Abstract 192: Bone Marrow Mononuclear Cells May Enhance Recovery After Stroke By Modulating the Microglial Response
Background: Autologous bone marrow mononuclear cells (MNCs) have been shown in multiple labs to improve stroke recovery in animal models but the mechanisms remain unclear. We assessed whether MNCs modulate macrophage-microglia responses in acute stroke.
Methods: C57/BL mice were subjected to middle cerebral artery occlusion (MCAo) for 60 minutes or sham surgery. 24 hours later, they were randomized to receive saline infusion IV or 1x 106 autologous MNCs IV. At various time points after stroke, 1ml peripheral blood was collected and brains were harvested up to day14. Peripheral blood was labeled with anti-mouse CD45, CD115, F4/80 or Gr-1 antibodies and then assessed by flow cytometry. Microglia were isolated from brains by Optiprep gradient and stained with anti-mouse CD11b, CD45, and CD86 antibodies for evaluation by flow cytometry. For gene expression analyses by RT-PCR, microglia-macrophages were further sorted by magnetic activated-cells sorting using CD11b antibody.
Results: 1) At day 2 after stroke, the percentage of CD115+ monocytes and CD115+/Gr-1lowcells were significantly decreased in whole peripheral blood but F4/80+ macrophages were increased. MNCs increased the abundance of CD115+/Gr-1low cells and decreased the abundance of F4/80+ macrophages in peripheral blood compared to saline control at day 2 after stroke (n=5, p<0.05); 2)Compared to saline, MNCs significantly reduced the total number of CD11b+ microglia-macrophages in the stroke-affected hemisphere at day 2 to day 6. MNCs significantly decreased the proportion of CD11b+/CD45high among CD11b+ cells at day 2 and day 4 and CD86+ cells among CD11b+ cells at day 2. Among CD11b+ microglia-macrophages isolated from the ipsilateral hemisphere of MNC treated mice, compared to saline treated controls, iNOS and IL-1β genes expression were down-regulated at day 2. At day 6, iNOS remained down-regulated while now IL-10, Arganase-1 and CD206 genes expression (markers for the “healing” macrophage phenotype) were up-regulated (n=3 to 5, p<0.05).
Conclusions: MNCs may enhance recovery after stroke by altering monocyte trafficking and changing microglial polarization into a healing phenotype.
Author Disclosures: B. Yang: None. K. Parsha: None. E. Migliati: None. S. Savitz: None.
- © 2014 by American Heart Association, Inc.