3K3A-activated protein C stimulates postischemic neuronal repair by human neural stem cells in mice

Activated protein C (APC) is a blood protease with anticoagulant activity and cell-signaling activities mediated by activation of protease-activated receptors 1 and 3 (PAR1, PAR3) via non-canonical cleavage(1). Recombinant APC and/or its analogs with reduced (>90%) anticoagulant activity such as 3K3A-APC (Lys191–193Ala), engineered to reduce APC-associated bleeding risk while retaining normal cell signaling activity, have shown benefits in preclinical models of ischemic stroke(2–6), brain trauma(7), multiple sclerosis(8), amyotrophic lateral sclerosis(9), sepsis(10,11), ischemic/reperfusion injury of heart(12), kidney and liver(13), pulmonary, kidney and gastrointestinal inflammation(1,11), diabetes(14) and lethal body radiation(15). Based on proof of concept studies and an excellent safety profile in humans, 3K3A-APC has advanced to clinical trials as a neuroprotectant in ischemic stroke(16,17). Recently, 3K3A-APC has been shown to stimulate neuronal production by human neural stem/progenitor cells (NSCs) in vitro(18) via a PAR1-PAR3-sphingosine-1-phosphate receptor 1-Akt pathway(19), suggesting the potential for APC-based treatment as a strategy for structural repair in the human central nervous system. Here, we report that late post-ischemic treatment of mice with 3K3A-APC stimulates neuronal production by transplanted human NSCs, promotes circuit restoration, and improves functional recovery. Thus, 3K3A-APC-potentiated neuronal recruitment from engrafted NSCs may offer a new approach to the treatment of stroke and related neurological disorders