Cell permeant peptidomimetics to prevent delayed vasospasm and neurological deficits after subarachnoid hemorrhage

PROJECT SUMMARYSubarachnoid hemorrhage (SAH) due to rupture of an intracranial aneurysm leads to delayed vasospasm resulting in neuroischemia (stroke). The overall morbidity (profound neurologic deficit in 10-20% of survivors) and mortality (50%) are high, and the disease affects a relatively young adult population. Therapeutic options to prevent delayed vasospasm and neuroischemia after SAH are currently limited to hemodynamic optimization and nimodipine, which have marginal clinical efficacy. Thus, treatment of delayed vasospasm after SAH represents an unmet clinical need in an orphan population with severe clinical consequences.Attempts to treat SAH-induced vasospasm with existing vasodilators often fail because of systemic hypotension (leading to decreased cerebral perfusion) and a cerebral vasculature that is refractory to activation of nitric oxide (NO)-dependent signaling pathways.5 NO signaling modulates vascular smooth muscle (VSM) relaxation and regulation of cerebral blood flow. The impaired response of cerebral vessels to vasodilators, i.e. impaired vasorelaxation after SAH, is likely due to down regulation of the signaling elements in the NO pathway after SAH. The hypothesis of this investigation is that treatment with a rationally designed, cell permeant phosphopeptide mimetic of a downstream effector protein of the NO pathway will bypass downregulated signaling elements, restore vasorelaxation, and prevent delayed vasospasm after SAH. This approach is more targeted and stoichiometric than approaches that activate or inhibit receptors or enzymes. In addition, this approach is particularly useful in SAH where preventing systemic hypotension and optimizing cerebral vasodilation is paramount.A family of cell permeant phosphopeptide analogues of a substrate of cGMP-dependent Protein Kinase (PKG), and an actin-associated protein that modulates VSM relaxation, were rationally designed and synthesized. Three candidate peptides were demonstrated to directly relax intact VSM in ex vivo bioactivity assays. The peptide with the shortest sequence (denoted as VP3) and strongest bioactivity was chosen as the optimal peptide for use to determine in vivo efficacy.Rupture of intracranial aneurysms leads to subarachnoid hemorrhage which is associated with delayed vasospasm, leading to neuroischemic events (stroke) and neurobehavioral deficits, and current therapeutic options are limited and only minimally effective. This project will determine the efficacy of cell permeant therapeutic molecules in preventing delayed vasospasm and improving functional outcomes after SAH in a rat model. These studies will identify and de-risk a lead candidate molecule to advance for further pre-clinical studies to offer novel translatable therapeutic approaches to prevent debilitating clinical sequelae of SAH-induced vasospasm.