An Activated Protein C Analog With Reduced Anticoagulant Activity Extends the Therapeutic Window of Tissue Plasminogen Activator for Ischemic Stroke in Rodents

Abstract

Background and purpose Tissue plasminogen activator (tPA) is the only approved therapy for acute ischemic stroke. However, tPA has a brief therapeutic window. Its side effects include intracerebral bleeding and neurotoxicity. Therefore, a combination therapy with tPA and agents that can extend the therapeutic window of tPA and/or counteract its side effects are warranted. Here, we studied whether 3K3A-APC, a neuroprotective analog of activated protein C (APC) with reduced anticoagulant activity, can enhance the therapeutic effects of tPA in models of ischemic stroke in rodents. Methods Human recombinant tPA (10 mg/kg), alone or in combination with human recombinant 3K3A-APC (2 mg/kg), was given intravenously 4 hours after proximal or distal transient middle cerebral artery occlusion (MCAo) in mice and embolic stroke in rats. 3K3A-APC was additionally administered for 3–4 consecutive days after stroke. The neuropathological and neurological analyses were performed at 1 to 7 days after stroke. Results In all models, tPA alone had no effects on the infarct volume or behavior (i.e., neurological score, foot-fault, forelimb asymmetry, adhesive removal) compared to vehicle. tPA and 3K3A-APC combination therapy reduced the infarct volume 24 hours and 7 days after proximal or distal transient MCAo in mice and 7 days after embolic stroke in rats by 65%, 63% and 52%, respectively, improved significantly (P<0.05) behavior, and eliminated tPA-induced intracerebral microhemorrhages. Conclusions 3K3A-APC extends the therapeutic window of tPA for ischemic stroke in rodents. Therefore, this combination therapy should also be considered for treating stroke in humans.

Activated protein C: biased for translation

“…[109][110][111]116 3K3A-APC was neuroprotective and extended the therapeutic window for tPA. 109 It was neuroprotective when therapy was initiated beginning 4 hours after onset of ischemia and when a repeated bolus dosing regimen was employed. 109,110 3K3A-APC was neuroprotective in the presence of comorbidities exemplified in hypertensive rats or in aging female mice.…”

“…Recombinant human 3K3A-APC was neuroprotective and extended the therapeutic window for tPA. 109 It was neuroprotective when therapy was initiated beginning 4 hours after onset of ischemia and when a repeated bolus dosing regimen was employed.…”

“…109 It was neuroprotective when therapy was initiated beginning 4 hours after onset of ischemia and when a repeated bolus dosing regimen was employed. 109,110 3K3A-APC was neuroprotective in the presence of comorbidities exemplified in hypertensive rats or in aging female mice. 111 Notably, in vivo and in vitro studies showed that 3K3A-APC promoted neurogenesis in the postischemic mouse brain and in human embryo-derived neuroprogenitor cell cultures, respectively.…”

Rapamycin prevents cerebral stroke by modulating apoptosis and autophagy in penumbra in rats

“…Currently, systemic thrombolysis with recombinant intravenous tissue plasminogen activator (rtPA) remains a frequently used therapy which can improve clinical outcome of patients with acute ischemic stroke 3, 4. However, rtPA has an increased risk of hemorrhage beyond a few hours of poststroke, and only less than 4% of stroke patients can benefit from it 5, 6. Therefore, it is urgent to clarify the mechanism of ischemic stroke and explore new potential targeted strategies for the treatment of stroke.…”

Activated protein C β-glycoform promotes enhanced noncanonical PAR1 proteolysis and superior resistance to ischemic injury

“…2 APC engagement with the endothelial cell protein C receptor (EPCR) facilitates proteolysis-dependent activation of proteaseactivated receptor 1 (PAR1), 3 which protects the endothelial cell barrier from disruptive agents, 4 inhibits apoptosis, 5,6 and limits cytokine expression from cells exposed to proinflammatory stimuli. 6,7 Recombinant APC signaling attenuates neurovascular sequelae associated with experimental murine ischemic stroke [8][9][10] and limits neurotoxicity caused by subsequent thrombolytic tissue plasminogen activator (t-PA) administration. 11,12 Recombinant APC therefore represents a promising neuroprotective drug candidate to treat ischemic stroke, and a recombinant nonanticoagulant APC variant is currently being evaluated as an adjunctive therapy to minimize the adverse effects of t-PA administration.…”