Arc/Arg3.1 regulates an endosomal pathway essential for activity-dependent ß-amyloid generation.

Assemblies of ß-amyloid (Aß) peptides are pathological mediators of Alzheimer's Disease (AD) and are produced by the sequential cleavages of amyloid precursor protein (APP) by ß-secretase (BACE1) and γ-secretase. The generation of Aß is coupled to neuronal activity, but the molecular basis is unknown. Here, we report that the immediate early gene Arc is required for activity-dependent generation of Aß. Arc is a postsynaptic protein that recruits endophilin2/3 and dynamin to early/recycling endosomes that traffic AMPA receptors to reduce synaptic strength in both hebbian and non-hebbian forms of plasticity. The Arc-endosome also traffics APP and BACE1, and Arc physically associates with presenilin1 (PS1) to regulate γ-secretase trafficking and confer activity dependence. Genetic deletion of Arc reduces Aß load in a transgenic mouse model of AD. In concert with the finding that patients with AD can express anomalously high levels of Arc, we hypothesize that Arc participates in the pathogenesis of AD.

Characterization and abiotic stress-responsive expression analysis of SGT1 genes in Brassica oleracea.

SGT1 genes are involved in enhancing plant responses to various biotic and abiotic stresses. Brassica oleracea is known to contain two types of SGT1 genes, namely suppressor of G2 allele of SKP1 and suppressor of GCR2. In this study, through systematic analysis, four putative SGT1 genes were identified and characterized in B. oleracea. In phylogenetic analysis, the genes clearly formed separate groups, namely BolSGT1a, BolSGT1b (both suppressor of G2 allele of SKP1 types), and BolSGT1 (suppressor of GCR2). Functional domain analysis and organ-specific expression patterns suggested possible roles for BolSGT1 genes during stress conditions. BolSGT1 genes showed significant changes in expression in response to heat, cold, drought, salt, or ABA treatment. Interaction network analysis supported the expression analysis, and showed that the BolSGT1a and BolSGT1b genes are strongly associated with co-regulators during stress conditions. However, the BolSGT1 gene did not show any strong association. Hence, BolSGT1 might be a stress resistance-related gene that functions without a co-regulator. Our results show that BolSGT1 genes are potential target genes to improve B. oleracea resistance to abiotic stresses such as heat, cold, and salt.

IL-32γ induces chemotaxis of activated T cells via dendritic cell-derived CCL5.

Interleukin (IL)-32 has been associated with a variety of inflammatory diseases including rheumatoid arthritis, vasculitis and Crohn's disease. We have previously reported that IL-32γ, the IL-32 isoform with the highest biological activity, could act as an immune modulator through regulation of dendritic cell (DC) functions in immune responses. Cell locomotion is crucial for induction of an effective immune response. In this study, we investigated the effect and underlying mechanisms of IL-32γ on recruitment of T cells. IL-32γ upregulated the expression of several chemokines including CCL2, CCL4, and CCL5 in the DCs. In particular, IL-32γ significantly increased CCL5 expression in a dose-dependent manner. Treatment with JNK and NF-κB inhibitors suppressed IL-32γ-induced CCL5 expression in DCs, indicating that IL-32γ induced CCL5 production through the JNK and NF-κB pathways. Furthermore, supernatants from IL-32γ-treated DCs showed chemotactic activities controlling migration of activated CD4(+) and CD8(+) T cells, and these activities were suppressed by addition of neutralizing anti-CCL5 antibody. These results show that IL-32γ effectively promotes migration of activated T cells via CCL5 production in DCs. The chemotactic potential of IL-32γ may explain the pro-inflammatory effects of IL-32 and the pathologic role of IL-32 in immune disorders such as rheumatoid arthritis.

Adiponectin induces dendritic cell activation via PLCγ/JNK/NF-κB pathways, leading to Th1 and Th17 polarization.

Adiponectin (APN) is a crucial regulator for many inflammatory processes, but its effect on Th cell-mediated responses has not been fully understood. Thus, we investigated the immune-modulatory effects of APN on dendritic cells (DCs) controlling Th cell polarization. APN induced maturation and activation of DCs, as demonstrated by the increased expression of MHC class II, costimulatory molecules in both mouse and human DCs, and it significantly enhanced production of proinflammatory cytokines. APN triggered degradation of IκB proteins, nuclear translocation of NF-κB p65 subunit, and phosphorylation of MAPKs in DCs. Pretreatment with a phospholipase C (PLC)γ inhibitor and a JNK inhibitor suppressed IL-12 production and NF-κB binding activity. Additionally, PLCγ inhibitor downregulated phosphorylation of JNK, indicating that PLCγ and JNK may be upstream molecules of NF-κB. Importantly, APN-treated DCs significantly induced both Th1 and Th17 responses in allogeneic CD4(+) T cells. The addition of a neutralizing anti-IL-12 mAb to the cocultures abolished the secretion of IFN-γ, whereas the blockage of IL-23 and IL-1ß suppressed APN-induced IL-17 production. Immunization of mice with OVA-pulsed, APN-treated DCs efficiently led to Ag-specific Th1 and Th17 cell responses. Taken together, these results demonstrated that APN effectively induced activation of DCs through PLCγ/JNK/NF-κB-signaling pathways, leading to enhanced Th1 and Th17 responses.

Principal role of IL-12p40 in the decreased Th1 and Th17 responses driven by dendritic cells of mice lacking IL-12 and IL-18.

IL-12 and IL-18 are cytokines which are mainly secreted by endothelial cells and monocytes including dendritic cells. The well-known effects of IL-12 and IL-18 in the protection against bacteria and virus infection as well as tumor development are associated with their characteristics in synergistically driving the development of T helper type 1 (Th1) cells and inducing IFN-γ production. In this study, we compared the knockout effects of IL-12 and/or IL-18 genes on phenotypes and functional capabilities of dendritic cells (DCs) including their ability to polarize naive CD4(+) T cells. The expression levels of surface molecules such as MHC II, CD80, CD86 and ICOSL, and endocytic capacity were not significantly differences between DCs of wild type (WT) mice and double knockout (DKO) mice of IL-12p40 and IL-18. Additionally, DCs lacking IL-12p40 and/or IL-18 genes were equivalently efficient in inducing T cell proliferation, compared with the WT-DCs. Interestingly, IL-10 production significantly decreased in DKO-DCs, while production of other inflammation-related cytokines were unaffected in WT-DCs and DKO-DCs. Importantly, IL-12p40(-/-)-DCs and DKO-DCs severely impaired the ability to induce IFN-γ and IL-17 production from CD4(+) T cells. IL-18(-/-)-DCs also moderately decreased IL-17 production and IL-17-expressing CD4(+) T cells when co-cultured with CD4(+) T cells, demonstrating the involvement of IL-18 in driving IL-17 differentiation. Taken together, these results suggest the principal contribution of IL-12p40 in inducing Th1 and Th17 polarization, regardless of similar surface phenotypes of DCs.

IL-32gamma induces the maturation of dendritic cells with Th1- and Th17-polarizing ability through enhanced IL-12 and IL-6 production.

IL-32, a newly described multifunctional cytokine, has been associated with a variety of inflammatory diseases, including rheumatoid arthritis, vasculitis, and Crohn's disease. In this study, we investigated the immunomodulatory effects of IL-32γ on bone marrow-derived dendritic cell (DC)-driven Th responses and analyzed the underlying signaling events. IL-32γ-treated DCs exhibited upregulated expression of cell-surface molecules and proinflammatory cytokines associated with DC maturation and activation. In particular, IL-32γ treatment significantly increased production of IL-12 and IL-6 in DCs, which are known as Th1- and Th17-polarizing cytokines, respectively. This increased production was inhibited by the addition of specific inhibitors of the activities of phospholipase C (PLC), JNK, and NF-κB. IL-32γ treatment increased the phosphorylation of JNK and the degradation of both IκBα and IκBß in DCs, as well as NF-κB binding activity to the κB site. The PLC inhibitor suppressed NF-κB DNA binding activity and JNK phosphorylation increased by IL-32γ treatment, thereby indicating that IL-32γ induced IL-12 and IL-6 production in DCs via a PLC/JNK/NF-κB signaling pathway. Importantly, IL-32γ-stimulated DCs significantly induced both Th1 and Th17 responses when cocultured with CD4(+) T cells. The addition of a neutralizing anti-IL-12 mAb abolished the secretion of IFN-γ in a dose-dependent manner; additionally, the blockage of IL-1ß and IL-6, but not of IL-21 or IL-23p19, profoundly inhibited IL-32γ-induced IL-17 production. These results demonstrated that IL-32γ could effectively induce the maturation and activation of immature DCs, leading to enhanced Th1 and Th17 responses as the result of increased IL-12 and IL-6 production in DCs.

AIMP1 deficiency enhances airway hyperreactivity in mice via increased TH2 immune responses.

Aminoacyl tRNA synthetase complex-interacting multicomplex protein 1 (AIMP1) is known as a novel cytokine carrying out a variety of biological activities, including angiogenesis and wound repair. In our previous reports AIMP1 was demonstrated to induce TH1 polarization. However, the effects of AIMP1 deficiency in TH1 or TH2 immune disorders remain unclear. In this study, we characterized phenotypes of AIMP1-deficient mice and investigated the role of AIMP1 in TH2-biased airway hyperreactivity. Clinical signs of allergic airway inflammation were assessed in AIMP1-deficient mice and the effects of AIMP1 deficiency on production of TH2 cytokines were evaluated in T cells using AIMP1-specific siRNA. Additionally, the enhanced pause values and histologic analysis were assessed in mice receiving AIMP1-deficient CD4+ T cells with OVA challenge. Clinical signs of spontaneous airway inflammation were noted in AIMP1-deficienct mice. AIMP1-deficient mice showed strongly increased Penh values in response to methacholine without any allergen exposure. Adoptive transfer of AIMP1-deficient CD4+ T cells to OVA-sensitized C57BL/6 mice exacerbated OVA-induced airway inflammation and increased infiltration of inflammatory cells into the lung. Furthermore, lung DCs in AIMP1-deficient mice showed increased expression of surface molecules, and IL-12p40 level in sera significantly decreased in AIMP1-deficient mice compared to that of wild type mice. These results strongly indicate that AIMP1 plays a role in negatively regulating TH2 responses in vivo, and AIMP1 can be employed as a novel therapeutic agent against TH2-biased diseases, particularly asthma.

Fumarates promote cytoprotection of central nervous system cells against oxidative stress via the nuclear factor (erythroid-derived 2)-like 2 pathway.

Oxidative stress is central to the pathology of several neurodegenerative diseases, including multiple sclerosis, and therapeutics designed to enhance antioxidant potential could have clinical value. The objective of this study was to characterize the potential direct neuroprotective effects of dimethyl fumarate (DMF) and its primary metabolite monomethyl fumarate (MMF) on cellular resistance to oxidative damage in primary cultures of central nervous system (CNS) cells and further explore the dependence and function of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway in this process. Treatment of animals or primary cultures of CNS cells with DMF or MMF resulted in increased nuclear levels of active Nrf2, with subsequent up-regulation of canonical antioxidant target genes. DMF-dependent up-regulation of antioxidant genes in vivo was lost in mice lacking Nrf2 [Nrf2(-/-)]. DMF or MMF treatment increased cellular redox potential, glutathione, ATP levels, and mitochondrial membrane potential in a concentration-dependent manner. Treating astrocytes or neurons with DMF or MMF also significantly improved cell viability after toxic oxidative challenge in a concentration-dependent manner. This effect on viability was lost in cells that had eliminated or reduced Nrf2. These data suggest that DMF and MMF are cytoprotective for neurons and astrocytes against oxidative stress-induced cellular injury and loss, potentially via up-regulation of an Nrf2-dependent antioxidant response. These data also suggest DMF and MMF may function through improving mitochondrial function. The clinical utility of DMF in multiple sclerosis is being explored through phase III trials with BG-12, which is an oral therapeutic containing DMF as the active ingredient.

Cutaneous mastocytosis associated with congenital alopecia.

Mastocytosis is a rare disorder that shows accumulation of mast cells in tissues. Atypical clinical features may mimic impetigo, Langerhans cell histiocytosis, and carcinoid syndrome; however, only 1 case of scarring alopecia associated with mastocytosis has been reported. We present the first case of cutaneous mastocytosis associated with congenital alopecia areata in a 3-year-old Korean girl. This case showed an atypical clinical presentation of congenital alopecia areata, but histopathological results confirmed the diagnosis of cutaneous mastocytosis.

Suppression of dendritic cells' maturation and functions by daidzein, a phytoestrogen.

Isoflavones are ubiquitous compounds in foods and in the environment in general. Daidzein and genistein, the best known of isoflavones, are structurally similar to 17ß-estradiol and known to exert estrogenic effects. They also evidence a broad variety of biological properties, including antioxidant, anti-carcinogenic, anti-atherogenic and anti-osteoporotic activities. Previously, daidzein was reported to increase the phagocytic activity of peritoneal macrophages and splenocyte proliferation, and to inhibit nitric oxide (NO) production in macrophages. However, its potential impacts on immune response in dendritic cells (DCs), antigen-presenting cells that link innate and adaptive immunity, have yet to be clearly elucidated. In this study, we evaluated the effects of isoflavones on the maturation and activation of DCs. Isoflavones (formononetin, daidzein, equol, biochanin A, genistein) were found to differentially affect the expression of CD86, a costimulatory molecule, on lipopolysaccharide (LPS)-stimulated DCs. In particular, daidzein significantly and dose-dependently inhibited the expression levels of maturation-associated cell surface markers including CD40, costimulatory molecules (CD80, CD86), and major histocompatibility complex class II (I-A(b)) molecule on LPS-stimulated DCs. Daidzein also suppressed pro-inflammatory cytokine production such as IL-12p40, IL-6 and TNF-α, whereas it didn't affect IL-10 and IL-1ß expression. Furthermore, daidzein enhanced endocytosis and inhibited the allo-stimulatory ability of LPS-stimulated DCs on T cells, indicating that daidzein treatment can inhibit the functional maturation of DCs. These results demonstrate that daidzein may exhibit immunosuppressive activity by inhibiting the maturation and activation of DCs.

Development of a novel hyaluronic acid membrane for the treatment of ocular surface diseases.

Ocular surface diseases (OSD) can cause serious visual deterioration and discomfort. Commercial artificial tear solution containing hyaluronic acid (HA) show excellent biocompatibility and unique viscoelastic characteristics. Here, we developed a novel HA membrane (HAM) by chemical crosslinking using 1,4-butanediol diglycidyl ether for the effective treatment of OSDs. The main purpose of HAMs is to provide sustained release of HA to modulate the wound healing response in OSDs. The safety and efficacy of HAMs were investigated using primary cultured human corneal epithelial cells and various OSD rabbit models. In the dry state, the HAM is firm, transparent, and easy to manipulate. When hydrated, it swells rapidly with high water retention and over 90% transmission of visible light. Human corneal epithelial cells and rabbit eyes showed no toxic response to HAM. Addition of HAMs to the culture medium enhanced human corneal epithelial cell viability and expression of cell proliferation markers. Investigation of HAM wound healing efficacy using mechanical or chemical corneal trauma and conjunctival surgery in rabbits revealed that application of HAMs to the ocular surface enhanced healing of corneal epithelium and reduced corneal limbal vascularization, opacity and conjunctival fibrosis. The therapeutic potential of HAMs in various OSDs was successfully demonstrated.

Moxifloxacin releasing intraocular implant based on a cross-linked hyaluronic acid membrane.

Intraocular antibiotic delivery is an important technique to prevent bacterial infection after ophthalmic surgery, such as cataract surgery. Conventional drug delivery methods, such as antibiotic eye drops, have limitations for intraocular drug delivery due to the intrinsic barrier effect of the cornea. Therefore, frequent instillation of antibiotic eyedrops is necessary to reach a sufficient bactericidal concentration inside the eye. In this study, an intraocular implant, MXF-HA, that combines hyaluronic acid (HA) and moxifloxacin (MXF) was developed to increase the efficiency of intraocular drug delivery after surgery. MXF-HA is manufactured as a thin, transparent, yellow-tinted membrane. When inserted into the eye in a dry state, MXF-HA is naturally hydrated and settles in the eye, and the MXF contained therein is delivered by hydrolysis of the polymer over time. It was confirmed through in vivo experiments that MXF delivery was maintained in the anterior chamber of the eye at a concentration sufficient to inhibit Pseudomonas aeruginosa and Staphylococcus aureus for more than 5 days after implantation. These results suggest that MXF-HA can be utilized as a potential drug delivery method for the prevention and treatment of bacterial infections after ophthalmic surgery.

Resolution of disulfide heterogeneity in Nogo receptor I fusion proteins by molecular engineering.

NgRI (Nogo-66 receptor) is part of a signalling complex that inhibits axon regeneration in the central nervous system. Truncated soluble versions of NgRI have been used successfully to promote axon regeneration in animal models of spinal-cord injury, raising interest in this protein as a potential therapeutic target. The LRR (leucine-rich repeat) regions in NgRI are flanked by N- and C-terminal disulfide-containing 'cap' domains (LRRNT and LRRCT respectively). In the present work we show that, although functionally active, the NgRI(310)-Fc fusion protein contains mislinked and heterogeneous disulfide patterns in the LRRCT domain, and we report the generation of a series of variant molecules specifically designed to prevent this heterogeneity. Using these variants we explored the effects of modifying the NgRI truncation site or the spacing between the NgRI and Fc domains, or replacing cysteines within the NgRI or IgG hinge regions. One variant, which incorporates replacements of Cys²66 and Cys³°9 with alanine residues, completely eliminated disulfide scrambling while maintaining functional in vitro and in vivo efficacy. This modified NgRI-Fc molecule represents a significantly improved candidate for further pharmaceutical development, and may serve as a useful model for the optimization of other IgG fusion proteins made from LRR proteins.

Effects of Machilus thunbergii Sieb et Zucc on UV-induced photoaging in hairless mice.

Chronic ultraviolet (UV) exposure induces photoaging and oxidative stress in the skin. We investigated whether Machilus thunbergii Sieb et Zucc (M. thunbergii) could reduce UV-induced photoaging and oxidative stress in hairless mice. The dorsal skin of hairless mice was treated topically with M. thunbergii for 2 h prior to UV irradiation. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels were then measured in skin and/or serum samples. Histological changes in the skin were assessed by hematoxylin-eosin (HE) staining. In addition, proteomes from the skin of hairless mice in each group were analyzed. The thickness of the dorsal skin and epidermis was significantly decreased by M. thunbergii treatment. We also found that MDA levels decreased after M. thunbergii treatment and the SOD levels were increased by M. thunbergii compared with those in the UV-only treated group. Proteomic analysis revealed 17 proteins associated with photoaging. These data indicate that M. thunbergii might have antiphotoaging effects.

Successful Hematopoietic Stem Cell Transplantation from a Matched Related Donor with Beta-Thalassemia Minor for Severe Aplastic Anemia.

The first-line treatment for severe aplastic anemia (SAA) patients is hematopoietic stem cell transplantation (HSCT), with full-matched related donors considered the most suitable. We report a case of SAA in which the patient successfully underwent HSCT from a donor with ß-thalassemia minor. The patient in this case underwent HSCT from a human leukocyte antigen (HLA)-matched younger brother with ß-thalassemia minor. A 7-year-old girl was referred to our facility following a 6-month history of easy bruising and pallor. Laboratory examinations showed pancytopenia and hypocellular bone marrow with cellularity of <5%. She was diagnosed with acquired SAA, and HLA typing of her family members was performed. Her younger brother was an HLA-matched sibling but had ß-thalassemia minor. Since his hemoglobin levels were maintained at 10-11 d/dL, he was considered a suitable HSCT donor. The conditioning regimen included fludarabine, cyclophosphamide, and anti-thymocyte globulin. The CD34+ and CD3+ cell counts were 6.6 × 106/kg and 0.48 × 108/kg, respectively. White blood cell engraftment was evident on day +11. Regimen-associated toxicities, such as anorexia and enteritis, were mild; no infections occurred, and no symptoms of acute graft-versus-host disease (GVHD) were observed. The 30-day follow-up bone marrow examination revealed normocellular marrow with 80%-90% cellularity. Acute or chronic GVHD has not been reported, and good performance status has been observed throughout the 5 years after HSCT. ß-thalassemia minor patients can be considered as bone marrow donors for SAA patients.

Translational control by neuroguidin, a eukaryotic initiation factor 4E and CPEB binding protein.

CPEB-mediated translation is important in early development and neuronal synaptic plasticity. Here, we describe a new eukaryotic initiation factor 4E (eIF4E) binding protein, Neuroguidin (Ngd), and its interaction with CPEB. In the mammalian nervous system, Ngd is detected as puncta in axons and dendrites and in growth cones and filopodia. Ngd contains three motifs that resemble those present in eIF4G, 4EBP, Cup, and Maskin, all of which are eIF4E binding proteins. Ngd binds eIF4E directly, and all three motifs must be deleted to abrogate the interaction between these two proteins. In injected Xenopus oocytes, Ngd binds CPEB and, most importantly, represses translation in a cytoplasmic polyadenylation element (CPE)-dependent manner. In Xenopus embryos, Ngd is found in both neural tube and neural crest cells. The injection of morpholino-containing antisense oligonucleotides directed against ngd mRNA disrupts neural tube closure and neural crest migration; however, the wild-type phenotype is restored by the injection of a rescuing ngd mRNA. These data suggest that Ngd guides neural development by regulating the translation of CPE-containing mRNAs.

Analysis of the expression profiles of cytokines and cytokine-related genes during the progression of breast cancer growth in mice.

Cytokines are a protein family of regulatory factors derived from tumors and their environmental components that contribute to the growth, invasion and metastasis of breast cancer. However, the way in which tumor progression and cytokines regulate each other is not well understood. In this study, we used an oligoDNA microarray to assess the kinetic expression profile of cytokine genes in tumor tissues and lymph nodes during the progression of tumor growth in mice that had been subcutaneously challenged with breast adenocarcinoma SB5b cells. Our results demonstrated that IL-15, IL-17, IL-18 and IL-18 binding protein (IL-18bp), which are associated with inflammation, were increased in tumor tissues. Conversely, chemokines and their receptors, including CXCR4/CXCL12, CCR7/CCL21, CCL9, CXCL9 and CCL12, were overexpressed in lymph nodes during tumor growth. Furthermore, RT-PCR and Western blot analysis revealed that IL-18, a pro-angiogenic factor in tumors, was up-regulated in tumor tissues. Interestingly, CCR3, IL-1R2, SOCS and IL-20 were up-regulated in tumor tissues, but down-regulated in lymph nodes during tumor growth. This result suggests that the expression of cytokines and cytokine-related genes was differentially regulated, which resulted in a beneficial effect for tumor progression.

The ion channel activator CyPPA inhibits melanogenesis via the GSK3ß/ß-catenin pathway.

Research into materials that inhibit melanogenesis in skin has gained interest. Screening for such compounds in B16F10 cells revealed that cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA), a positive modulator of small-conductance Ca2+-activated K+ channels, is a strong inhibitor of melanogenesis. We investigated the anti-melanogenic activity of CyPPA and the molecular mechanism by which CyPPA reduced melanin production in normal human melanocytes (NHM). CyPPA treatment resulted in a significant concentration-dependent reduction in melanin content without significant cytotoxicity; treatment likewise resulted in a significant time-dependent reduction in tyrosinase (TYR) activity. Treatment with CyPPA also decreased transcription of melanogenesis-related genes, including the gene encoding microphthalmia-associated transcription factor (MITF). In addition, visual evaluation of the MelanoDerm™ human skin model revealed significantly lower melanin content in the CyPPA-treated condition than in the untreated control. CyPPA was determined to modulate glycogen synthase kinase-3ß (GSK3ß) activity, thereby leading to a decrease in ß-catenin/MITF expression. Thus, CyPPA acts as a melanogenesis inhibitor by modulating the GSK3ß/ß-catenin/MITF pathway.

Optimization of Large-Scale Expansion and Cryopreservation of Human Natural Killer Cells for Anti-Tumor Therapy.

Allogeneic natural killer (NK) cell therapy is a potential therapeutic approach for a variety of solid tumors. We established an expansion method for large-scale production of highly purified and functionally active NK cells, as well as a freezing medium for the expanded NK cells. In the present study, we assessed the effect of cryopreservation on the expanded NK cells in regards to viability, phenotype, and anti-tumor activity. NK cells were enormously expanded (about 15,000-fold expansion) with high viability and purity by stimulating CD3+ T cell-depleted peripheral blood mononuclear cells (PBMCs) with irradiated autologous PBMCs in the presence of IL-2 and OKT3 for 3 weeks. Cell viability was slightly reduced after freezing and thawing, but cytotoxicity and cytokine secretion were not significantly different. In a xenograft mouse model of hepatocellular carcinoma cells, cryopreserved NK cells had slightly lower anti-tumor efficacy than freshly expanded NK cells, but this was overcome by a 2-fold increased dose of cryopreserved NK cells. In vivo antibody-dependent cell cytotoxicity (ADCC) activity of cryopreserved NK cells was also demonstrated in a SCID mouse model injected with Raji cells with rituximab co-administration. Therefore, we demonstrated that expanded/frozen NK cells maintain viability, phenotype, and anti-tumor activity immediately after thawing, indicating that expanded/frozen NK cells can provide 'ready-to-use' cell therapy for cancer patients.