Bone marrow-derived myeloid cells transiently colonize the brain during postnatal development and interact with glutamatergic synapses

• Published in: iScience Vol. 27; no. 7; p. 110037
• Main Authors: Carrier, Micaël, Robert, Marie-Ève, St-Pierre, Marie-Kim, Ibáñez, Fernando González, Gonçalves de Andrade, Elisa, Laroche, Audrée, Picard, Katherine, Vecchiarelli, Haley A., Savage, Julie C., Boilard, Éric, Desjardins, Michèle, Tremblay, Marie-Ève
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 19.07.2024; Elsevier
• Subjects: Biological sciences; Cellular neuroscience; Developmental neuroscience; Natural sciences; Neuroscience; Neuroscience; Developmental neuroscience; Biological sciences; Natural sciences; Cellular neuroscience
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2024.110037

Although the roles of embryonic yolk sac-derived, resident microglia in neurodevelopment were extensively studied, the possible involvement of bone marrow-derived cells remains elusive. In this work, we used a fate-mapping strategy to selectively label bone marrow-derived cells and their progeny in the brain (FLT3+IBA1+). FLT3+IBA1+ cells were confirmed to be transiently present in the healthy brain during early postnatal development. FLT3+IBA1+ cells have a distinct morphology index at postnatal day(P)0, P7, and P14 compared with neighboring microglia. FLT3+IBA1+ cells also express the microglial markers P2RY12 and TMEM119 and interact with VGLUT1 synapses at P14. Scanning electron microscopy indeed showed that FLT3+ cells contact and engulf pre-synaptic elements. Our findings suggest FLT3+IBA1+ cells might assist microglia in their physiological functions in the developing brain including synaptic pruning which is performed using their purinergic sensors. Our findings stimulate further investigation on the involvement of peripheral macrophages during homeostatic and pathological development. [Display omitted] •FLT3+IBA1+ cells infiltrate the brain in the first 2 weeks of life peaking at day 14•FLT3+IBA1+ cells are morphologically distinct from microglia, evolving with time•FLT3+IBA1+ cells express TMEM119 and P2RY12 and engulf glutamatergic synapses•Cells show similar side and forward scatter than marginal microglia Natural sciences; Biological sciences; Neuroscience; Developmental neuroscience; Cellular neuroscience