Mouse Models of Periventricular Leukomalacia

Abstract

We describe a protocol for establishing mouse models of periventricular leukomalacia (PVL). PVL is the predominant form of brain injury in premature infants and the most common antecedent of cerebral palsy. PVL is characterized by periventricular white matter damage with prominent oligodendroglial injury. Hypoxia/ischemia with or without systemic infection/inflammation are the primary causes of PVL. We use P6 mice to create models of neonatal brain injury by the induction of hypoxia/ischemia with or without systemic infection/inflammation with unilateral carotid ligation followed by exposure to hypoxia with or without injection of the endotoxin lipopolysaccharide (LPS). Immunohistochemistry of myelin basic protein (MBP) or O1 and electron microscopic examination show prominent myelin loss in cerebral white matter with additional damage to the hippocampus and thalamus. Establishment of mouse models of PVL will greatly facilitate the study of disease pathogenesis using available transgenic mouse strains, conduction of drug trials in a relatively high throughput manner to identify candidate therapeutic agents, and testing of stem cell transplantation using immunodeficiency mouse strains. Video LinkThe video component of this article can be found at http://www.jove.com/video/1951/ ProtocolDetailed procedures of creating neonatal brain injury in P6 mice:1. Postnatal day 6 (P6) mice are anesthetized with indirect cooling on ice to the point of unresponsiveness to noxious stimulation (deep anesthesia). 2. Following cleaning the skin with alcohol, a midline ventral incision is made in the anterior neck. 3. Under a dissecting microscope, the bifurcation of the right common carotid artery is approached by gently retracting the omohyoid and sternocleidomastoid muscles. 4. The fascia around the carotid sheath is removed, and the proximal internal branch isolated from the nearby vagus nerve and sympathetic ganglia with a hook. The internal carotid artery is then cauterized using a cauterizing tip. 5. Following cauterization, the skin incision is sutured, and the animal is kept warm until fully awake and then returned to the dam. 6. One hour after ligation, the animal is placed in a sealed chamber infused with nitrogen until a level of 6.0% O 2 is reached. The animal is then exposed to 35 min of hypoxia. 7. After hypoxia exposure, the mouse recovers on a heating pad (33°C) for 30 min and then is returned to the dam. For creation of brain injury with combined hypoxia/ischemia and infection/inflammation, the animal is then injected intraperitoneally with 0.015 ml of lipopolysaccharide (LPS, 1 mg/kg). 8. Four days post-hypoxia/ischemia, mice are anesthetized with indirect cooling on ice to the point of unresponsiveness to noxious stimuli, then perfused with saline and then 4% paraformaldehyde. Brains are removed and cryoprotected.

Thalamic changes in a preterm sample with periventricular leukomalacia: correlation with white-matter integrity and cognitive outcome at school age

“…These MRI studies performed in heterogeneous groups of preterm children used different quantitative methodologies and reported cortical and subcortical GM volume decreases in infancy (1,17,18), childhood (19,20), or adolescence (21). Thalamic damage is also a common finding in PVL neuropathological studies (2,8), as well as MRI studies (6,7) and PVL mouse models (22). Moreover, quantitation of neuronal loss in a PVL postmortem study showed that the most affected GM structure was the thalamus, with a 38% loss that surpassed the 21% found in the cerebral cortex (2).…”

Magnesium sulphate induces preconditioning in preterm rodent models of cerebral hypoxia‐ischemia

“…The etiology behind brain lesions in preterm infants is multifactorial and partly unknown but most likely includes infection/inflammation, hyperoxia, hypoxia, ischemia, excitotoxicity and injury secondary to IVH/PVH (Favrais et al, 2011; Hagberg et al, 2002; Volpe 2009b). In order to model HI in animals corresponding to the human at preterm, the Rice‐Vannucci model has been adapted to younger animals including PND 5 (Albertsson et al, 2014), PND 6 (Shen et al, 2010) and PND 7 mice as well as PND 3 rats (Sizonenko et al, 2003).…”

Human iPSC-Derived Immature Astroglia Promote Oligodendrogenesis by Increasing TIMP-1 Secretion

“…To facilitate survival of transplanted cells, we induced insults in P6 Rag1 −/− immunodeficient mice using unilateral carotid ligation followed with hypoxia, which resulted in selective injury to the subcortical white matter, without detectable injury to cortical neurons (Liu et al, 2011a; Shen et al, 2010). Consistent with our previous studies (Liu et al, 2011a; Shen et al, 2010), we observed reactive astrogliosis at 4 days after induction of PVL injury selectively in the ipsilateral side of the brain (Fig. S4A–C).…”

“…5A). Immature hiPSC-Astros were grafted to the periventricular area adjacent to the corpus callosum (CC) where hypo-myelination was observed (Liu et al, 2011a; Shen et al, 2010) (Fig. 5B).…”