Bone-marrow-derived macrophage (BMDM) refers to macrophage cells that are generated in a research laboratory from mammalian bone marrow cells. ^{[1] [2] [3]} BMDMs can differentiate into mature macrophages in the presence of growth factors and other signaling molecules. ^{[1] [2]} Undifferentiated bone marrow cells are cultured in the presence of macrophage colony-stimulating factor (M-CSF; CSF-1). ^[3] M-CSF is a cytokine and growth factor that is responsible for the proliferation and commitment of myeloid progenitors into monocytes (which then mature into macrophages). ^{[3] [4]} Macrophages have a wide variety of functions in the body including phagocytosis of foreign invaders and other cellular debris, releasing cytokines to trigger immune responses, and antigen presentation. ^[2] BMDMs provide a large homogenous population of macrophages that play an increasingly important role in making macrophage-related research possible and financially feasible. ^[5]

In order to produce BMDMs, mesenchymal stem cells are removed from the tibia or femur of mice. ^[6] Since BMDMs are derived from bone marrow, withdrawn cells are healthy and naïve (or unactivated), regardless of the condition of donor mice. ^[5] After removal, stem-cells are incubated with CSF-1. ^[6] Without CSF-1, the cells enter an inactive state but can reinitiate growth and differentiation if stimulated later. ^[6] Mature macrophages and fibroblasts, which may carry unwanted growth factors, are removed. ^[6] Next, IL-3 and IL-1, two growth factors, are often added to increase yield and promote rapid terminal differentiation. ^[6] Exogenous media containing growth factors and other serums must also be added to make the cells continually viable. ^[6] Full growth and differentiation take approximately 5–8 days. ^[6]

Millions of BMDMs can be derived from one mouse and frozen for years. After being thawed BMDMs can respond to a variety of stimuli such as LPS, IFN-γ, PAMPs, NF-κB, and IRF3. ^{[1] [5] [7]} These signals induce translation of genes that produce cytokines and determine if macrophages are M1 (pro-inflammatory) or M2 (anti-inflammatory). ^[2] If BMDMs are not frozen, they age and become less viable as CSF-1 and growth factors in their media decreases. ^[1]

Proliferation of BMDMs can also be inhibited by a number of reagents. ^[6] For example, growth and differentiation is dependent on CSF-1 and a functional CSF-1 receptor, a member of the tyrosine kinase family. ^[6] Without a functional CSF-1 receptors, stem cells cannot respond to CSF-1 stimuli and therefore cannot differentiate; interferons can cause a down regulation of the CSF-1 receptor. ^[6] Additionally, without stimuli like LPS to induce macrophage maturation to M1 or M2, mice accumulate a large pool of monocytes, the precursor cells to macrophages, which are less helpful for macrophage-specific research ^[6]