Intracerebral hemorrhage (ICH) is a serious medical condition caused by bleeding in the brain. It should be noted that at the last AHA/ASA International Stroke Conference in Feb. 2019, findings were presented from a Phase III trial showing that deferoxamine (DFO) was futile against ICH. One potential explanation is that DFO does not cross the BBB, and it has significant toxicity issues. Thus, the main focus now is to determine the efficacy and therapeutic window of a novel, safe, and effective therapy against ICH by testing unique brain penetrant iron chelators. To achieve this goal, and based on the literature and our preliminary data, we will test potent and selective iron chelators such as HBED, and their efficacy will be compared to other iron chelators such as the DADMDFT analog and DFO. After intracranial bleeding, red blood cells lyse and release large amounts of hemoglobin (Hb). These have to be actively phagocytosed, after which the heme (which cannot be recycled) gets degraded to generate iron intracellularly. Under normal physiological conditions, iron homeostasis should be maintained; however, when there are too many (heme) substrates, there is also too much iron, a process called iron dyshomeostasis. Our overall hypothesis is that a lipophilic brain penetrant iron chelator would be effective against ICH. Notably, HBED also has a much better safety profile compared to DFO, which was noted after a thorough Phase I safety trial. We observed that HBED was most potent after a traumatic brain injury model. Also, we found that DADMDFT provides benefits by improving functional and anatomical outcomes in the stroma-free Hb injection model. Besides binding iron, HBED binds ferrous (toxic) iron and converts it into ferric (nontoxic) iron in cells and mitochondria, preventing prooxidant and proinflammatory cascades.
Aim 1 is to investigate the efficacy of HBED over DADMDFT and DFO in improving neurobehavioral and anatomical outcomes after ICH. We will determine and compare the optimal dose-response and therapeutic window of HBED, DADMDFT, and DFO in adult male mice and in parallel in females.
Aims 2, 3, and 4 are to investigate the importance of the known phagocytic receptors CD36 and CD163 for RBCs and Hb, respectively, using the autologous blood ICH preclinical model. We will use the single and double knockouts (versus matched C57BL/6 littermates) that we have already generated. The goal is to understand mechanistically the respective role of these phagocytic receptors because they should participate in the clearance of RBCs and hemoglobin and test the added benefits of the optimal iron chelator, helping to limit the oxidative/inflammatory stress cascades. Toxicity will be monitored, along with brain and serum iron levels over time, after treatment with the iron chelator. This project is timely, and we believe we have assembled a unique team with the tools, animals, models, and expertise necessary to rigorously perform these experiments. We are confident that we can accomplish the proposed aims to inform our stroke partners, allowing them to design a rigorous clinical trial.
Intracerebral hemorrhage (ICH) is the most devastating form of stroke with 30% to 65% mortality and poor prognosis; treatment therapies are mostly nonexistent, and bleeding in the brain leads to hematoma formation, RBC lysis, and the release of hemoglobin, subsequently leading to iron dyshomeostasis. Thus, we plan to compare the effectiveness of unique brain penetrant iron chelators such as HBED and DADMDFT to DFO in wildtype littermates and in CD36-/-, CD163-/-, and CD36-/-CD163-/- to better understand the etiopathology of ICH in these receptors and search for better therapeutic targets.
