. These characteristics make hESC/iPSC-derived NK cells an ideal cell population for developing standardized, “off-the-shelf” immunotherapy products. Additionally, production of NK cells from undifferentiated human pluripotent stem cells enables studies to better define pathways that regulate human NK cell development and function. Our group previously established a stromal-free, two-stage culture system to derive NK cells from hESC/hiPSC in vitro followed by clinical-scale expansion of these cells using interleukin-21 expressing artificial antigen-presenting cells. However, prior to differentiation, this method requires single cell adaption of hESCs/hiPSCs which takes months. Recently we optimized this method by adapting the mouse embryonic fibroblast-dependent hESC/hiPSC to feeder-free culture conditions. These feeder-free hESC/hiPSCs are directly used to generate hemato-endothelial precursor cells. This new method produces mature, functional NK cells with higher efficiency to enable rapid production of an essentially unlimited number of homogenous NK cells that can be used for standardized, targeted immunotherapy for the treatment of refractory cancers and infectious diseases.

Download Full-text