CD47 inhibiting antibody alleviates brain injury after intraventricular hemorrhage in aged rats

INTRODUCTION: Intraventricular hemorrhage (IVH) is a major contributor to acute brain injury and post-hemorrhagic hydrocephalus, especially in older adults. CD47 on erythrocytes delivers a "don't-eat-me" signal that inhibits macrophage/microglia (M/MΦ) mediated phagocytosis, slowing hematoma resolution. While CD47 blockade enhances hematoma clearance after IVH in young animals and in intracerebral hemorrhage models, its therapeutic potential in aged IVH has not been examined. METHODS: Eighteen-month-old male Fischer 344 rats received intraventricular injections of autologous arterial blood mixed with either anti-CD47 antibody or isotype IgG. Saline-injected rats served as additional controls. MRI was performed post-IVH at 4 h, days 1 and 3 to quantify ventricular volume, T2* intraventricular hematoma volume, and T2* non-hypointense lesion volume (early hemolysis). Histological analyses assessed M/MΦ activation, choroid plexus and periventricular immune cell accumulation, ventricular wall injury, and hippocampal neuronal survival. RESULTS: cells in white matter. CD47 inhibition further attenuated ventricular wall damage on day 3 and reduced neuronal loss in the hippocampal CA1 region. CONCLUSION: Blocking erythrocyte CD47 facilitates hematoma resolution, reduces hemolysis and hydrocephalus, enhances M/MΦ recruitment across multiple anatomical routes, and mitigates ependymal damage and neuronal injury after IVH in aged rats. These findings support CD47 as a promising therapeutic target for IVH, particularly in the aging population.