Generation of transmitochondrial cybrids using a microfluidic device.

Mitochondrial cloning is a promising approach to achieve homoplasmic mitochondrial DNA (mtDNA) mutations. We previously developed a microfluidic device that performs single mitochondrion transfer from a mtDNA-intact cell to a mtDNA-less (ρ0) cell by promoting cytoplasmic connection through a microtunnel between them. In the present study, we described a method for generating transmitochondrial cybrids using the microfluidic device. After achieving mitochondrial transfer between HeLa cells and thymidine kinase-deficient ρ0143B cells using the microfluidic device, selective culture was carried out using a pyruvate and uridine (PU)-absent and 5-bromo-2'-deoxyuridine-supplemented culture medium. The resulting cells contained HeLa mtDNA and 143B nuclei, but both 143B mtDNA and HeLa nuclei were absent in these cells. Additionally, these cells showed lower lactate production than parent ρ0143B cells and disappearance of PU auxotrophy for cell growth. These results suggest successful generation of transmitochondrial cybrids using the microfluidic device. Furthermore, we succeeded in selective harvest of generated transmitochondrial cybrids under a PU-supplemented condition by removing unfused ρ0 cells with puromycin-based selection in the microfluidic device.

Eicosapentaenoic acid suppresses cisplatin-induced muscle atrophy by attenuating the up-regulated gene expression of ubiquitin.

Previously it was shown that cisplatin causes muscle atrophy. Under this condition, cisplatin increased the expression of atorogenes, such as muscle ring finger 1 and atrogin-1 (also known as muscle atrophy F-box protein), in mouse skeletal muscle. It was reported recently that ubiquitin (Ub) and ubiquitinated protein levels in skeletal muscle were also up-regulated in cisplatin-induced muscle atrophy, and cisplatin-induced ubiquitinated proteins were degraded by the 26S proteasome pathway. Eicosapentaenoic acid (EPA) is effective against skeletal muscle atrophy in mice. However, it is unclear how EPA suppresses the Ub-proteasome pathway. In this study, the effect of EPA on cisplatin-induced muscle atrophy in mice was examined. Mice were intraperitoneally injected with cisplatin or vehicle control once daily for 4 d. EPA or its vehicle was orally administered 30 min before cisplatin administration. Cisplatin systemic administration induced decrease in muscle mass, myofiber diameter, and increase in Ub genes and ubiquitinated proteins in mouse skeletal muscle were recovered by co-treatment with EPA. However, weight loss and up-regulated atrogenes induced by cisplatin were not changed by co-treatment with EPA in skeletal muscle. In this study, EPA attenuated cisplatin-induced muscle atrophy via down-regulation of up-regulated Ub gene expression. Although further clinical studies are needed, EPA administration can be effective in the development of muscle atrophy in cisplatin-treated patients.

Fc-Binding Antibody-Recruiting Molecules Targeting Prostate-Specific Membrane Antigen: Defucosylation of Antibody for Efficacy Improvement*.

Synthetic small molecules that redirect endogenous antibodies to target cells are promising drug candidates because they overcome the potential shortcomings of therapeutic antibodies, such as immunogenicity and the need for intravenous delivery. Previously, we reported a novel class of bispecific molecules targeting the antibody Fc region and folate receptor, named Fc-binding antibody-recruiting molecules (Fc-ARMs). Fc-ARMs can theoretically recruit most endogenous antibodies, inducing antibody-dependent cell-mediated cytotoxicity (ADCC) to eliminate cancer cells. Herein, we describe new Fc-ARMs that target prostate cancer (Fc-ARM-Ps). Fc-ARM-Ps recruited antibodies to cancer cells expressing prostate-specific membrane antigen but did so with lower efficiency compared with Fc-ARMs targeting the folate receptor. Upon recruitment by Fc-ARM-P, defucosylated antibodies efficiently activated natural killer cells and induced ADCC, whereas antibodies with intact N-glycans did not. The results suggest that the affinity between recruited antibodies and CD16a, a type of Fc receptor expressed on immune cells, could be a key factor controlling immune activation in the Fc-ARM strategy.

Highly Activated Ex Vivo-expanded Natural Killer Cells in Patients With Solid Tumors in a Phase I/IIa Clinical Study.

BACKGROUND: We previously developed a novel technique for expanding highly activated and purified natural killer (NK) cells able to maximize the theoretical activation potential of NK cells; thus, we named this cell population zenithal-NK (ZNK). AIM: To evaluate the safety, feasibility, and preliminary efficacy of autologous ZNK cells in patients with different types of advanced cancer with measurable solid lesions. PATIENTS AND METHODS: In this phase I/IIb first-in-human, open-label, dose-escalation study (trial registration ID: UMIN-000011555), eligible patients received ZNK cells intravenously starting from 106 to 108 cells/patient/dose at 2-week dosing intervals. A maximum of six cycles were allowed. Safety and survival analyses were also carried out for cases that were excluded and never administered ZNK cells. RESULTS: As of April 20, 2017, a total of nine patients were enrolled in this study, with one recruited twice. Overall, neither grade 2 or higher toxicities (Common Terminology Criteria for Adverse Events v5.0) caused by cell administration, nor adverse events causing discontinuation of protocol treatment were found. In four cases, the number of administered ZNK cells was increased to 108 cells/body/dose without any serious dose-limiting toxicity; the maximally tolerated dose was therefore considered to be at least 108 cells. The overall response rate was 40.0% in 10 net cases, one of partial response and three of stable disease, and the patient with partial response is still alive after 4 year's observation. CONCLUSION: These results demonstrate that autologous ZNK cells are safe and well-tolerated in patients with different types of advanced solid tumors. Clinical studies using similarly active ZNK cells from human leukocyte antigen/killer cell immunoglobulin-like receptor-mismatched healthy donors under Good Manufacturing Practice-compliant manufacturing, and with modified treatment regimen, i.e. doses and frequencies, are warranted for further investigation to show the potential of ZNK cells in such patients.

Increased Rac1 Activation in the Enhanced Carbachol-Induced Bronchial Smooth Muscle Contraction of Repeatedly Antigen-Challenged Mice.

Recently, we demonstrated that Rac1 upregulation is involved in augmented bronchial smooth muscle (BSM) contractions of antigen-challenged mice. However, change in G protein-coupled receptor (GPCR)-induced Rac1 activation remains unknown in BSMs of repeatedly antigen-challenged (Chal.) mice. We here examined carbachol (CCh)-induced Rac1 activation in BSMs of Chal. mice. Gene expression levels of both Rac1 and Rac-guanine nucleotide exchange factors (GEFs), such as Tiam1 and Trio, were increased in BSMs of Chal. mice. Furthermore, CCh-induced Rac1 activation was inhibited by pretreatment with Rac1-GEF inhibitor NSC23766 and Rac1 inhibitor EHT1864 in BSMs of sensitized-control (S.C.) and Chal. mice. Compared with S.C. mice, CCh-induced Rac1 activation was increased in BSMs of Chal. mice. In conclusion, we reported that increased CCh-induced Rac1 activation via Tiam1 and Trio upregulation, in addition to upregulate Rac1, may be involved in increased CCh-induced BSM contractions in Chal. mice.

Bif-1/Endophilin B1/SH3GLB1 regulates bone homeostasis.

Skeletal tissue homeostasis is maintained via the balance of osteoclastic bone resorption and osteoblastic bone formation. Autophagy and apoptosis are essential for the maintenance of homeostasis and normal development in cells and tissues. We found that Bax-interacting factor 1 (Bif-1/Endophillin B1/SH3GLB1), involving in autophagy and apoptosis, was upregulated during osteoclastogenesis. Furthermore, mature osteoclasts expressed Bif-1 in the cytosol, particularly the perinuclear regions and podosome, suggesting that Bif-1 regulates osteoclastic bone resorption. Bif-1-deficient (Bif-1 -/- ) mice showed increased trabecular bone volume and trabecular number. Histological analyses indicated that the osteoclast numbers increased in Bif-1 -/- mice. Consistent with the in vivo results, osteoclastogenesis induced by receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL) was accelerated in Bif-1 -/- mice without affecting RANKL-induced activation of RANK downstream signals, such as NF-κB and mitogen-activated protein kinases (MAPKs), CD115/RANK expression in osteoclast precursors, osteoclastic bone-resorbing activity and the survival rate. Unexpectedly, both the bone formation rate and osteoblast surface substantially increased in Bif-1 -/- mice. Treatment with ß-glycerophosphate (ß-GP) and ascorbic acid (A.A) enhanced osteoblastic differentiation and mineralization in Bif-1 -/- mice. Finally, bone marrow cells from Bif-1 -/- mice showed a significantly higher colony-forming efficacy by the treatment with or without ß-GP and A.A than cells from wild-type (WT) mice, suggesting that cells from Bif-1 -/- mice had higher clonogenicity and self-renewal activity than those from WT mice. In summary, Bif-1 might regulate bone homeostasis by controlling the differentiation and function of both osteoclasts and osteoblasts (235 words).

Up-regulation of Rac1 in the bronchial smooth muscle of murine experimental asthma.

There has been considerable research on the involvement of RhoA/Rho kinase signalling in smooth muscle contractions. However, only a few reports have addressed the specific role of Rac1, which is a member of the Rho GTPase superfamily. Therefore, this study investigated the role of Rac1-related pathways in bronchial smooth muscle (BSM) contractions. Bronchial rings isolated from mice were suspended in an organ bath, and the isometric contractions of circular smooth muscles were monitored. The phosphorylation of myosin light chains (MLCs) was analysed by immunoblotting. The Rac1 inhibitor EHT1864 inhibited carbachol (CCh)-induced BSM contractions, although high K+ depolarization-induced BSM contractions were not significantly attenuated by EHT1864. Moreover, high K+ - and phorbol 12,13-dibutyrate (PDBu; PKC activator)-induced contractions were not attenuated by Rac1 inhibition, whereas sodium fluoride (NaF)-induced force development was inhibited by EHT1864. The gene and protein expression of Rac1 was increased in the BSM of a murine model with antigen-induced airway hyper-responsiveness (AHR). In addition, an increased force of the BSM contractions in AHR was suppressed by EHT1864 treatment, suggesting that the up-regulation of Rac1 is involved in AHR. These findings suggest that an increase in Rac1-mediated signalling is involved in the augmented contractions of BSMs in antigen-induced AHR mice.

miR-3148 Is a Novel Onco-microRNA that Potentiates Tumor Growth In Vivo.

BACKGROUND/AIM: Alterations of microRNA expression in three-dimensional spheroids were examined to identify novel microRNAs that might be associated with tumorigenesis. MATERIALS AND METHODS: Using microRNA microarray analysis, we screened for microRNAs that were dramatically up-regulated inside three-dimensional spheroids in genetically-modified HCT116 human colon cancer cells expressing Copepoda Green Fluorescent Protein under hypoxia. RESULTS: miR-3148 was identified as a possible candidate onco-microRNA. A growth advantage of HCT116 cells stably expressing miR-3148 (HCT116-miR3148) was observed compared to parental cells in vivo, but not in vitro. Additionally, no change in growth under hypoxic or starvation conditions was seen in these cells cultured two-dimensionally; however, HCT116-miR3148 cells maintained as three-dimensional spheroids were highly resistant to hypoxic conditions. HCT116-miR3148 cells were more sensitive to mitogen-activated protein kinase (MAPK) kinase inhibitors and extracellular signal-regulated kinase (ERK) inhibitors. CONCLUSION: MiR-3148 may be a novel onco-microRNA that protects cancer cells from serious stress conditions through the MAPK/ERK pathway, especially in vivo.

Natural antibody against neuroblastoma of TH-MYCN transgenic mice does not correlate with spontaneous regression.

The mechanism underlying the spontaneous regression of neuroblastoma is unclear. Although it was hypothesized that this regression occurs via an immunological mechanism, there is no clinical evidence, and no animal models have been developed to investigate the involvement of immune systems, especially natural antibodies, against neuroblastoma. We performed an immunological analysis of homo- and heterozygous TH-MYCN transgenic mice as a model of aggressive neuroblastoma. Mice with no or small (<5 mm) tumors showed higher antibody titers in plasma than mice with large (>5 mm) tumors. A significant negative correlation was observed between the tumor diameter and the titer of antitumor antibody. This antibody had complement-dependent cytotoxicity but not antibody-dependent cellular cytotoxicity against neuroblastoma cells. Moreover, B-cell depletion had no effect on the tumor incidence in vivo. We revealed that TH-MYCN transgenic mice have a natural antibody against neuroblastoma that correlate with tumor size. However, this antibody does not correlate with the spontaneous regression of neuroblastoma. Thus, the function of the natural antibody is limited.

Capecitabine reverses tumor escape from anti-VEGF through the eliminating CD11bhigh/Gr1high myeloid cells.

The anti-VEGF humanized antibody bevacizumab suppresses various malignancies, but tumors can acquire drug resistance. Preclinical studies suggest myeloid-derived suppressor cells (MDSCs) may be associated with tumor refractoriness to anti-VEGF treatment. Here we report a novel mechanism of tumor escape from anti-VEGF therapy. Anti-VEGF treatment enhanced intratumoral recruitment of CD11bhigh/Gr-1high polymorphonuclear (PMN)-MDSCs in anti-VEGF-resistant Lewis lung carcinoma tumors. This effect was diminished by the anticancer agent capecitabine, a pro-drug converted to 5-fluorouracil, but not by 5-fluorouracil itself. This process was mediated by enhanced intratumoral granulocyte-colony stimulating factor expression, as previously demonstrated. However, neither interleukin-17 nor Bv8, which were previously identified as key contributors to anti-VEGF resistance, was involved in this model. Capecitabine eliminated PyNPase-expressing MDSCs from both tumors and peripheral blood. Capecitabine treatment also reversed inhibition of both antitumor angiogenesis and tumor growth under anti-VEGF antibody treatment, and this effect partially inhibited in tumors implanted in mice deficient in both PyNPases. These results indicate that intratumoral granulocyte-colony stimulating factor expression and CD11bhigh/Gr-1high PMN-MDSC recruitment underlie tumor resistance to anti-VEGF therapy, and suggest PyNPases are potentially useful targets during anti-angiogenic therapy.

Phospholipase C-related, but catalytically inactive protein (PRIP) up-regulates osteoclast differentiation via calcium-calcineurin-NFATc1 signaling.

Phospholipase C-related, but catalytically inactive protein (PRIP) was previously identified as a novel inositol 1,4,5-trisphosphate-binding protein with a domain organization similar to that of phospholipase C-δ but lacking phospholipase activity. We recently showed that PRIP gene knock-out (KO) in mice increases bone formation and concomitantly decreases bone resorption, resulting in increased bone mineral density and trabecular bone volume. However, the role of PRIP in osteoclastogenesis has not yet been fully elucidated. Here, we investigated the effects of PRIP on bone remodeling by investigating dynamic tooth movement in mice fitted with orthodontic devices. Morphological analysis indicated that the extent of tooth movement was smaller in the PRIP-KO mice than in wild-type mice. Histological analysis revealed fewer osteoclasts on the bone-resorption side in maxillary bones of PRIP-KO mice, and osteoclast formation assays and flow cytometry indicated lower osteoclast differentiation in bone marrow cells isolated from these mice. The expression of genes implicated in bone resorption was lower in differentiated PRIP-KO cells, and genes involved in osteoclast differentiation, such as the transcription factor NFATc1, exhibited lower expression in immature PRIP-KO cells initiated by M-CSF. Moreover, calcineurin expression and activity were also lower in the PRIP-KO cells. The PRIP-KO cells also displayed fewer M-CSF-induced changes in intracellular Ca2+ and exhibited reduced nuclear localization of NFATc1. Up-regulation of intracellular Ca2+ restored osteoclastogenesis of the PRIP-KO cells. These results indicate that PRIP deficiency impairs osteoclast differentiation, particularly at the early stages, and that PRIP stimulates osteoclast differentiation through calcium-calcineurin-NFATc1 signaling via regulating intracellular Ca2.

BubR1 Insufficiency Results in Decreased Macrophage Proliferation and Attenuated Atherogenesis in Apolipoprotein E-Deficient Mice.

BACKGROUND: Budding uninhibited by benzimidazole-related 1 (BubR1), a cell cycle-related protein, is an essential component of the spindle checkpoint that regulates cell division. BubR1 insufficiency causes early aging-associated vascular phenotypes. We generated low-BubR1-expressing mutant (BubR1L/L) and apolipoprotein E-deficient (ApoE-/-) mice (BubR1L/L-ApoE-/- mice) to investigate the effects of BubR1 on atherosclerosis. METHODS AND RESULTS: Eight-week-old male BubR1L/L-ApoE-/- mice and age-matched ApoE-/- mice were used in this study. Atherosclerotic lesion development after being fed a high-cholesterol diet for 12 weeks was inhibited in BubR1L/L-ApoE-/- mice compared with ApoE-/- mice, and was accompanied by decreased accumulation of macrophages. To address the relative contribution of BubR1 on bone marrow-derived cells compared with non-bone marrow-derived cells, we performed bone marrow transplantation in ApoE-/- and BubR1L/L-ApoE-/- mice. Decreased BubR1 in bone marrow cells and non-bone marrow-derived cells decreased the atherosclerotic burden. In vitro assays indicated that decreased BubR1 expression impaired proliferation, but not migration, of bone marrow-derived macrophages. CONCLUSIONS: BubR1 may represent a promising new target for regulating atherosclerosis.

Peritoneal Dissemination Requires an Sp1-Dependent CXCR4/CXCL12 Signaling Axis and Extracellular Matrix-Directed Spheroid Formation.

Peritonitis carcinomatosa is an advanced and intractable state of gastrointestinal and ovarian cancer, where mechanistic elucidation might enable the development of more effective therapies. Peritoneal dissemination of this type of malignancy has been generally thought to initiate from "milky spots" of primitive lymphoid tissues in the peritoneal cavity. In this study, we offer evidence challenging this idea, based on the finding that tumor implantation and directional dissemination was not required for the presence of milky spots, but rather SCF/CXCL12-expressing niche-like cells located at the border regions of perivascular adipose tissue. Interestingly, we found that peritoneal cavity lavage fluid, which specifically contains peritoneal collagen type IV and plasma fibronectin, dramatically facilitated spheroid formation of murine and human colon cancer cells. Spheroid formation strongly induced the expression of CXCR4 in an Sp1-dependent manner to promote niche-directed metastasis. Notably, disrupting sphere formation or inhibiting Sp1 activity was sufficient to suppress tumor dissemination and potentiated chemosensitivity to 5-fluorouracil. Our findings illuminate mechanisms of peritoneal cancer dissemination and highlight the Sp1/CXCR4/CXCL12 signaling axis as a rational target for the development of therapeutics to manage this intractable form of malignancy.

Effective recovery of highly purified CD326(+) tumor cells from lavage fluid of patients treated with a novel cell-free and concentrated ascites reinfusion therapy (KM-CART).

For the production of tumor-specific vaccines, including dendritic cell (DC) vaccines, the tumor cells themselves are an ideal source. Floating tumor cells in the ascites fluid from patients with malignant ascites are a good candidate source, but it is not easy to obtain pure tumor cells from ascites because of various types of cell contamination as well as protein aggregates. We here report an effective method to recover pure tumor cells from malignant ascites. We used lavage fluid from 13 patients with malignant ascites who were treated with modified cell-free and concentrated ascites reinfusion therapy (KM-CART). Cellular components were separated from the lavage fluid by centrifugation, enzymatic digestion and hemolysis. Tumor cells were purified by depleting CD45(+) leukocytes with antibody-conjugated magnetic beads. The tumor cell lysate was extracted by freeze-and-thaw cycles. The mean obtained total cell number was 7.50 × 10(7) cells (range 4.40 × 10(6)-2.48 × 10(8) cells). From this fraction, 6.39 × 10(6) (range 3.23 × 10(5)-2.53 × 10(7)) CD45(-) cells were collected, and the tumor cell purity was over 80 % defined as CD45(-)CD326(+). A sufficient amount of tumor lysate, average  = 2416 µg (range 25-8743 µg), was extracted from CD45(-)CD326(+) tumor cells. We here established an effective method to produce highly purified tumor cells from KM-CART lavage fluid. The clinical feasibility of this simple preparation method for generating tumor lysate should be examined in clinical studies of DC vaccines.

BubR1 insufficiency inhibits neointimal hyperplasia through impaired vascular smooth muscle cell proliferation in mice.

OBJECTIVE: BubR1, a cell cycle-related protein, is an essential component of the spindle checkpoint that regulates cell division. Mice with BubR1 expression reduced to 10% of the normal level display a phenotype characterized by progeria; however, the involvement of BubR1 in vascular diseases is still unknown. We generated mice in which BubR1 expression was reduced to 20% (BubR1(L/L) mice) of that in wild-type mice (BubR1(+/+)) to investigate the effects of BubR1 on arterial intimal hyperplasia. APPROACH AND RESULTS: Ten-week-old male BubR1(L/L) and age-matched wild-type littermates (BubR1(+/+)) were used in this study. The left common carotid artery was ligated, and histopathologic examinations were conducted 4 weeks later. Bone marrow transplantation was also performed. Vascular smooth muscle cells (VSMCs) were isolated from the thoracic aorta to examine cell proliferation, migration, and cell cycle progression. Severe neointimal hyperplasia was observed after artery ligation in BubR1(+/+) mice, whereas BubR1(L/L) mice displayed nearly complete inhibition of neointimal hyperplasia. Bone marrow transplantation from all donors did not affect the reconstitution of 3 hematopoietic lineages, and neointimal hyperplasia was still suppressed after bone marrow transplantation from BubR1(+/+) mice to BubR1(L/L) mice. VSMC proliferation was impaired in BubR1(L/L) mice because of delayed entry into the S phase. VSMC migration was unaffected in these BubR1(L/L) mice. p38 mitogen-activated protein kinase-inhibited VSMCs showed low expression of BubR1, and BubR1-inhibited VSMCs showed low expression of p38. CONCLUSIONS: BubR1 may represent a new target molecule for treating pathological states of vascular remodeling, such as restenosis after angioplasty.

Ex vivo generation of highly purified and activated natural killer cells from human peripheral blood.

Adoptive immunotherapy using natural killer (NK) cells has been a promising treatment for intractable malignancies; however, there remain a number of difficulties with respect to the shortage and limited anticancer potency of the effector cells. We here established a simple feeder-free method to generate purified (>90%) and highly activated NK cells from human peripheral blood-derived mononuclear cells (PBMCs). Among the several parameters, we found that CD3 depletion, high-dose interleukin (IL)-2, and use of a specific culture medium were sufficient to obtain highly purified, expanded (∼200-fold) and activated CD3(-)/CD56(+) NK cells from PBMCs, which we designated zenithal-NK (Z-NK) cells. Almost all Z-NK cells expressed the lymphocyte-activated marker CD69 and showed dramatically high expression of activation receptors (i.e., NKG2D), interferon-γ, perforin, and granzyme B. Importantly, only 2 hours of reaction at an effector/target ratio of 1:1 was sufficient to kill almost all K562 cells, and the antitumor activity was also replicated in tumor-bearing mice in vivo. Cytolysis was specific for various tumor cells, but not for normal cells, irrespective of MHC class I expression. These findings strongly indicate that Z-NK cells are purified, expanded, and near-fully activated human NK cells and warrant further investigation in a clinical setting.

BioKnife, a uPA activity-dependent oncolytic Sendai virus, eliminates pleural spread of malignant mesothelioma via simultaneous stimulation of uPA expression.

Malignant pleural mesothelioma (MPM) is highly intractable and readily spreads throughout the surface of the pleural cavity, and these cells have been shown to express urokinase-type plasminogen activator receptor (uPAR). We here examined the potential of our new and powerful recombinant Sendai virus (rSeV), which shows uPAR-specific cell-to-cell fusion activity (rSeV/dMFct14 (uPA2), named "BioKnife"), for tumor cell killing in two independent orthotopic xenograft models of human. Multicycle treatment using BioKnife resulted in the efficient rescue of these models, in association with tumor-specific fusion and apoptosis. Such an effect was also seen on both MSTO-211H and H226 cells in vitro; however, we confirmed that the latter expressed uPAR but not uPA. Of interest, infection with BioKnife strongly facilitated the uPA release from H226 cells, and this effect was completely abolished by use of either pyrrolidine dithiocarbamate (PDTC) or BioKnife expressing the C-terminus-deleted dominant negative inhibitor for retinoic acid-inducible gene-I (RIG-IC), indicating that BioKnife-dependent expression of uPA was mediated by the RIG-I/nuclear factor-κB (NF-κB) axis, detecting RNA viral genome replication. Therefore, these results suggest a proof of concept that the tumor cell-killing mechanism via BioKnife may have significant potential to treat patients with MPM that is characterized by frequent uPAR expression in a clinical setting.

Dramatic improvement of DC-based immunotherapy against various malignancies.

Dendritic cells (DCs) play a crucial role in maintaining the immune system. Though DC-based cancer immunotherapy has been suggested as a potential treatment for various kinds of malignancies, clinical efficacies are still insufficient in many human trials. To identify the causes of the low efficacies, we paid attention to their numbers and how they are activated. We proved that DCs' antitumor effect depends on their number and the way they are activated. We here established a possible breakthrough, a simple cytokine-based culture method to realize a log-scale order of functional murine/human DCs. Moreover, we demonstrated that DCs activated by replication-deficient recombinant Sendai virus (rSeV) were dramatically more effective than that seen in the use of current DC vaccine for immunotherapy against malignancies. Our study could overcome these problems and would improve treatment of malignancies.

Antagonism of VEGF by genetically engineered dendritic cells is essential to induce antitumor immunity against malignant ascites.

Malignant ascitis (MA) is a highly intractable and immunotherapy-resistant state of advanced gastrointestinal and ovarian cancers. Using a murine model of MA with CT26 colon cancer cells, we here determined that the imbalance between the VEGF-A/vascular permeability factor and its decoy receptor, soluble fms-like tryrosine kinase receptor-1 (sFLT-1), was a major cause of MA resistance to dendritic cell (DC)-based immunotherapy. We found that the ratio of VEGF-A/sFLT-1 was increased not only in murine but also in human MA, and F-gene-deleted recombinant Sendai virus (rSeV/dF)-mediated secretion of human sFLT-1 by DCs augmented not only the activity of DCs themselves, but also dramatically improved the survival of tumor-bearing animals associated with enhanced CTL activity and its infiltration to peritoneal tumors. These findings were not seen in immunodeficient mice, indicating that a VEGF-A/sFLT-1 imbalance is critical for determining the antitumor immune response by DC-vaccination therapy against MA.

Cytokine-based high log-scale expansion of functional human dendritic cells from cord-blood CD34-positive cells.

Dendritic cells (DCs) play a crucial role in maintaining the immune system. Though DC-based cancer immunotherapy has been suggested as a potential treatment for various kinds of malignancies, its clinical efficacies are still insufficient in many human trials. Issues that limit the clinical efficacy of DC-based immunotherapy, as well as the difficulty of the industrial production of DCs, are largely due to the limited number of autologous DCs available from each patient. We here established a possible breakthrough, a simple cytokine-based culture method to expand the log-scale order of functional human DCs. Floating cultivation of cord-blood CD34(+) cells under an optimized cytokine cocktail led these progenitor cells to stable log-scale proliferation and to DC differentiation. The expanded DCs had typical features of conventional myeloid DCs in vitro. Therefore, the concept of DC expansion should contribute significantly to the progress of DC immunotherapy.