A novel rat pup model that recapitulates the clinical phenotype of intraventricular hemorrhage-induced hydrocephalus in human preterm neonates

Hydrocephalus is a disorder that involves accumulation of cerebrospinal fluid (CSF) in the ventricles of the brain. The incidence is significantly higher in preterm neonates, which is highly associated with intraventricular hemorrhage (IVH). The sequela of severe IVH manifests post-hemorrhagic hydrocephalus (PHH) that contributes to neurologic morbidity and mortality in preterm infants. There have been numerous animal models to study the mechanism and progression of hydrocephalus since 1913. However, we still lack an IVH-induced hydrocephalus model that accurately reflects the gestational age of hemorrhage causing hydrocephalus in the preterm neonatal brain. To address this, our study aims to establish a reliable and reproducible pre-clinical model of IVH-induced hydrocephalus using rat pups with the timeframe equivalent to human preterm neonates. To this end, we performed stereotactic injection of lysed red blood cells (RBC), hemoglobin (Hb), or iron (FeCl3) into lateral ventricles of Sprague Dawley rat pups at P2-3 for inducing IVH and determined the level of hydrocephalus by magnetic resonance imaging, scanning electron microscopy, PERLS stain, and neurobehavior assessment. Our results demonstrated RBC and iron induced hydrocephalus characterized by severe ventriculomegaly, domed cranium, ventricular iron deposition, and neurobehavioral deficits whereas Hb and control (saline) did not. RBC and iron also induced denudation of ependymal cilia and deformation of choroid plexus. Thus, we concluded intraventricular free iron is critical to the onset of IVH-induced hydrocephalus in the stage of preterm neonates. This model will be useful in investigating therapeutic targets of hydrocephalus and inspire fine tuning of human in vitro hydrocephalus models.