Ischemic conditions are a leading cause of death for both men and women. Ischemia, a condition characterized by reduced blood flow and oxygen to an organ. Re-establishment of blood flow, or reperfusion, and re-oxygenation of the affected area following an ischemic episode is critical to limit irreversible damage. However, reperfusion also associates potentially damaging consequences. For instance, increased vascular permeability is an important contributor to edema and tissue damage following ischemic events. Here the inventors shows that genetic inhibition of PI3K-C2? reduces cerebral infarction in two ischemia/reperfusion (I/R) models and improves neurological outcome. The genetic inhibition stabilizes the blood–brain barrier (BBB) after ischemic stroke and reduces inflammation. Accordingly, the presentrninvention relates to a method for the preservation of vascular endothelial cell barrier integrity in a patient in need thereof comprising administering to the subject a therapeutically effective amount of a PI3KC2? inhibitor.