Ex vivo expansion of CD3depleted cord blood-MNCs in the presence of bone marrow stromal cells; an appropriate strategy to provide functional NK cells applicable for cellular therapy

In vitro differentiation of human CD45+ CD34+ induced hematopoietic progenitor cells from iPSCs using a monolayer system

Hematopoietic stem cells (HSCs) represent crucial target cells in the management of hematopoietic and immune system disorders. Unfortunately, the primary source of hematopoietic stem cells is limited. Hematopoietic stem cells derived from induced pluripotent stem cells (iPSCs) hold great promise for applications in cell therapy, disease modeling, and drug screening. To achieve a consistent induction method, one specific induction scheme capable of reliably generating CD34 and CD45 double-positive cells from iPSCs was optimized, employing a comparative analysis and screening of various induction methods. The comprehensive induction procedures are outlined in this document.

Mitochondrial mass of circulating NK cells as a novel biomarker in severe SARS-CoV-2 infection

BACKGROUND

Severe SARS-CoV-2 infection results in lymphopenia and impaired function of T, B, and NK (TBNK-dominant) lymphocytes. Mitochondria are essential targets of SARS-CoV-2 and the efficacy of lymphocyte mitochondrial function for immunosurveillance in COVID-19 patients has not been evaluated.

METHODS

Multi-parametric flow cytometry was used to characterize mitochondrial function, including mitochondrial mass (MM) and low mitochondrial membrane potential (MMPlow), in TBNK-dominant lymphocytes from severe (n = 93) and moderate (n = 77) hospitalized COVID-19 patients. We compared the role of novel lymphocyte mitochondrial indicators and routine infection biomarkers as early predictors of severity and death in COVID-19 patients. We then developed a mortality decision tree prediction model based on immunosurveillance indicators through machine learning.

RESULTS

At admission, the MM of circulating NK cells (NK-MM) was the best discriminator of severe/moderate disease (AUC = 0.8067) compared with the routine infection biomarkers. The NK cell count and NK-MM displayed superior diagnostic effects to distinguish patients with non-fatal or fatal outcomes. Interestingly, NK-MM was significantly polarized in non-survivors, with some patients showing a decrease and others showing an abnormal increase. Kaplan-Meier analysis showed that NK-MM had the optimal predictive efficacy (hazard ratio = 11.66). The decision tree model has the highest proportion of importance for NK-MM, which is superior to the single diagnostic effect of the above indicators (AUC = 0.8900).

CONCLUSION

NK-MM was not only associated with disease severity, its abnormal increases or decreases also predicted mortality risk. The resulting decision tree prediction model is the first to focus on immune monitoring indicators to provide decision-making clues for COVID-19 clinical management.

Immunotherapeutic potential of blinatumomab-secreting γ9δ2 T Cells

Previous studies have explored the use of engineered blinatumomab-secreting autologous αβ T cells for CD19-targeted cancer therapy. To create a more flexible allogeneic delivery system, we utilized γ9δ2 T cells rather than αβ T cells in a similar application. First, we showed that γ9δ2 T cells could serve as effector cells for blinatumomab, and these effector memory cells could survive for at least 7 days after infusion. The genetically modified blinatumomab-secreting γ9δ2 T cells induced significant cytotoxicity in CD19⁺ tumor cell lines and primary cells from chronic lymphocytic leukemia patients. Of note, blinatumomab-secreting γ9δ2 T cells might also exhibit dual-targeting of CD19 and isopentenyl pyrophosphate, a universal tumor-associated antigen. Furthermore, blinatumomab-secreting γ9δ2 T cells killed CD19-transfected adherent cells, suggesting that the γ9δ2 T cells might be effective for treating solid tumors with appropriate cancer antigens. Together, these results demonstrate the promise of blinatumomab-secreting γ9δ2 T cells as a cancer therapy.

Natural Killer Cells in SARS-CoV-2 Infection: Pathophysiology and Therapeutic Implications

Natural Killer (NK) cells are lymphocytes of the innate immunity that play a crucial role in the control of viral infections in the absence of a prior antigen sensitization. Indeed, they display rapid effector functions against target cells with the capability of direct cell killing and antibody-dependent cell-mediated cytotoxicity. Furthermore, NK cells are endowed with immune-modulatory functions innate and adaptive immune responses via the secretion of chemokines/cytokines and by undertaking synergic crosstalks with other innate immune cells, including monocyte/macrophages, dendritic cells and neutrophils. Recently, the Coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread globally. Although the specific role of NK cells in COVID-19 pathophysiology still need to be explored, mounting evidence indicates that NK cell tissue distribution and effector functions could be affected by SARS-CoV-2 infection and that a prompt NK cell response could determine a good clinical outcome in COVID-19 patients. In this review, we give a comprehensive overview of how SARS-CoV-2 infection interferes with NK cell antiviral effectiveness and their crosstalk with other innate immune cells. We also provide a detailed characterization of the specific NK cell subsets in relation to COVID-19 patient severity generated from publicly available single cell RNA sequencing datasets. Finally, we summarize the possible NK cell-based therapeutic approaches against SARS-CoV-2 infection and the ongoing clinical trials updated at the time of submission of this review. We will also discuss how a deep understanding of NK cell responses could open new possibilities for the treatment and prevention of SARS-CoV-2 infection.

Advances in NK cell production

Immunotherapy based on natural killer (NK) cells is a promising approach for treating a variety of cancers. Unlike T cells, NK cells recognize target cells via a major histocompatibility complex (MHC)-independent mechanism and, without being sensitized, kill the cells directly. Several strategies for obtaining large quantities of NK cells with high purity and high cytotoxicity have been developed. These strategies include the use of cytokine-antibody fusions, feeder cells or membrane particles to stimulate the proliferation of NK cells and enhance their cytotoxicity. Various materials, including peripheral blood mononuclear cells (PBMCs), umbilical cord blood (UCB), induced pluripotent stem cells (iPSCs) and NK cell lines, have been used as sources to generate NK cells for immunotherapy. Moreover, genetic modification technologies to improve the proliferation of NK cells have also been developed to enhance the functions of NK cells. Here, we summarize the recent advances in expansion strategies with or without genetic manipulation of NK cells derived from various cellular sources. We also discuss the closed, automated and GMP-controlled large-scale expansion systems used for NK cells and possible future NK cell-based immunotherapy products.

Mesenchymal stem cells and natural killer cells interaction mechanisms and potential clinical applications

Natural killer cells (NK cells) are innate immune cells that are activated to fight tumor cells and virus-infected cells. NK cells also play an important role in the graft versus leukemia response. However, they can over-develop inflammatory reactions by secreting inflammatory cytokines and increasing Th1 differentiation, eventually leading to tissue damage. Today, researchers have attributed some autoimmune diseases and GVHD to NK cells. On the other hand, it has been shown that mesenchymal stem cells (MSCs) can modulate the activity of NK cells, while some researchers have shown that NK cells can cause MSCs to lysis. Therefore, we considered it is necessary to investigate the effect of these two cells and their signaling pathway in contact with each other, also their clinical applications.

Exhausted NK cells and cytokine storms in COVID-19: Whether NK cell therapy could be a therapeutic choice

The global outbreak of coronavirus-2019 (COVID-19) still claims more lives daily around the world due to the lack of a definitive treatment and the rapid tendency of virus to mutate, which even jeopardizes vaccination efficacy. At the forefront battle against SARS-CoV-2, an effective innate response to the infection has a pivotal role in the initial control and treatment of disease. However, SARS-CoV-2 subtly interrupts the equations of immune responses, disrupting the cytolytic antiviral effects of NK cells, while seriously activating infected macrophages and other immune cells to induce an unleashed "cytokine storm", a dangerous and uncontrollable inflammatory response causing life-threatening symptoms in patients. Notably, the NK cell exhaustion with ineffective cytolytic function against the sources of exaggerated cytokine release, acts as an Achilles' heel which exacerbates the severity of COVID-19. Given this, approaches that improve NK cell cytotoxicity may benefit treatment protocols. As a suggestion, adoptive transfer of NK or CAR-NK cells with proper cytotolytic potentials and the lowest capacity of cytokine-release (for example CD56^dim NK cells brightly express activating receptors), to severe COVID-19 patients may provide an effective cure especially in cases suffering from cytokine storms. More intriguingly, the ongoing evidence for persistent clonal expansion of NK memory cells characterized by an activating phenotype in response to viral infections, can benefit the future studies on vaccine development and adoptive NK cell therapy in COVID-19. Whether vaccinated volunteers or recovered patients can also be considered as suitable candidates for cell donation could be the subject of future research.

Overcoming the UCB HSCs -Derived NK cells Dysfunction through Harnessing RAS/MAPK, IGF-1R and TGF-β Signaling Pathways

Background

The natural killer (NK) cells differentiated from umbilical cord blood (UCB) hematopoietic stem cells (HSCs) may be more suitable for cell-based immunotherapy compared to the NK cells from adult donors. This is due to the possibility to choose alloreactive donors and potentially more robust in vivo expansion. However, the cytotoxicity of UCB-HSC-derived NK cells against cancer cells might be suboptimal. To overcome this obstacle, we attempted to generate NK cells with potent antitumor activity by targeting RAS/MAPK, IGF-1R and TGF-β signaling pathways using IL-15, IGF-1 and SIS3 respectively.

Methods

The CD34 + cells were isolated from human UCB mononuclear cells through magnetic activation cell sorting (MACS) with purity of (≥ 90%) and were subjected to differentiate into NK cells. After 21 days of induction with SFTG36 (SCF, FLt-3L, TPO, GM-CSF, IL-3 and IL-6), IS721 (IGF-1, SIS3, IL-7 and IL-21) and IL-15/Hsp70 media, NK cells phenotypes were studied and their cytotoxicity against K562 human erythroleukemia cells and SKOV3 ovarian carcinoma cells was analyzed.

Results

The NK cells induced in SFTG36/IS721 medium were selected for activation due to their higher expression of CD56 + 16 + CD3 −  (93.23% ± 0.75) and mean fluorescence intensity (MFI) of NKG2D + (168.66 ± 20.00) and also a higher fold expansion potential (11.893 ± 1.712) compared to the other groups. These cells once activated with IL-15, demonstrated a higher cytotoxicity against K562 (≥ 90%; P ≤ 0.001) and SKOV3 tumor cells (≥ 65%; P ≤ 0.001) compared to IL-15/Hsp70-activated NK cells.

Conclusions

The differentiation of ex vivo expanded CD34 + cells through manipulation of RAS/MAPK, IGF-1R and TGF-β signaling pathways is an efficient approach for generating functional NK cells that can be used for cancer immunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01983-z.

Optimizing the Procedure to Manufacture Clinical-Grade NK Cells for Adoptive Immunotherapy

Simple Summary

Natural Killer cells have shown promise to treat different malignancies. Several methods have been described to obtain fully activated NK cells for clinical use. Here, we use different cell culture media and different artificial antigen presenting cells to optimize a GMP compliant manufacturing method to obtain activated and expanded NK cells suitable for clinical use.

Abstract

Natural killer (NK) cells represent promising tools for cancer immunotherapy. We report the optimization of an NK cell activation–expansion process and its validation on clinical-scale. Methods: RPMI-1640, stem cell growth medium (SCGM), NK MACS and TexMACS were used as culture mediums. Activated and expanded NK cells (NKAE) were obtained by coculturing total peripheral blood mononuclear cells (PBMC) or CD45RA⁺ cells with irradiated K562mbIL15-41BBL or K562mbIL21-41BBL. Fold increase, NK cell purity, activation status, cytotoxicity and transcriptome profile were analyzed. Clinical-grade NKAE cells were manufactured in CliniMACS Prodigy. Results: NK MACS and TexMACs achieved the highest NK cell purity and lowest T cell contamination. Obtaining NKAE cells from CD45RA⁺ cells was feasible although PBMC yielded higher total cell numbers and NK cell purity than CD45RA⁺ cells. The highest fold expansion and NK purity were achieved by using PBMC and K562mbIL21-41BBL cells. However, no differences in activation and cytotoxicity were found when using either NK cell source or activating cell line. Transcriptome profile showed to be different between basal NK cells and NKAE cells expanded with K562mbIL21-41BBL or K562mbIL15-41BBL. Clinical-grade manufactured NKAE cells complied with the specifications from the Spanish Regulatory Agency. Conclusions: GMP-grade NK cells for clinical use can be obtained by using different starting cells and aAPC.

A simple method for in vitro preparation of natural killer cells from cord blood

Background

Cord Blood (CB) has been considered a promising source of natural killer (NK) cells for cellular immunotherapy. However, it is difficult to expand the large numbers of highly pure NK cells from CB without cell sorting and feeder cells/multiple cytokines. In this study, we try to develop a simple, safe and economical method for ex vivo expansion and purification of NK cells from CB without cell sorting and feeder cells/multiple cytokines.

Results

The large numbers (mean: 1.59 × 10¹⁰) of highly pure (≥90%) NK cells from CB could be obtained through interleukin-2, group A streptococcus and zoledronate stimulation of mononuclear cells using the 21-day culture approach. When compared to resting NK cells, expanded NK cells were a higher expression of activating receptors CD16, NKG2D, NKp30, NKp44, NKp46 and activating markers CD62L and CD69, while the inhibitory receptors, CD158a and CD158b remained largely unchanged. In addition, these cells showed a higher concentration of IFN-γ, TNF-α and GM-CSF secretion and cytotoxicity to K562 cells and acute myeloid leukemia targets than resting NK cells.

Conclusion

We develop a simple, safe and economical method to obtain high yield, purity, and functionality NK cells from CB without cell sorting and feeder cells/multiple cytokines.

The early expansion of anergic NKG2Apos/CD56dim/CD16neg natural killer represents a therapeutic target in haploidentical hematopoietic stem cell transplantation

Natural killer cells are the first lymphocyte population to reconstitute early after non-myeloablative and T cell-replete haploidentical hematopoietic stem cell transplantation with post-transplant infusion of cyclophosphamide. The study herein characterizes the transient and predominant expansion starting from the second week following haploidentical hematopoietic stem cell transplantation of a donor-derived unconventional subset of NKp46^neg-low/CD56^dim/CD16^neg natural killer cells expressing remarkably high levels of CD94/NKG2A. Both transcription and phenotypic profiles indicated that unconventional NKp46^neg-low/CD56^dim/CD16^neg cells are a distinct natural killer cell subpopulation with features of late stage differentiation, yet retaining proliferative capability and functional plasticity to generate conventional NKp46^pos/CD56^bright/CD16^neg-low cells in response to interleukin-15 plus interleukin-18. While present at low frequency in healthy donors, unconventional NKp46^neg-low/CD56^dim/CD16^neg cells are greatly expanded in the seven weeks following haploidentical hematopoietic stem cell transplantation, and express high levels of the activating receptors NKG2D and NKp30 as well as of the lytic granules Granzyme-B and Perforin. Nonetheless, NKp46^neg-low/CD56^dim/CD16^neg cells displayed a markedly defective cytotoxicity that could be reversed by blocking the inhibitory receptor CD94/NKG2A. These data open new and important perspectives to better understand the ontogenesis/homeostasis of human natural killer cells and to develop a novel immune-therapeutic approach that targets the inhibitory NKG2A check-point, thus unleashing natural killer cell alloreactivity early after haploidentical hematopoietic stem cell transplantation.

Comparable osteogenic capacity of mesenchymal stem or stromal cells derived from human amnion membrane and bone marrow

So far, substantial attentions have been attracted to the application of mesenchymal stem or stromal cells (MSCs) in different therapeutic approaches. Although human bone marrow is commonly considered as a major source for MSCs, having an invasive collection method, ethical consideration and donor availability create a challenge for scientists, leading them to explore better alternative sources for MSCs. The study presented here aimed to characterize and compare osteogenic capacity of MSCs obtained from the amnion membrane (AM) with those originated from BM. Cells isolated from AMs and BMs were cultured in DMEM-low glucose supplemented with FBS, penicillin and streptomycin. After 24 h of incubation, cells adhered to the plastic surface of the flasks were allowed to proliferate for more days. A sub-confluent culture of cells was trypsinized and re-cultured. The MSCs were characterized by the expression of specific markers with flow cytometry. The osteogenic differentiation of MSCs was also validated by alkaline phosphatase and alizarian red S staining. Our results showed comparable expression of MSCs specific markers for both MSC sources (AM and BM). We also showed the optimum osteogenic differentiation of MSCs from both sources whereas hAM-MSCs revealed higher proliferation rate. We found no essential immunophenotypic differences between MSCs originated from bone marrow and amnion membrane while their differentiations into osteoblastic linage were also comparable. This was in addition to the higher proliferation rate observed for hAM-MSCs which suggests hAM as an easily accessible and reliable source of MSCs applicable for bone engineering, regenerative medicine or other therapeutic approaches.