Development of endothelial-targeted CD39 as a therapy for ischaemic stroke

Background Ischaemic stroke is characterized by a necrotic lesion in the brain surrounded by an area of dying cells termed the penumbra. Salvaging the penumbra either with thrombolysis or mechanical retrieval is the cornerstone of stroke management. At-risk neuronal cells release extracellular adenosine triphosphate (eATP) triggering microglial activation and causing a thromboinflammatory response culminating in endothelial activation and vascular disruption. This is further aggravated by ischaemia-reperfusion (I/R) injury that follows all reperfusion therapies. The ecto-enzyme CD39 regulates eATP by hydrolysing to adenosine which has anti-thrombotic and anti-inflammatory properties and reverses I/R injury. Methods We developed anti-VCAM-CD39 that targets the antithrombotic and anti-inflammatory properties of recombinant CD39 to the activated endothelium of the penumbra by binding to vascular cell adhesion molecule (VCAM)-1. Mice were subjected to 30 minutes of middle cerebral artery occlusion (MCAo) and analysed at 24h. Anti-VCAM-CD39 or control agents (saline, non-targeted CD39, or anti-VCAM-inactive CD39) were given at 3h post-MCAo. Results Anti-VCAM-CD39 treatment reduced neurological deficit; MRI confirmed significantly smaller infarcts together with an increase in cerebrovascular perfusion. Anti-VCAM-CD39 also restored blood brain barrier (BBB) integrity and reduced microglial activation. Coadministration of anti-VCAM-CD39 with thrombolytics (tPA) further reduced infarct volumes and attenuated BBB permeability with no associated increase in intracranial haemorrhage. Conclusion Anti-VCAM-CD39, uniquely targeted to endothelial cells, could be a new stroke therapy even when administered 3 h post ischaemia and may further synergise with thrombolytic therapy to improve stroke outcomes.