Abstract Body: Background: EMS is a revascularization surgery for moyamoya disease (MMD) that uses the temporalis muscle flap as a donor organ to create a vascular niche, reducing ischemic events by forming collateral vessels. This suggests EMS promotes tissue recovery through increased angiogenesis. The immune response, similar to the angiogenic response, plays a dual role in post-stroke repair and injury. While microglia, monocytes, and neutrophils in the innate immune system are typically seen as destructive after stroke, they also contribute to brain repair. T and B cells in the adaptive immune system also play roles in CNS injury and repair. Our study aimed to evaluate the immune response following EMS treatment after transient middle cerebral artery occlusion (MCAo) injury.
Methods: We used young C57BL/6 mice (2-3 months old, with equal numbers of males and females). Ischemic stroke was induced using a 60-minute MCAo, followed by reperfusion. Laser Doppler confirmed successful occlusion. EMS surgery was performed 4 hours after MCAo onset in 50% of the mice (MCAo+EMS), with the remaining 50% serving as controls (MCAo-only). Mice were sacrificed 7 days after MCAo onset to assess the immune response. Perilesional ischemic brain tissue and PBMCs isolated from whole blood were analyzed by flow cytometry.
Results: We found a significant difference between MCAo-only vs MCAo+EMS in blood immune cells. B cells were more abundant in the MCAo-only group (1.5-fold, P<0.05), while NK cells and monocytes/macrophages (Mo/Mø) were increased in the MCAo+EMS group (1.5-2-fold, P<0.05). NK cells, known for cytokine production promoting angiogenesis, and Mo/Mø, which regulate CNS immune defense, were more prominent in the EMS treatment group.
Conclusion: Diverse immune responses may affect angiogenesis process to improve post EMS outcome. Future studies will help to determine how immune responses affect angiogenesis during long-term recovery after stroke.