Transplantation chemotherapy eliminates regenerative capacity of brain’s innate immune cells

Brain microglia ( green ) initiating expression of cell division marker ( red ), but unable divide due to co-expression of a senescence marker ( blue ), due to the chemotherapy treatment (busulfan). K. Sailor/ PM Lledo, Institut Pasteur. Brain microglia (green) initiating expression of cell division marker (red), but unable divide due to co-expression of a senescence marker (blue), due to the chemotherapy treatment (busulfan). K. Sailor/ PM Lledo, Institut Pasteur. Annually over 50,000 bone marrow transplantations occur worldwide as a therapy for multiple cancerous and non-cancerous diseases. Yet, how this procedure gives rise to bone marrow-derived cells that engraft the brain, despite being absent in the normal brain, remains unknown. In the present study, scientists from the Institut Pasteur, the CNRS and the Paris Brain Institute (Inserm) discovered how the host's microglia, the brain's innate immune cells, are replaced by bone marrow-derived macrophages.