Prophylactic neuroprotection against stroke: low-dose, prolonged treatment with deferoxamine or deferasirox establishes prolonged neuroprotection independent of HIF-1 function

Prophylactic neuroprotection against stroke could reduce stroke burden in thousands of patients at high risk of stroke, including those with recent transient ischemic attacks (TIAs). Prolyl hydroxylase inhibitors (PHIs), such as deferoxamine (DFO), reduce stroke volume when administered at high doses in the peristroke period, which is largely mediated by the hypoxia-inducible transcription factor (HIF-1). Yet, in vitro experiments suggest that PHIs may also induce neuroprotection independent of HIF-1. In this study, we examine chronic, prophylactic, low-dose treatment with DFO, or another iron chelator deferasirox (DFR), to determine whether they are neuroprotective with this paradigm and mediate their effects through a HIF-1-dependent mechanism. In fact, prophylactic administration of low-dose DFO or DFR significantly reduces stroke volume. Surprisingly, DFO remained neuroprotective in mice haploinsufficient for HIF-1 (HIF-1 +/-) and transgenic mice with conditional loss of HIF-1 function in neurons and astrocytes. Similarly, DFR was neuroprotective in HIF-1 +/- mice. Neither DFO nor DFR induced expression of HIF-1 targets. Thus, low-dose chronic administration of DFO or DFR induced a prolonged neuroprotective state independent of HIF-1 function. As DFR is an orally administered and well-tolerated medication in clinical use, it has promise for prophylaxis against stroke in patients at high risk of stroke. Journal of Cerebral Blood Flow & Metabolism (2011) 31, 1412-1423; doi:10.1038/jcbfm.2010.230; published online 1( January 2011