This work was supported by Program of Tianjin Science and Technology Plan (20JCQNJC00550), Tianjin Health Science and Technology Project (TJWJ202021QN033 and TJWJ202021QN034).

All procedures were approved by the Nanjing Medical University Animal Care and Use Committee.
1. Isolation of bone marrow and preparation of BM cells
<ol>
	<li>Sacrifice C57BL/6 mice (18-22 g, 6-8 weeks old) via CO2 asphyxiation. Fix the mouse on the mouse operating table. Disinfect the surfaces with 70% ethanol.</li>
	<li>Cut the skin of the leg to expose the muscles and femoral artery. Clamp and tear off the femoral artery using two forceps, then pull the proximal end toward the abdomen. 
	NOTE: Do not cut the femoral artery directly. Otherwise, it will cause excessive bleeding and contaminate the field of vision.</li>
	<li>Cut all the muscles around the femur.</li>
	<li>Slowly stretch the lower limbs of the mouse outward until the sound of hip joint dislocation is heard and the femoral head prolapse is visible.</li>
	<li>Separate the lower limbs from the body using scissors along the inside of the femoral head.</li>
	<li>Cut the hind legs from the end of the knee joint to obtain a free and complete femur.</li>
	<li>Remove the muscles attached to the femur using gauze. 
	NOTE: Do not tear the muscles directly. The femur of mice is delicate, its integrity must be maintained.</li>
	<li>Immerse the femur in 75% alcohol for 2-5 min.</li>
</ol>
2. Induction culture of BMDC
<ol>
	<li>Rinse the residual alcohol with PBS. Use hemostatic forceps to clamp the middle and bottom part of the femur and another set to clamp the lower end of the femur. The hemostatic forceps are applied laterally to the femur, and the femur is separated from the epiphyseal line. 
	NOTE: The epiphyseal line is not easily visible until the femur fractures. This and the next steps are all performed in a sterile environment.</li>
	<li>Use a 1 mL syringe (needle: 0.6 mm x 25 mm) to penetrate the bone marrow cavity from the epiphyseal line break and rotate the needle to penetrate the femoral head and through the bone marrow cavity. Pulse and flush the bone marrow cavity using 1 mL of the complete medium containing GM-CSF/IL-4 until the bone becomes white. 
	NOTE: Complete culture medium: 10% FBS, 1% penicillin-streptomycin, 55 &#181;M &#946;-Mercaptoethanol, 10 ng/mL GM-CSF, and 10 ng/mL IL-4.</li>
	<li>Resuspend all the cells in 24 mL of complete culture medium (~5 x 105 cells/mL). After mixing, all the medium was seeded on a 6-well plate with 4 mL/well, then incubated at 37 &#176;C with 5% CO2 for 2 days. 
	NOTE: It is not necessary to lyse erythrocytes.</li>
	<li>Replace all the medium after 2 days with medium containing GM-CSF/IL-47. On the fourth, sixth, and eighth days, replace half of the medium with the complete medium containing 10 ng/mL GM-CSF/IL-4. 
	NOTE: In this step, suspended cells such as erythrocytes and lymphocytes are removed.</li>
	<li>Take pictures every day to record cell growth. Starting from day six, harvest one well of cells per day to count the cell number and detect CD11c, CD80, and MHC II expression6,7.</li>
</ol>
3. Flow cytometric detection of the expression of CD11c, CD80, and MHC II
<ol>
	<li>After washing the DCs with PBS, resuspend 1 x 106 cells in 100 &#181;L of FACS buffer, add 0.5 &#181;g of anti-mouse CD16/32 antibody, and incubate for 10 min on ice to block non-specific antigen sites.</li>
	<li>Add 1 &#181;g of Percp/cy5.5-CD11c, 0.5 &#181;g of PE-CD80, and 0.04 &#181;g of APC-MHC II antibodies, and incubate on ice for 30 min.</li>
	<li>Centrifuge at 1,000 x g for 3 min at 4 &#176;C, remove the supernatant, add 1 mL of 4% paraformaldehyde, fix for 30 min at 4 &#176;C, and re-suspend in 300 &#181;L of FACS buffer.</li>
	<li>Perform flow cytometry.</li>
</ol>

<ol>
	<li>Huang, M. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antigen-loaded+monocyte+administration+induces+potent+therapeutic+antitumor+T+cell+responses.">Antigen-loaded monocyte administration induces potent therapeutic antitumor T cell responses.</a> Journal of Clinical Investigation. 130 (2), 774-788 (2020).</li><li>Wang, P., Dong, S., Zhao, P., He, X., Chen, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+loading+of+CTL+epitopes+onto+MHC+class+I+complexes+on+dendritic+cell+surface+in+vivo.">Direct loading of CTL epitopes onto MHC class I complexes on dendritic cell surface in vivo.</a> Biomaterials. 182, 92-103 (2018).</li><li>Banchereau, J., Steinman, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dendritic+cells+and+the+control+of+immunity.">Dendritic cells and the control of immunity.</a> Nature. 392 (6673), 245-252 (1998).</li><li>Jiang, P. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Galactosylated+liposome+as+a+dendritic+cell-targeted+mucosal+vaccine+for+inducing+protective+anti-tumor+immunity.">Galactosylated liposome as a dendritic cell-targeted mucosal vaccine for inducing protective anti-tumor immunity.</a> Acta Biomaterialia. 11, 356-367 (2015).</li><li>Shi, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Next-generation+immunotherapies+to+improve+anticancer+immunity.">Next-generation immunotherapies to improve anticancer immunity.</a> Frontiers in Pharmacology. 11, 566401 (2020).</li><li>Lutz, M. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+advanced+culture+method+for+generating+large+quantities+of+highly+pure+dendritic+cells+from+mouse+bone+marrow.">An advanced culture method for generating large quantities of highly pure dendritic cells from mouse bone marrow.</a> Journal of Immunological Methods. 223 (1), 77-92 (1999).</li><li>Son, Y. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+bulk-culture+method+for+generating+mature+dendritic+cells+from+mouse+bone+marrow+cells.">A novel bulk-culture method for generating mature dendritic cells from mouse bone marrow cells.</a> Journal of Immunological Methods. 262 (1-2), 145-157 (2002).</li><li>Guo, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fusion+protein+vaccine+based+on+Ag85B+and+STEAP1+induces+a+protective+immune+response+against+prostate+cancer.">Fusion protein vaccine based on Ag85B and STEAP1 induces a protective immune response against prostate cancer.</a> Vaccines. 9 (7), 786 (2021).</li><li>Olweus, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dendritic+cell+ontogeny:+A+human+dendritic+cell+lineage+of+myeloid+origin.">Dendritic cell ontogeny: A human dendritic cell lineage of myeloid origin.</a> Proceedings of the National Academy of Sciences of the United States of America. 94 (23), 12551-12556 (1997).</li><li>Martin, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concept+of+lymphoid+versus+myeloid+dendritic+cell+lineages+revisited:+both+CD8alpha(-)+and+CD8alpha(+)+dendritic+cells+are+generated+from+CD4(low)+lymphoid-committed+precursors.">Concept of lymphoid versus myeloid dendritic cell lineages revisited: both CD8alpha(-) and CD8alpha(+) dendritic cells are generated from CD4(low) lymphoid-committed precursors.</a> Blood. 96 (-), 2511-2519 (2000).</li><li>Anderson, D. A., Dutertre, C. A., Ginhoux, F., Murphy, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+models+of+human+and+mouse+dendritic+cell+development+and+function.">Genetic models of human and mouse dendritic cell development and function.</a> Nature Reviews: Immunology. 21 (2), 101-115 (2021).</li><li>Vu Manh, T. P., Bertho, N., Hosmalin, A., Schwartz-Cornil, I., Dalod, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigating+evolutionary+conservation+of+dendritic+cell+subset+identity+and+functions.">Investigating evolutionary conservation of dendritic cell subset identity and functions.</a> Frontiers in Immunology. 6, 260 (2015).</li><li>Scheicher, C., Mehlig, M., Zecher, R., Reske, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dendritic+cells+from+mouse+bone+marrow:+in+vitro+differentiation+using+low+doses+of+recombinant+granulocyte-macrophage+colony-stimulating+factor.">Dendritic cells from mouse bone marrow: in vitro differentiation using low doses of recombinant granulocyte-macrophage colony-stimulating factor.</a> Journal of Immunological Methods. 154 (2), 253-264 (1992).</li><li>Brasel, K., De Smedt, T., Smith, J. L., Maliszewski, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+murine+dendritic+cells+from+flt3-ligand-supplemented+bone+marrow+cultures.">Generation of murine dendritic cells from flt3-ligand-supplemented bone marrow cultures.</a> Blood. 96 (9), 3029-3039 (2000).</li><li>Mayordomo, J. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=marrow-derived+dendritic+cells+pulsed+with+synthetic+tumour+peptides+elicit+protective+and+therapeutic+antitumour+immunity.">marrow-derived dendritic cells pulsed with synthetic tumour peptides elicit protective and therapeutic antitumour immunity.</a> Nature Medicine. 1 (12), 1297-1302 (1995).</li><li>Condon, C., Watkins, S. C., Celluzzi, C. M., Thompson, K., Falo, L. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA-based+immunization+by+in+vivo+transfection+of+dendritic+cells.">DNA-based immunization by in vivo transfection of dendritic cells.</a> Nature Medicine. 2 (10), 1122-1128 (1996).</li><li>Brunner, G. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Post-prandial+administration+of+the+insulin+analogue+insulin+aspart+in+patients+with+type+1+diabetes+mellitus.">Post-prandial administration of the insulin analogue insulin aspart in patients with type 1 diabetes mellitus.</a> Diabetic Medicine. 17 (5), 371-375 (2000).</li><li>Koido, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+antitumor+immunity+by+vaccination+of+dendritic+cells+transfected+with+MUC1+RNA.">Induction of antitumor immunity by vaccination of dendritic cells transfected with MUC1 RNA.</a> Journal of Immunology. 165 (10), 5713-5719 (2000).</li><li>Jonasson, P. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strength+of+the+porcine+proximal+femoral+epiphyseal+plate:+The+effect+of+different+loading+directions+and+the+role+of+the+perichondrial+fibrocartilaginous+complex+and+epiphyseal+tubercle+-+An+experimental+biomechanical+study.">Strength of the porcine proximal femoral epiphyseal plate: The effect of different loading directions and the role of the perichondrial fibrocartilaginous complex and epiphyseal tubercle - An experimental biomechanical study.</a> Journal of Experimental Orthopaedics. 1 (1), 4 (2014).</li><li>Labeur, M. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+tumor+immunity+by+bone+marrow-derived+dendritic+cells+correlates+with+dendritic+cell+maturation+stage.">Generation of tumor immunity by bone marrow-derived dendritic cells correlates with dendritic cell maturation stage.</a> Journal of Immunology. 162 (1), 168-175 (1999).</li><li>Hinkel, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunomodulatory+dendritic+cells+generated+from+nonfractionated+bulk+peripheral+blood+mononuclear+cell+cultures+induce+growth+of+cytotoxic+T+cells+against+renal+cell+carcinoma.">Immunomodulatory dendritic cells generated from nonfractionated bulk peripheral blood mononuclear cell cultures induce growth of cytotoxic T cells against renal cell carcinoma.</a> Journal of Immunotherapy. 23 (1), 83-93 (2000).</li></ol>

All authors declare they have no conflicts of interest and that they have nothing to disclose.

Humans and mice have different DC subsets, including classical DCs (cDCs, including cDC1s and cDC2s) plasmacytoid DCs (pDCs), and monocyte-derived DCs (MoDCs)9,10,11. It is generally accepted that cDC1s regulate cytotoxic T lymphocyte (CTL) responses to intracellular pathogens and cancer, and cDC2s regulate immune responses to extracellular pathogens, parasites, and allergens12. A significant number of DCs can be produced in vitro from BM progenitor cells in mice in the presence of GM-CSF and IL-46,13,14. The purity and quantity of DCs play key roles in successful DC immunotherapy. Researchers have shown that two doses of 1 x 105 to 1 x 106 DCs could elicit efficient cytotoxic T lymphocyte (CTL) responses in a xenograft model15,16,17,18. This implies that a high number of high-purity DCs need to be cultivated to further investigate the role of DCs in tumor immunotherapy.
The traditional method of obtaining bone marrow cells is to cut the two ends of the femur and rinse with the medium6,7. In this study, we innovatively used physiological anatomical structures to sever the femur. Hemostatic forceps were used to clamp the lower end of the femur and move it laterally.The epiphyseal line is physiologically weak, making them susceptible to fractures when stressed19. After the femur is separated from the epiphyseal line, a small quantity of bone remains in the marrow cavity. The needle can easily penetrate the bone into the bone marrow cavity. The method is simple to operate, protects precious bone marrow cells, and provides a cellular basis for the culture of a high number of DCs. We cultured the DCs using a combination of 10 ng/mL GM-CSF and 10 ng/mL IL-4, which contributes more to the maturation of DCs than GM-CSF alone. Labeur and Son reported that the combined use of GM-CSF and IL-4 in the medium of DCs induced higher expression of maturation markers, such as IFN-&#611;, TNF-&#945;, and IL-6, and enhanced antigen-presenting ability7,20,21. Son et al. also proposed that the combination of GM-CSF and IL-4 promotes the maturation of DCs7,21.
In this study, we directly cultured the collected bone marrow cells without lysing the erythrocytes and separated them by gradient centrifugation, which may result in cell loss and, ultimately, to a reduction in harvested DCs. Before the medium was changed, there were several suspending cells in the culture system, including erythrocytes, T cells, B cells, and granulocytes. During co-culture, these cells may produce cytokines to promote the maturation of DCs.
In terms of limitations, this protocol only used two femurs of the mouse, excluding the smaller tibias, resulting in the loss of some mesenchymal stem cells. In short, we developed a cost-effective and efficient protocol for the isolation and generation of bone-marrow-derived dendritic cells from mice, which takes only 10 min to separate bone marrow cells. A large number of high-purity DCs were harvested after 6 days to 7 days of incubation with 10 ng/mL of GM-CSF and IL-4.

Dendritic cells (DCs) are the most powerful antigen-presenting cells (APCs) for activating na&#239;ve T cells and inducing specific cytotoxic T lymphocyte (CTL) responses against infectious diseases, allergy diseases, and tumor cells1,2,3. DCs are the primary link between innate immunity and adaptive immunity and play an essential role in immunological defense and the maintenance of immune tolerance. In the last 40 years, many researchers have sought to define the subsets of DCs and their functions in inflammation and immunity. As per those studies, DCs develop along the myeloid and lymphoid lineages from bone marrow cells. Tumor vaccines have gained significant milestones in recent years and have a promising future. Mechanically, tumor vaccines modulate the immune response and prevent tumor growth by activating cytotoxic T lymphocytes using tumor antigens. The vaccine based on DCs plays an important role in tumor immunotherapy and has been identified as one of the most promising anti-tumor therapies1,4. In addition, DCs have been widely used in the testing of new molecular-targeted drugs and immune checkpoint inhibitors5.
Researchers urgently need a high number of high-purity DCs to further study the role of DCs. However, DCs are rare in various tissues and blood, accounting for only 1% of blood cells in humans and animals. In vitro culture of bone marrow dendritic cells (BMDC) is an important method for obtaining large amounts of DC cells. Meanwhile, The Lutz protocol for generating DCs from bone marrow has been widely used by researchers6. Although the protocol is effective in obtaining DC cells, it is complex and expensive, involving the addition of high concentrations of cytokines and the lysis of red blood cells.
In this study, we report a method for isolating almost all bone marrow cells from mouse bone marrow (BM) and inducing differentiation into BMDC after 7-9 days of incubation in vitro, with a lower concentration of GM-CSF and IL-4. This procedure only takes 10 min to harvest almost all bone marrow cells and to suspend them in a complete medium. In brief, we provide an efficient and cost-effective culturing method for BMDC in this research.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>&#946;-Mercaptoethanol</td>
			<td>Solarbio</td>
			<td>M8211</td>
			<td></td>
		</tr>
		<tr>
			<td>6-well plate</td>
			<td>Corning</td>
			<td>3516</td>
			<td></td>
		</tr>
		<tr>
			<td>APC-MHC II</td>
			<td>Biolegend</td>
			<td>116417</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Gibco</td>
			<td>10100</td>
			<td></td>
		</tr>
		<tr>
			<td>PE-CD80</td>
			<td>Biolegend</td>
			<td>104707</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Solarbio</td>
			<td>P1400</td>
			<td></td>
		</tr>
		<tr>
			<td>Percp/cy5.5-CD11c</td>
			<td>Biolegend</td>
			<td>117327</td>
			<td></td>
		</tr>
		<tr>
			<td>PRMI-1640</td>
			<td>Thermo</td>
			<td>11875093</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Mouse GM-CSF</td>
			<td>Solarbio</td>
			<td>P00184</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Mouse IL-4</td>
			<td>Solarbio</td>
			<td>P00196</td>
			<td></td>
		</tr>
		<tr>
			<td>TruStain Fc PLUS (anti-mouse CD16/32) Antibody</td>
			<td>Biolegend</td>
			<td>156603</td>
			<td></td>
		</tr>
	</tbody>
</table>

economical and efficient protocol for isolating and culturing bone marrow-derived dendritic cells from mice

The demand for dendritic cells (DCs) is gradually increasing as immunology research advances. However, DCs are rare in all tissues. The traditional method for isolating DCs primarily involves inducing bone marrow (BM) differentiation into DCs by injecting large doses (&#62;10 ng/mL) of granulocyte-macrophage colony-stimulating factor/interleukin-4 (GM-CSF/IL-4), making the procedure complex and expensive. In this protocol, using all BM cells cultured in 10 ng/mL GM-CSF/IL-4 medium, after 3-4 half-culture exchanges, up to 2.7 x 107 CD11c+ cells&#160;(DCs) per mouse (two femurs) were harvested with a purity of 80%-95%. After 10 days in culture, the expression of CD11c, CD80, and MHC II increased, whereas the number of cells decreased. The number of cells peaked after 7 days of culture. Moreover, this method only took 10 min to harvest all bone marrow cells, and a high number of DCs were obtained after 1 week of culture.

The 1 x 107-1.7 x 107 cells were extracted from two femurs and were re-suspended in 24 mL of medium before being planted in a 6-well plate (Figure 1A). After 2 days, non-adherent cells were removed by completely changing the culture medium. Before changing the medium, a significant number of suspended cells were observed (Figure 1B). After 3 days of culture, small cell colonies began to form. On the sixth day, the size and number of colonies increased significantly. On the seventh day, the number of cells peaked (22 x 106-27 x 106) and then dropped gradually (Figure 2A). The surface of the DC cells became rough with longer pseudopodia, exhibiting typical mature DC cell morphology (Figure 2B). Flow cytometric analysis showed that the ratio of CD11c positive to total cells was 71% on the sixth day, whereas the ratio increased to 96.1% on the tenth day (Figure 2C,2D).
To evaluate the expression of co-stimulatory molecules, CD11c, CD80, and MHC II were co-stained8. As shown as Figure 3A, the expression of CD11c, CD80, and MHC II gradually increased with increasing cultivation time from day 6 to day 10. Additionally, flow cytometric analysis showed a gradual increase in the proportions of CD11c and CD80 double-positive, CD11c and MHCII double-positive (Figure 3B,3D), and triple-positive cells (Figure 3C,3D).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/63125/63125fig01.jpg" /> 
Figure 1: Representative images of DCs at different culture times. (A) Flow-chart of culturing BMDC. (B) Representative images of DCs at different culture times. Bone marrow cells were suspended in 24 mL of culture medium with 10 ng/mL GM-CSF and IL-4 and seeded in a 6-well plate. BF, before changing culture medium; AF, after changing culture medium. Red arrow, DC colony. <a href="https://www.jove.com/files/ftp_upload/63125/63125fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/63125/63125fig02.jpg" /> 
Figure 2: The number and purity of DCs at different culture times. (A) Total number of cells in all culture medium. (B) Representative images of DCs. (C,D) Flow cytometric and graphical representation of the analysis of the proportion of DCs. Positive cells were sorted by CD11c. <a href="https://www.jove.com/files/ftp_upload/63125/63125fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/63125/63125fig03.jpg" /> 
Figure 3: The expression of co-stimulatory molecules in DCs. (A) The expression of CD11c, CD80, and MHC &#921;&#921; in DCs. (B) Flow cytometric analysis of the proportion of CD11c and CD80 double-positive, CD11c and MHC &#921;&#921; double-positive, and triple-positive cells. (C, D) Flow cytometric analysis from Day 6- Day 10 and graphical representation to show the statistical analysis. <a href="https://www.jove.com/files/ftp_upload/63125/63125fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Economical and Efficient Protocol for Isolating and Culturing Bone Marrow-derived Dendritic Cells from Mice at JoVE.com

Economical and Efficient Protocol for Isolating and Culturing Bone Marrow-derived Dendritic Cells from Mice

Here, we present an economical and efficient method to isolate and generate high-purity bone marrow-derived dendritic cells from mice after 7 days of culture with 10 ng/mL GM-CSF/IL-4.

The demand for dendritic cells (DCs) is gradually increasing as immunology research advances. However, DCs are rare in all tissues. The traditional method ...

economical-efficient-protocol-for-isolating-culturing-bone-marrow

The University of Tokyo

Research

JoVE Journal

Immunology and Infection

8.0K Views.  The Second Hospital of Tianjin Medical University. Here, we present an economical and efficient method to isolate and generate high-purity bone marrow-derived dendritic cells from mice after 7 days of culture with 10 ng/mL GM-CSF/IL-4.

Video: Economical and Efficient Protocol for Isolating and Culturing Bone Marrow-derived Dendritic Cells from Mice

Optimized Protocol for Efficient Transfection of Dendritic Cells without Cell Maturation

Dendritic cells (DCs) can be considered sentinels of the immune system which play a critical role in its initiation and response to infection1. Detection of pathogenic antigen by na&iuml;ve DCs is through pattern recognition receptors (PRRs) which are able to recognize specific conserved structures referred to as pathogen-associated molecular patterns (PAMPS). Detection of PAMPs by DCs triggers an intracellular signaling cascade resulting in their activation and transformation to mature DCs. This process is typically characterized by production of type 1 interferon along with other proinflammatory cytokines, upregulation of cell surface markers such as MHCII and CD86 and migration of the mature DC to draining lymph nodes, where interaction with T cells initiates the adaptive immune response2,3. Thus, DCs link the innate and adaptive immune systems. 
The ability to dissect the molecular networks underlying DC response to various pathogens is crucial to a better understanding of the regulation of these signaling pathways and their induced genes. It should also help facilitate the development of DC-based vaccines against infectious diseases and tumors. However, this line of research has been severely impeded by the difficulty of transfecting primary DCs4.
Virus transduction methods, such as the lentiviral system, are typically used, but carry many limitations such as complexity and bio-hazardous risk (with the associated costs)5,6,7,8. Additionally, the delivery of viral gene products increases the immunogenicity of those transduced DCs9,10,11,12. Electroporation has been used with mixed results13,14,15, but we are the first to report the use of a high-throughput transfection protocol and conclusively demonstrate its utility.
In this report we summarize an optimized commercial protocol for high-throughput transfection of human primary DCs, with limited cell toxicity and an absence of DC maturation16. Transfection efficiency (of GFP plasmid) and cell viability were more than 50% and 70% respectively. FACS analysis established the absence of increase in expression of the maturation markers CD86 and MHCII in transfected cells, while qRT-PCR demonstrated no upregulation of IFN&beta;. Using this electroporation protocol, we provide evidence for successful transfection of DCs with siRNA and effective knock down of targeted gene RIG-I, a key viral recognition receptor16,17, at both the mRNA and protein levels.

We present our optimized high-throughput nucleofection protocol as an efficient way of transfecting primary human monocyte-derived dendritic cells with either plasmid DNA or siRNA without causing cell maturation. We further provide evidence for successful siRNA silencing of targeted gene RIG-I at both the mRNA and protein levels.

Dendritic cells (DCs) can be considered sentinels of the immune system which play a critical role in its initiation and response to infection1. Detection ...

Generation and Labeling of Murine Bone Marrow-derived Dendritic Cells with Qdot Nanocrystals for Tracking Studies

Dendritic cells (DCs) are professional antigen presenting cells (APCs) found in peripheral tissues and in immunological organs such as thymus, bone marrow, spleen, lymph nodes and Peyer's patches 1-3. DCs present in peripheral tissues sample the organism for the presence of antigens, which they take up, process and present in their surface in the context of major histocompatibility molecules (MHC). Then, antigen-loaded DCs migrate to immunological organs where they present the processed antigen to T lymphocytes triggering specific immune responses. One way to evaluate the migratory capabilities of DCs is to label them with fluorescent dyes 4.
Herewith we demonstrate the use of Qdot fluorescent nanocrystals to label murine bone marrow-derived DC. The advantage of this labeling is that Qdot nanocrystals possess stable and long lasting fluorescence that make them ideal for detecting labeled cells in recovered tissues. To accomplish this, first cells will be recovered from murine bone marrows and cultured for 8 days in the presence of granulocyte macrophage-colony stimulating factor in order to induce DC differentiation. These cells will be then labeled with fluorescent Qdots by short in vitro incubation. Stained cells can be visualized with a fluorescent microscopy. Cells can be injected into experimental animals at this point or can be into mature cells upon in vitro incubation with inflammatory stimuli. In our hands, DC maturation did not determine loss of fluorescent signal nor does Qdot staining affect the biological properties of DCs. Upon injection, these cells can be identified in immune organs by fluorescent microscopy following typical dissection and fixation procedures.

Dendritic cells uptake antigens and migrate towards immune organs to present processed antigens to T cells. Qdot nanocrystal labeling provides a long-lasting and stable fluorescent signal. This allows tracking of dendritic cells to different organs by fluorescent microscopy.

Dendritic cells (DCs) are professional antigen presenting cells (APCs) found in peripheral tissues and in immunological organs such as thymus, bone ...

Isolating And Immunostaining Lymphocytes and Dendritic Cells from Murine Peyer's Patches

Peyer's patches (PPs) are integral components of the gut-associated lymphoid tissues (GALT) and play a central role in intestinal immunosurveillance and homeostasis. Particulate antigens and microbes in the intestinal lumen are continuously sampled by PP M cells in the follicle-associated epithelium (FAE) and transported to an underlying network of dendritic cells (DCs), macrophages, and lymphocytes. In this article, we describe protocols in which murine PPs are (i) dissociated into single cell suspensions and subjected to flow cytometry and (ii) prepared for cryosectioning and immunostaining. For flow cytometry, PPs are mechanically dissociated and then filtered through 70 &mu;m membranes to generate single cell suspensions free of epithelial cells and large debris. Starting with 20-25 PPs (from four mice), this quick and reproducible method yields a population of &gt;2.5 x 106 cells with &gt;90% cell viability. For cryosectioning, freshly isolated PPs are immersed in Optimal Cutting Temperature (OCT) medium, snap-frozen in liquid nitrogen, and then sectioned using a cryomicrotome. Tissue sections (5-12 &mu;m) are air-dried, fixed with acetone or methanol, and then subjected to immunolabeling.

Isolating And Immunostaining Lymphocytes and Dendritic Cells from Murine Peyer&#039;s Patches

There is an increasing interest in understanding the immunological functions of specific subpopulations of cells in Peyer's patches (PPs), the primary inductive sites of gut-associated lymphoid tissues. Here we outline parallel protocols for preparing PP single cell preparations for flow cytometric analysis and PP cryosections for immunostaining.

Peyer's  patches (PPs) are integral components of the gut-associated lymphoid tissues  (GALT) and play a central role in intestinal immunosurveillance and ...

Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic ...

Bone Marrow-derived Macrophage Production

Macrophages are critical components of the innate and adaptive immune responses, and they are the first line of defense against foreign invaders because of their powerful microbicidal activities. Macrophages are widely distributed throughout the body and are present in the lymphoid organs, liver, lungs, gastrointestinal tract, central nervous system, bone, and skin. Because of their repartition, they participate in a wide range of physiological and pathological processes. Macrophages are highly versatile cells that are able to recognize microenvironmental alterations and to maintain tissue homeostasis. Numerous pathogens have evolved mechanisms to use macrophages as Trojan horses to survive, replicate in, and infect both humans and animals and to propagate throughout the body. The recent explosion of interest in evolutionary, genetic, and biochemical aspects of host-pathogen interactions has renewed scientific attention regarding macrophages. Here, we describe a procedure to isolate and cultivate macrophages from murine bone marrow that will provide large numbers of macrophages for studying host-pathogen interactions as well as other processes.

Macrophages have long been recognized as a critical component of the innate and adaptive immune responses. The recent explosion of knowledge pertaining to evolutionary, genetic, and biochemical aspects of the interaction between macrophages and microbes has renewed scientific attention to macrophages. This article describes a method to differentiate macrophages from mouse bone marrow.

Macrophages are critical components of the innate and adaptive immune responses, and they are the first line of defense against foreign invaders because ...

Isolation and Intravenous Injection of Murine Bone Marrow Derived Monocytes

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of various fields in biomedical science. The method described below is a simple and effective way to isolate murine monocytes from heterogeneous bone marrow.
Bone marrow from the femur and tibia of Balb/c mice is harvested by flushing with phosphate buffered saline (PBS). Cell suspension is supplemented with macrophage-colony stimulating factor (M-CSF) and cultured on ultra-low attachment surfaces to avoid adhesion-triggered differentiation of monocytes. The properties and differentiation of monocytes are characterized at various intervals. Fluorescence activated cell sorting (FACS), with markers like CD11b, CD115, and F4/80, is used for phenotyping. At the end of cultivation, the suspension consists of 45%&#177; 12% monocytes. By removing adhesive macrophages, the purity can be raised up to 86%&#177; 6%. After the isolation, monocytes can be utilized in various ways, and one of the most effective and common methods for in vivo delivery is intravenous tail vein injection. 
This technique of isolation and application is important for mouse model studies, especially in the fields of inflammation or immunology. Monocytes can also be used therapeutically in mouse disease models.

Here we present a protocol that generates large amounts of murine monocytes from heterogeneous bone marrow for translational applications. In comparison to others, this new method helps reduce the number of sacrificed animals and lowers costs by avoiding expensive methods such as high gradient magnetic cell separation (MACS).

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of ...

Generation and Identification of GM-CSF Derived Alveolar-like Macrophages and Dendritic Cells From Mouse Bone Marrow

Macrophages and dendritic cells (DCs) are innate immune cells found in tissues and lymphoid organs that play a key role in the defense against pathogens. However, they are difficult to isolate in sufficient numbers to study them in detail, therefore, in vitro models have been developed. In vitro cultures of bone marrow-derived macrophages and dendritic cells are well-established and valuable methods for immunological studies. Here, a method for culturing and identifying both DCs and macrophages from a single culture of primary mouse bone marrow cells using the cytokine granulocyte macrophage colony-stimulating factor (GM-CSF) is described. This protocol is based on the established procedure first developed by Lutz et al. in 1999 for bone marrow-derived DCs. The culture is heterogeneous, and MHCII and fluoresceinated hyaluronan (FL-HA) are used to distinguish macrophages from immature and mature DCs. These GM-CSF derived macrophages provide a convenient source of in vitro derived macrophages that closely resemble alveolar macrophages in both phenotype and function.

Bone marrow cells cultured with granulocyte macrophage colony stimulating factor (GM-CSF) generate a heterogeneous culture containing macrophages and dendritic cells (DCs). This method highlights using MHCII and hyaluronan (HA) binding to differentiate macrophages from the DCs in the GM-CSF culture. Macrophages in this culture have many similarities to alveolar macrophages.

Macrophages and dendritic cells (DCs) are innate immune cells found in tissues and lymphoid organs that play a key role in the defense against pathogens. ...

Fluorescence-activated Cell Sorting for Purification of Plasmacytoid Dendritic Cells from the Mouse Bone Marrow

Fluorescence-activated cell sorting (FACS) is a technique to purify specific cell populations based on phenotypes detected by flow cytometry. This method enables researchers to better understand the characteristics of a single cell population without the influence of other cells. Compared to other methods of cell enrichment, such as magnetic-activated cell sorting (MCS), FACS is more flexible and accurate for cell separation due to the ability of phenotype detection by flow cytometry. In addition, FACS is usually capable of separating multiple cell populations simultaneously, which improves the efficiency and diversity of experiments. Although FACS has some limitations, it has been broadly used to purify cells for functional studies in both in vitro and in vivo settings. Here we report a protocol using fluorescence-activated cell sorting to isolate a very rare population of immune cells, plasmacytoid dendritic cells (pDC), with high purity from the bone marrow of lupus-prone mice for in vitro functional studies of pDC.

We report a protocol using fluorescence-activated cell sorting to isolate plasmacytoid dendritic cells (pDC) with high purity from the bone marrow of lupus-prone mice for functional studies of pDC.

Fluorescence-activated cell sorting (FACS) is a technique to purify specific cell populations based on phenotypes detected by flow cytometry. This method ...

An In Vivo Mouse Model to Measure Na&#239;ve CD4 T Cell Activation, Proliferation and Th1 Differentiation Induced by Bone Marrow-derived Dendritic Cells

Quantification of na&#239;ve CD4 T cell activation, proliferation, and differentiation to T helper 1 (Th1) cells is a useful way to assess the role played by T cells in an immune response. This protocol describes the in vitro differentiation of bone marrow (BM) progenitors to obtain granulocyte macrophage colony-stimulating factor (GM-CSF) derived-dendritic cells (DCs). The protocol also describes the adoptive transfer of ovalbumin peptide (OVAp)-loaded GM-CSF-derived DCs and na&#239;ve CD4 T cells from OTII transgenic mice in order to analyze the in vivo activation, proliferation, and Th1 differentiation of the transferred CD4 T cells. This protocol circumvents the limitation of purely in vivo methods imposed by the inability to specifically manipulate or select the studied cell population. Moreover, this protocol allows studies in an in vivo environment, thus avoiding alterations to functional factors that may occur in vitro and including the influence of cell types and other factors only found in intact organs. The protocol is a useful tool for generating changes in DCs and T cells that modify adaptive immune responses, potentially providing important results to understand the origin or development of numerous immune associated diseases.

An &lt;em&gt;In Vivo&lt;/em&gt; Mouse Model to Measure Na&amp;#239;ve CD4 T Cell Activation, Proliferation and Th1 Differentiation Induced by Bone Marrow-derived Dendritic Cells

Here, we present a protocol for the in vivo determination of na&#239;ve CD4 T cell (T cell) activation, proliferation, and Th1 differentiation induced by GM-CSF bone marrow (BM)-derived dendritic cells (DCs). In addition, this protocol describes BM and T-cell isolation, DC generation, and DC and T-cell adoptive transfer.

Quantification of na&#239;ve CD4 T cell activation, proliferation, and differentiation to T helper 1 (Th1) cells is a useful way to assess the role played ...

Novel Protocol for Generating Physiologic Immunogenic Dendritic Cells

Extracorporeal photochemotherapy (ECP) is a widely used cancer immunotherapy for cutaneous T cell lymphoma (CTCL), operative in over 350 university centers worldwide. While ECP&#8217;s clinical efficacy and exemplary safety profile have driven its widespread use, elucidation of the underlying mechanisms has remained a challenge, partly owing to lack of a laboratory ECP model. To overcome this obstacle and create a simple, user-friendly platform for ECP research, we developed a scaled-down version of the clinical ECP leukocyte-processing device, suitable for work with both mouse models, and small human blood samples. This device is termed the Transimmunization (TI) chamber, or plate. In a series of landmark experiments, the miniaturized device was used to produce a cellular vaccine that regularly initiated therapeutic anti-cancer immunity in several syngeneic mouse tumor models. By removing individual factors from the experimental system and ascertaining their contribution to the in vivo anti-tumor response, we then elucidated key mechanistic drivers of ECP immunizing potential. Collectively, our results revealed that anti-tumor effects of ECP are initiated by dendritic cells (DC), physiologically generated through blood monocyte interaction with platelets in the TI plate, and loaded with antigens from tumor cells whose apoptotic cell death is finely titrated by exposure to the photoactivatable DNA cross-linking agent 8-methoxypsoralen and UVA light (8-MOPA). When returned to the mouse, this cellular vaccine leads to specific and transferable anti-tumor T cell immunity. We verified that the TI chamber is also suitable for human blood processing, producing human DCs fully comparable in activation state and profile to those derived from the clinical ECP chamber. The protocols presented here are intended for ECP studies in mouse and man, controlled generation of apoptotic tumor cells with 8-MOPA, and rapid production of physiologic human and mouse monocyte-derived DCs for a variety of applications.

The transimmunization (TI) device or plate and related protocols have been developed to replicate the key features of extracorporeal photochemotherapy (ECP), in an experimental setting, allowing for production of physiologically activated, tunable dendritic cells (DCs) for cancer immunotherapy.

Extracorporeal photochemotherapy (ECP) is a widely used cancer immunotherapy for cutaneous T cell lymphoma (CTCL), operative in over 350 university ...