Differential effects of autologous serum on CD34(+) or monocyte-derived dendritic cells

Thapsigargin-Stimulated LAD2 Human Mast Cell Line Is a Potent Cellular Adjuvant for the Maturation of Monocyte-Derived Dendritic Cells for Adoptive Cellular Immunotherapy

The preparation of dendritic cells (DCs) for adoptive cellular immunotherapy (ACI) requires the maturation of ex vivo-produced immature(i) DCs. This maturation ensures that the antigen presentation triggers an immune response towards the antigen-expressing cells. Although there is a large number of maturation agents capable of inducing strong DC maturation, there is still only a very limited number of these agents approved for use in the production of DCs for ACI. In seeking novel DC maturation agents, we used differentially activated human mast cell (MC) line LAD2 as a cellular adjuvant to elicit or modulate the maturation of ex vivo-produced monocyte-derived iDCs. We found that co-culture of iDCs with differentially activated LAD2 MCs in serum-containing media significantly modulated polyinosinic:polycytidylic acid (poly I:C)-elicited DC maturation as determined through the surface expression of the maturation markers CD80, CD83, CD86, and human leukocyte antigen(HLA)-DR. Once iDCs were generated in serum-free conditions, they became refractory to the maturation with poly I:C, and the LAD2 MC modulatory potential was minimized. However, the maturation-refractory phenotype of the serum-free generated iDCs was largely overcome by co-culture with thapsigargin-stimulated LAD2 MCs. Our data suggest that differentially stimulated mast cells could be novel and highly potent cellular adjuvants for the maturation of DCs for ACI.

In-Depth Analysis of the Impact of Different Serum-Free Media on the Production of Clinical Grade Dendritic Cells for Cancer Immunotherapy

Dendritic cell (DC)-based antitumor vaccines have proven to be a safe approach, but often fail to generate robust results between trials. Translation to the clinic has been hindered in part by the lack of standard operation procedures for vaccines production, namely the definition of optimal culture conditions during ex-vivo DC differentiation. Here we sought to compare the ability of three clinical grade serum-free media, DendriMACS, AIM-V, and X-VIVO 15, alongside with fetal bovine serum-supplemented Roswell Park Memorial Institute Medium (RPMI), to support the differentiation of monocyte-derived DCs (Mo-DCs). Under these different culture conditions, phenotype, cell metabolomic profiles, response to maturation stimuli, cytokines production, allogenic T cell stimulatory capacity, as well as priming of antigen-specific CD8⁺ T cells and activation of autologous natural killer (NK) cells were analyzed. Immature Mo-DCs differentiated in AIM-V or X-VIVO 15 presented lower levels of CD1c, CD1a, and higher expression of CD11c, when compared to cells obtained with DendriMACS. Upon stimulation, only AIM-V or X-VIVO 15 DCs acquired a full mature phenotype, which supports their enhanced capacity to polarize T helper cell type 1 subset, to prime antigen-specific CD8⁺ T cells and to activate NK cells. CD8⁺ T cells and NK cells resulting from co-culture with AIM-V or X-VIVO 15 DCs also showed superior cytolytic activity. 1H nuclear magnetic resonance-based metabolomic analysis revealed that superior DC immunostimulatory capacities correlate with an enhanced catabolism of amino acids and glucose. Overall, our data highlight the impact of critically defining the culture medium used in the production of DCs for clinical application in cancer immunotherapy. Moreover, the manipulation of metabolic state during differentiation could be envisaged as a strategy to enhance desired cell characteristics.

Equine dendritic cells generated with horse serum have enhanced functionality in comparison to dendritic cells generated with fetal bovine serum

Background

Dendritic cells are professional antigen-presenting cells that play an essential role in the initiation and modulation of T cell responses. They have been studied widely for their potential clinical applications, but for clinical use to be successful, alternatives to xenogeneic substances like fetal bovine serum (FBS) in cell culture need to be found. Protocols for the generation of dendritic cells ex vivo from monocytes are well established for several species, including horses. Currently, the gold standard protocol for generating dendritic cells from monocytes across various species relies upon a combination of GM-CSF and IL-4 added to cell culture medium which is supplemented with FBS. The aim of this study was to substitute FBS with heterologous horse serum. For this purpose, equine monocyte-derived dendritic cells (eqMoDC) were generated in the presence of horse serum or FBS and analysed for the effect on morphology, phenotype and immunological properties. Changes in the expression of phenotypic markers (CD14, CD86, CD206) were assessed during dendritic cell maturation by flow cytometry. To obtain a more complete picture of the eqMoDC differentiation and assess possible differences between FBS- and horse serum-driven cultures, a transcriptomic microarray analysis was performed. Lastly, immature eqMoDC were primed with a primary antigen (ovalbumin) or a recall antigen (tetanus toxoid) and, after maturation, were co-cultured with freshly isolated autologous CD5⁺ T lymphocytes to assess their T cell stimulatory capacity.

Results

The microarray analysis demonstrated that eqMoDC generated with horse serum were indistinguishable from those generated with FBS. However, eqMoDC incubated with horse serum-supplemented medium exhibited a more characteristic dendritic cell morphology during differentiation from monocytes. A significant increase in cell viability was also observed in eqMoDC cultured with horse serum. Furthermore, eqMoDC generated in the presence of horse serum were found to be superior in their functional T lymphocyte priming capacity and to elicit significantly less non-specific proliferation.

Conclusions

EqMoDC generated with horse serum-supplemented medium showed improved morphological characteristics, higher cell viability and exhibited a more robust performance in the functional T cell assays. Therefore, horse serum was found to be superior to FBS for generating equine monocyte-derived dendritic cells.

Comparison of media and serum supplementation for generation of monophosphoryl lipid A/interferon-γ-matured type I dendritic cells for immunotherapy

BACKGROUND AIMS

Ex vivo-generated monocyte-derived dendritic cells (DCs) matured with monophosphoryl lipid A (MPLA) and interferon-γ (IFN-γ) can be used as cancer immunotherapy. MPLA/IFN-γ DCs induce Th1 T cell responses and have migratory capacity. Different culture regimens have been used for generation of immunotherapeutic DCs, with varying results. In the present study, culture conditions for MPLA/IFN-γ-matured type I DCs were optimized for clinical application.

METHODS

DCs were generated from monocytes in the clinical grade culture media CellGro DC, AIM V or X-VIVO 15 in the absence or presence of 2% human serum (HS) and matured with the use of MPLA/IFN-γ. DC yield and DC functionality were assessed. DC functionality was determined by means of analysis of cytokines in culture supernatant, migratory capacity, expression of co-stimulatory molecules, T cell stimulatory capacity of DCs and T helper cell (Th) polarization by the DCs.

RESULTS

DCs generated in the presence of 2% HS produced low amounts of pro-inflammatory cytokines and could not migrate irrespective of the medium used. In the absence of HS, MPLA/IFN-γ DCs generated in X-VIVO did not migrate either. MPLA/IFN-γ DCs generated in AIM V have slightly lower capacity to induce Th1 cells than do DCs generated in CellGro or X-VIVO.

CONCLUSIONS

Addition of HS to different GMP culture media is detrimental for pro-inflammatory DC maturation and migration. In the absence of serum, CellGro is the most optimal medium tested for generation of migratory and Th1-inducing MPLA/IFN-γ DCs for cancer immunotherapy.

Day-4 myeloid dendritic cells pulsed with whole tumor lysate are highly immunogenic and elicit potent anti-tumor responses

“Day-7” myeloid DCs are commonly used in the clinic. However, there is a strong need to develop DCs faster that have the same potent immunostimulatory capacity as “Day-7” myeloid DCs and at the same time minimizing time, labor and cost of DC preparations. Although “2 days” DCs can elicit peptide-specific responses, they have not been demonstrated to engulf, process and present complex whole tumor lysates, which could be more convenient and personalized source of tumor antigens than defined peptides. In this preclinical study, we evaluated the T-cell stimulatory capacity of Day-2, Day-4, and Day-7 cultured monocyte-derived DCs loaded with SKOV3 cell whole lysate prepared by freeze-thaw or by UVB-irradiation followed by freeze-thaw, and matured with lipopolysaccharide (LPS) and interferon (IFN)-gamma. DCs were evaluated for antigen uptake, and following maturation with LPS and IFN-gamma, DCs were assessed for expression of CD80, CD40, CD86, ICAM-1 and CCR7, production of IL-12p70 and IP-10, and induction of tumor-specific T-cell responses. Day-4 and Day-7 DCs exhibited similar phagocytic abilities, which were superior to Day-2 DCs. Mature Day-7 DCs expressed the highest CD40 and ICAM-1, but mature Day-4 DCs produced the most IL-12p70 and IP-10. Importantly, Day-4 and Day-7 DCs derived from ovarian cancer patients stimulated equally strongly tumor-specific T-cell responses. This is the first study demonstrating the highly immunogenic and strong T-cell stimulatory properties of Day-4 myeloid DCs, and provided important preclinical data for rapid development of potent whole tumor lysate-loaded DC vaccines that are applicable to many tumor types.

Optimizing parameters for clinical-scale production of high IL-12 secreting dendritic cells pulsed with oxidized whole tumor cell lysate

BACKGROUND

Dendritic cells (DCs) are the most potent antigen-presenting cell population for activating tumor-specific T cells. Due to the wide range of methods for generating DCs, there is no common protocol or defined set of criteria to validate the immunogenicity and function of DC vaccines.

METHODS

Monocyte-derived DCs were generated during 4 days of culture with recombinant granulocyte-macrophage colony stimulating factor and interleukin-4, and pulsed with tumor lysate produced by hypochlorous acid oxidation of tumor cells. Different culture parameters for clinical-scale DC preparation were investigated, including: 1) culture media; 2) culture surface; 3) duration of activating DCs with lipopolysaccharide (LPS) and interferon (IFN)-gamma; 4) method of DC harvest; and 5) cryomedia and final DC product formulation.

RESULTS

DCs cultured in CellGenix DC media containing 2% human AB serum expressed higher levels of maturation markers following lysate-loading and maturation compared to culturing with serum-free CellGenix DC media or AIM-V media, or 2% AB serum supplemented AIM-V media. Nunclon™Δ surface, but not Corning(®) tissue-culture treated surface and Corning(®) ultra-low attachment surface, were suitable for generating an optimal DC phenotype. Recombinant trypsin resulted in reduced major histocompatibility complex (MHC) Class I and II expression on mature lysate-loaded DCs, however presentation of MHC Class I peptides by DCs was not impaired and cell viability was higher compared to cell scraping. Preservation of DCs with an infusible cryomedia containing Plasma-Lyte A, dextrose, sodium chloride injection, human serum albumin, and DMSO yielded higher cell viability compared to using human AB serum containing 10% DMSO. Finally, activating DCs for 16 hours with LPS and IFN-γ stimulated robust mixed leukocyte reactions (MLRs), and high IL-12p70 production in vitro that continued for 24 hours after the cryopreserved DCs were thawed and replated in fresh media.

CONCLUSIONS

This study examined criteria including DC phenotype, viability, IL-12p70 production and the ability to stimulate MLR as metrics of whole oxidized tumor lysate-pulsed DC immunogenicity and functionality. Development and optimization of this unique method is now being tested in a clinical trial of autologous oxidized tumor lysate-pulsed DC in clinical-scale in recurrent ovarian, primary peritoneal or fallopian tube cancer (NCT01132014).

Modification of human embryonic stem cell-derived dendritic cells with mRNA for efficient antigen presentation and enhanced potency

AIM

Dendritic cell (DC)-based vaccines are designed to exploit the intrinsic capacity of these highly effective antigen presenting cells to prime and boost antigen-specific T-cell immune responses. Successful development of DC-based vaccines will be dependent on the ability to utilize and harness the full potential of these potent immune stimulatory cells. Recent advances to generate DCs derived from human embryonic stem cells (hESCs) that are suitable for clinical use represent an alternative strategy from conventional approaches of using patient-specific DCs. Although the differentiation of hESC-derived DCs in serum-free defined conditions has been established, the stimulatory potential of these hESC-derived DCs have not been fully evaluated.

METHODS

hESC-derived DCs were differentiated in serum-free defined culture conditions. The delivery of antigen into hESC-derived DCs was investigated using mRNA transfection and replication-deficient adenoviral vector transduction. hESC-derived DCs modified with antigen were evaluated for their capacity to stimulate antigen-specific T-cell responses with known HLA matching. Since IL-12 is a key cytokine that drives T-cell function, further enhancement of DC potency was evaluated by transfecting mRNA encoding the IL-12p70 protein into hESC-derived DCs.

RESULTS

The transfection of mRNA into hESC-derived DCs was effective for heterologous protein expression. The efficiency of adenoviral vector transduction into hESC-derived DCs was poor. These mRNA-transfected DCs were capable of stimulating human telomerase reverse transcriptase antigen-specific T cells composed of varying degrees of HLA matching. In addition, we observed the transfection of mRNA encoding IL-12p70 enhanced the T-cell stimulation potency of hESC-derived DCs.

CONCLUSION

These data provide support for the development and modification of hESC-derived DCs with mRNA as a potential strategy for the induction of T-cell-mediated immunity.

Exogenous control of the expression of Group I CD1 molecules competent for presentation of microbial nonpeptide antigens to human T lymphocytes

Group I CD1 (CD1a, CD1b, and CD1c) glycoproteins expressed on immature and mature dendritic cells present nonpeptide antigens (i.e., lipid or glycolipid molecules mainly of microbial origin) to T cells. Cytotoxic CD1-restricted T lymphocytes recognizing mycobacterial lipid antigens were found in tuberculosis patients. However, thanks to a complex interplay between mycobacteria and CD1 system, M. tuberculosis possesses a successful tactic based, at least in part, on CD1 downregulation to evade CD1-dependent immunity. On the ground of these findings, it is reasonable to hypothesize that modulation of CD1 protein expression by chemical, biological, or infectious agents could influence host's immune reactivity against M. tuberculosis-associated lipids, possibly affecting antitubercular resistance. This scenario prompted us to perform a detailed analysis of the literature concerning the effect of external agents on Group I CD1 expression in order to obtain valuable information on the possible strategies to be adopted for driving properly CD1-dependent immune functions in human pathology and in particular, in human tuberculosis.

A Comparative Analysis of Serum and Serum-free Media for Generation of Clinical Grade DCs

Dendritic cells (DCs) are the most potent antigen presenting cells and are therefore widely used in cancer immunotherapy. An optimal method for the generation of DCs for clinical use remains to be established. The aim of the study was to find a serum-free media (SFM) able to generate reproducible and functional cultures of DCs for clinical studies. We characterized immature and mature DCs cultured in SFM, CellGro DC and X-VIVO15, and serum media (SM), RPMI 1640+5% human serum or autologous serum. The expression of HLA-DR, CD86, CD83 was higher in SM-cultured DCs (SM-DCs) than SFM-derived DCs (SFM-DCs). Between SFM-DCs, CellGro-cultured DCs (CellGro-DCs) showed a higher expression and an improved up-regulation capacity of all molecules as compared with X-VIVO15-derived DCs (X-VIVO15-DCs). CellGro-DCs and SM-DCs showed a similar mannose receptor expression and related endocytic capacity tested by fluorescein isothiocyanate-dextran uptake. In contrast X-VIVO15-DCs expressed low levels of mannose receptor and were unable to endocyte fluorescein isothiocyanate-dextran. DCs cultured in all conditions stimulated a mix lymphocyte reaction, but CellGro-DCs and SM-DCs induced a more potent T-cell proliferation compared with X-VIVO15-DCs. Cytokine analysis showed that after maturation, all DC cultures produced IL-12p70 and IL-10 except for X-VIVO15-DCs which only produced the latter cytokine. SM-DCs and SFM-DCs induced a TH1 polarization in allogeneic naive T cells. In conclusion, a comparative analysis of DC performance generated in different conditions allows us to determine CellGro DC as the optimal medium for the generation of clinical grade DCs.

Clinical effects of autologous dendritic cells combined with anti-virus therapy on chronic hepatitis B virus infection

AIM: To evaluate the clinical effects of autologous HBsAg-loaded dendritic cells (DCs) combined with anti-viral treatment on patients with chronic hepatitis B virus (HBV) infection.

METHODS: A total of 41 chronic HBV infected subjects were treated with single interferon-α-2b for 6 mo before the trial, and the treatment was stopped for the irresponsive cases. Six months later, the irresponsive cases received the combined therapy of interferon-α-2b and autologous HBsAg-loaded DCs for another 6 mo (one course containing twice of re-transfusion). The changes of virology, serology and biochemistry indexes were observed one month after the end of treatment.

RESULTS: DCs were cultured in vitro. After proliferation for 6 d, DCs were incubated with HBsAg for 1 d to prepare the specific DCs vaccine. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significant decreased after the combined therapy as compared with those before (t = 2.976, P < 0.01; t = 2.049, P < 0.05). The response rate of HBV DNA was 53.7%, and the decrease of HBV DNA copies was greater than or equal to 2log10. Neither the injection times of DCs nor the HBV-carrying time had a correlation with the virological responses (r = 0.048, P > 0.05; r = 0.137, P > 0.05).

CONCLUSION: Combined treatment of autologous DCs vaccine and interferon-α-2b has a favorable effect on patients with chronic HBV infection.

Molecular aspects of microparticle phagocytosis by dendritic cells

The ability of immature dendritic cells (iDCs) derived from human peripheral blood mononuclear cells to phagocytose poly(lactic-co-glycolic acid) (PLGA) microparticles (MPs) as compared to polystyrene MPs and the molecular aspects of this phagocytosis were investigated. Treating iDCs with PLGA or polystyrene fluorospheres of approximately 3 microm in diameter resulted in the internalization of the particles as evidenced by confocal laser scanning micrographs. This uptake of fluorospheres by DCs was decreased by pretreatment of cells with cytochalasin D or by incubation with the fluorospheres at 4 degrees C, and was sensitive to EDTA and trypsin pretreatments in a dose-dependent manner. In agreement with our previous studies, treatment of iDCs with PLGA MPs, but not with polystyrene MPs, led to DC maturation, as measured by increase in release of the autocrine maturation cytokine, tumor necrosis factor-alpha, which was dependent on ratio of PLGA MPs to DCs. Taken together, this work begins to address the role of phagocytosis on PLGA MP-induced DC maturation and the molecular mechanisms involved.

Effects of mesenchymal stem cells on differentiation, maturation, and function of human monocyte-derived dendritic cells

Mesenchymal stem cells (MSCs) reportedly inhibit the mixed lymphocyte reaction. Whether this effect is mediated by dendritic cells (DCs) is still unknown. In this study, we used an in vitro model to observe the effects of MSCs and their supernatants on the development of monocyte-derived DCs. Phenotypes and the endocytosic ability of harvested DCs were determined by flow cytometry; interleukin 12 (IL-12) secreted by DCs was evaluated by enzyme-linked immunosorbent assay (ELISA); and the antigen-presenting function of DCs was evaluated by MLR. Our results show that MSCs inhibit the up-regulation of CD1a, CD40, CD80, CD86, and HLA-DR during DC differentiation and prevent an increase of CD40, CD86, and CD83 expression during DC maturation. MSCs supernatants had no effect on DCs differentiation, but they inhibited the up-regulation of CD83 during maturation. Both MSCs and their supernatants interfered with endocytosis of DCs, decreased their capacity to secret IL-12 and activate alloreactive T cells. Thus, effects of MSCs on DCs contribute to immunoregulation and development.

Leukemia-Derived Dendritic Cells can be Generated from Blood or Bone Marrow Cells from Patients with Acute Myeloid Leukaemia: A Methodological Approach under Serum-Free Culture Conditions

Functional dendritic cells (DC) are professional antigen-presenting cells (APC) and can be generated in vitro from healthy as well as from leukaemic cells from acute myeloid leukemia (AML) patients giving rise to APC of leukaemic origin-presenting leukaemic antigens. We describe the generation and characterization of DC from different mononuclear cell (MNC) fractions from 50 AML patients under different serum-free culture conditions, determine the optimal culture conditions and compare the results with that from 23 healthy donors. In parallel cultures, we compared DC harvests after 7- or 14-day culture, with total or adherent MNC or T-cell depleted MNC or peripheral blood (PB) or bone marrow-MNC (BM-MNC), thawn or fresh MNC, in Xvivo or CellGro serum-free media, +/-10% autologous plasma or +/-FL. In detail, we could show that AML-DC harvests were higher after 10-14 days culture (healthy DC: 7 days); total or adherent PB or BM-MNC fractions yield comparable DC counts, however, from magnetic cell sorting (MACS)-depleted MNC fractions or thawn MNC lower DC counts can be generated. Whereas the addition of FL increases the DC harvest, the addition of autologous plasma in many cases has inhibitory influence on DC maturation. CellGro and Xvivo media yield comparable DC counts. Optimal harvest of vital and mature DC from AML samples was obtained with a granulocyte/macrophage-colony stimulating factor, interleukin-4, FL and tumour necrosis factor-alpha-containing serum-free Xvivo medium after 10-14 days of culture (36/26% DC; 38/64% vital DC; 46/51% mature DC were generated from AML/healthy MNC samples). Surface marker profiles (e.g. costimulatory antigen expressing) of DC obtained from AML samples were comparable with that of healthy DC. The leukaemic derivation of AML-DC was demonstrated by the persistence of the clonal cytogenetic aberration in the DC or by coexpression of leukaemic antigens on DC. Autologous T-cell activation of leukaemia-derived DC was demonstrated in cases with AML. Autologous T cells proliferate and upregulate DC-contact-relevant antigens. We demonstrate that the generation of leukaemia-derived DC is feasable in AML under serum-free culture conditions giving rise to DC with comparable characteristics as healthy DC and offering an anti-leukaemia-directed immunotherapeutical vaccination strategy in AML.

Uptake of Apoptotic K562 Leukaemia Cells by Immature Dendritic Cells is Greatly Facilitated by Serum

Dendritic cells (DCs) are potent antigen-presenting cells and play an important role in T-cell-mediated immunity. DCs have been shown to induce strong antitumour immune responses both in vitro and in vivo. One way of providing the DCs with all relevant tumour antigens would be to incubate the DCs with material from dead tumour cells. We have examined the uptake of apoptotic and necrotic K562 leukaemia cells by DCs under different culture conditions. Results from coincubation experiments strongly suggested that uptake of apoptotic K562 cells was dependent upon the addition of autologous serum (AS). Under these conditions, 47-79% of all DCs were shown to ingest apoptotic material. AS also seemed to be important for the expression of functionally important markers, most notably HLA class I, CD86, CCR7 and CD83. The vast majority of DCs were shown to ingest necrotic material from K562 cells, with no additional effect of AS. The results suggest that incubation of DCs with apoptotic material for cell therapeutic purposes may best be performed in the presence of AS.

Clinical-scale generation of dendritic cells in a closed system

Immunotherapy of malignant diseases based on dendritic cells (DCs) pulsed with tumor antigens is a promising approach. Therefore, there is a demand for large-scale, clinical-grade ex vivo generation of DCs. Here, a procedure is presented that combines monocyte selection and tissue culture in closed systems under current good manufacturing practice conditions. Leukocytes from three patients with urologic cancers were collected by leukapheresis and subjected to immunomagnetic enrichment. From leukapheresis products containing 1.6 +/- 0.2 x 1010 (mean +/- SEM) leukocytes with a frequency of CD14+ monocytes of 18.7 +/- 2.3%, monocytes were enriched to 94.3 +/- 2.2%. CD14+ cell recovery was 67.0 +/- 4.7%. After 6 days of culture in Teflon bags in X-Vivo 15 medium supplemented with autologous plasma, GM-CSF, and IL-4, cells showed an immature DC phenotype and efficient antigen uptake. Following an additional 3 days of culture in the presence of GM-CSF, IL-4, IL-1beta, IL-6, TNFalpha, and PGE(2), cells (82.0 +/- 5.8% CD83+) displayed a mature DC morphology and phenotype, including expression of CD11b, CD11c, CD18, CD25, CD40, CD54, CD58, CD80, CD86, HLA class I, and HLA-DR as well as expression of CCR7 but not CCR5. The mature DC phenotype remained stable for at least 5 days in the absence of cytokines. Yield of DC was 14.0 +/- 4.7% and viability was 91.9 +/- 3.5%. Mature DCs effectively clustered with naive T cells and potently induced allogeneic T-cell proliferation and IL-2 and IFNgamma but not IL-4 production. Thus, this procedure allows large-scale generation of stably mature, Th1 responses inducing DCs under cGMP conditions in a closed system from cancer patients and is therefore well suited for immunotherapy.