Microglia differentiation using a culture system for the expansion of mice non-adherent bone marrow stem cells

INTRODUCTION: Studying primary adult microglia is hampered because of the difficult isolation procedure and the low cell yield. We therefore established a differentiation protocol using a culture system developed for the expansion of non-adherent bone marrow cells. METHODS: Non-adherent bone marrow derived stem cells (NA-BMC) are derived by selective adhesion (‘preplating’) and are non adhesive adult stem cells. We investigated the changes in bone marrow cell populations by this repeated selective adhesion and compared the potential of the derived cells to differentiate towards microglia. Cells were differentiated with astrocyte conditioned medium (ACM) and granulocyte-monocyte colony stimulating factor (GM-CSF). RESULTS: NA-BMC cultures show a steep raise in the fraction of stem cells during the cultivation time and the differentiation potential is of the same quality as established protocols. Around 70% of the cells are microglia defined as being positive for CD11b/CD45 and show phagocytosis activity and oxidative bursts. CONCLUSION: The non-adherent cell system has the advantage that is produces stem cell progenitors during expansion and provides good microglial differentiation.