An optimized method for the induction and purification of mouse bone marrow dendritic cells

Dendritic cells (DCs) play an essential role in the initiation of adaptive immune responses, but they are rare in all organs. The traditional methods used to increase the yield and purity of DCs are the early removal of granulocyte culture medium and the isolation of high-purity DCs by magnetic-activated cell sorting (MACS). This study provides a more rapid and economical optimization method to obtain more high-purity DCs. (i) We harvested 18% more bone marrow (BM) cells by using forceps to crack the epiphysis instead of cutting it with scissors during BM cell extraction. (ii) When the cells in the culture medium that is discarded on day 3 in the traditional method were centrifuged and then added back to the petri dish, the DC yield on day 5 increased by 61%. (iii) On the third day, the addition of fresh medium and the retention of the original medium rather than discarding it increased the number of DCs harvested on the fifth day by 137%. (i-iii) The improved method cost an average of 74% less than the conventional method and yielded the same number and function of cells. (iv) The initial number of BM cells was increased by 15% in 4-week-old mice compared with 8-week-old mice. (v) The Percoll density centrifugation (PDS) method was used to purify DCs on day 6 after induction, and the purity of the DCs was greater than 90%, which showed no significant difference from the MACS method. However, the yield of the PDS method increased by 21%. In addition, the PDS method has a lower cost, with an average purification cost of 4 CNY ($0.58) compared with 648 CNY ($93.25) for MACS, reducing the cost by 99%. Therefore, high-purity and high-yield DCs can be rapidly obtained through a five-step improvement in the process of BM cell extraction, induction and purification.