Neuroprotective effect of heparin Trisulfated disaccharide on ischemic stroke

Cells undergoing hypoxia experience intense cytoplasmic calcium (Ca²⁺) overload. High concentrations of intracellular calcium ([Ca²⁺]_i) can trigger cell death in the neural tissue, a hallmark of stroke. Neural Ca²⁺ homeostasis involves regulation by the Na⁺/Ca²⁺ exchanger (NCX). Previous data published by our group showed that a product of the enzymatic depolymerization of heparin by heparinase, the unsaturated trisulfated disaccharide (TD; ΔU, 2S-GlcNS, 6S), can accelerate Na⁺/Ca²⁺ exchange via NCX, in hepatocytes and aorta vascular smooth muscle cells. Thus, the objective of this work was to verify whether TD could act as a neuroprotective agent able to prevent neuronal cell death by reducing [Ca²⁺]_i. Pretreatment of N2a cells with TD reduced [Ca^2+]_i rise induced by thapsigargin and increased cell viability under [Ca^2+]_I overload conditions and in hypoxia. Using a murine model of stroke, we observed that pretreatment with TD decreased cerebral infarct volume and cell death. However, when mice received KB-R7943, an NCX blocker, the neuroprotective effect of TD was abolished, strongly suggesting that this neuroprotection requires a functional NCX to happen. Thus, we propose TD-NCX as a new therapeutic axis for the prevention of neuronal death induced by [Ca²⁺]_i overload.