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. 2009 Aug 18;4(8):e6674.
doi: 10.1371/journal.pone.0006674.

Cytokine-based Log-Scale Expansion of Functional Murine Dendritic Cells

Free PMC article

Cytokine-based Log-Scale Expansion of Functional Murine Dendritic Cells

Yui Harada et al. PLoS One. .
Free PMC article


Background: Limitations of the clinical efficacy of dendritic cell (DC)-based immunotherapy, as well as difficulties in their industrial production, are largely related to the limited number of autologous DCs from each patient. We here established a possible breakthrough, a simple and cytokine-based culture method to realize a log-scale order of functional murine DCs (>1,000-fold), which cells were used as a model before moving to human studies.

Methodology/principal findings: Floating cultivation of lineage-negative hematopoietic progenitors from bone marrow in an optimized cytokine cocktail (FLT3-L, IL-3, IL-6, and SCF) led to a stable log-scale proliferation of these cells, and a subsequent differentiation study using IL-4/GM-CSF revealed that 3-weeks of expansion was optimal to produce CD11b+/CD11c+ DC-like cells. The expanded DCs had typical features of conventional myeloid DCs in vitro and in vivo, including identical efficacy as tumor vaccines.

Conclusions/significance: The concept of DC expansion should make a significant contribution to the progress of DC-based immunotherapy.

Conflict of interest statement

Competing Interests: Dr. Yonemitsu is a member of the Scientific Advisory Board of DNAVEC Corporation with relevant financial interest. Also, the corresponding author, YY, declares that both Drs Akihiro Iida and Mamoru Hasegawa are affiliated to DNAVEC Corporation.


Figure 1
Figure 1. Cytokine-based expansion of bone marrow-derived murine DCs.
Bone marrow (from female C3H/He)-derived lineage-negative cells (CD45R, CD5, CD11b, Gr-1, TER119, and 7/4) were enriched using a SpinSep mouse hematopoietic progenitor enrichment kit. These cells were subjected to progenitor expansion by various cytokines under a floating condition in an MPC treated flask. At each time point, the culture medium was replaced with new DC-differentiation medium (RPMI 1640 containing GM-CSF/IL-4) for 1 week. The data are expressed as the means+SEM. a. Growth curve of hematopoietic progenitor cells (HPs). Neither FLT3-L, SCF, nor IL-6 could stimulate the growth of HPs over 10 days. Only the use of IL-3 was associated with long-term growth, and this growth was greatly accelerated when a mixture of cytokines was used (FS36). Note the log scale on the HP cell number. b. FACS analyses indicating the time course of the scatter plot of HPs (left row), in populations of CD11c+CD11b+ cells at pre- and post-treatment with GM-CSF/IL-4 (middle two 2-center rows), and of the expression of c-Kit/CD131 (a receptor of GM-CSF/IL-3) and CD11c/CD11b in the R1-gated increasing population indicated in SSC/FSC (right two rows at right). These experiments were performed in triplicate, and showed similar results. c. Summary of triplicate FACS experiments representing the time course of positive cell ratios for CD11b, c-Kit, and CD131 of expanded HPs. Note the culture duration-dependent increase of c-Kit+ and CD131+ HPs. d. Bar graph indicating the relative increase of CD11b+CD11c+ DC-like cells produced after 1-week cultivation in GM-CSF/IL-4 using expanded HPs at various time points. The data was gathered from three independent experiments. Note that a period of 3 weeks was [optimal][most efficient], yielding a more than 3-log increase in the production of CD11b+CD11c+ DC-like cells.
Figure 2
Figure 2. In vitro characterization of expanded murine DCs.
a. Schematic diagram of expansion/differentiation/maturation/activation sequences and microscopic morphology of conventional and expanded DCs that were stimulated by LPS. Note that typical dendrites were found in both DCs. b. FACS analyses assessing the expression of typical surface markers. Conventional and expanded DCs after treatment with GM-CSF/IL-4 without further stimulus were subjected to FACS analyses. c. Expression of typical murine inflammatory cytokines/chemokines of conventional (open bars) and expanded (black bars) DCs in response to various stimuli for RIG-I helicase (rSeV) or Toll-like receptors (LPS for TLR-4, poly I:C for TLR-3, CpG-DNA for TLR-9, and R848 for TLR-7). The upper three panels (mIL-6, mIFN-β, and mIL-12/p70) were assessed by ELISA, and contain data from three independent experiments, and the bottom three panels (mIL-6, mMCP-1/JE, and mTNF-α) were performed using a Cytometric Bead Array (CBA) system and show one typical result taken from three independent experiments.
Figure 3
Figure 3. Assessment of functions that are typically seen in DCs.
a. FITC-dextran uptake assay assessing endo-/phagocytotic activity, a typical feature of antigen-presenting cells such as DCs. This experiment was performed in triplicate, and showed similar results. b. A graph showing MLR activity for allo-antigen (C57BL6) by iDCs or activated DCs (C3H/He) by LPS derived from the conventional technique or expansion of HPs. c. Antitumor effect of subcutaneous vaccination with rSeV/dF-activated DCs that were derived from conventional or expansion techniques. Female C3H/He mice (7-week-old) were subcutaneously vaccinated via the left flank three times each weeks with 1×106 conventional/expanded DCs pulsed with tumor lysate. Two days after the final vaccination, 1×106 LM8 cells were inoculated intradermally into the left flank of mice. Note that 3-weeks expanded HPs treated with rSeV/dF did not show any effect on tumor growth. d. Antimetastatic activity via bolus intravenous injection of various DCs. Female C3H/He mice (7-week-old) were intravenously vaccinated with 1×106 conventional/expanded DCs once via the tail vein, and 2 days later, 1×106 of LM8 cells were inoculated intravenously. Seventeen days later, mice were sacrificed and the macroscopically recognized nodules on the surface of the bilateral lungs were counted.

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