RNAseq profiling of primary microglia and astrocyte cultures in near-term ovine fetus: A glial in vivo-in vitro multi-hit paradigm in large mammalian brain

Background: The chronically instrumented fetal sheep is a widely used animal model to study fetal brain development in health and disease, but no methods exist yet to interrogate dedicated brain cell populations to identify their molecular and genomic phenotype. For example, the molecular mechanisms whereby microglia or astrocytes contribute to inflammation in the brain remain incompletely understood. New method: Here we present a protocol to derive primary pure microglial or astrocyte cultures from near -term fetal sheep brain, after the animals have been chronically instrumented and studied in vivo. Next, we present the implementation of whole transcriptome sequencing (RNAseq) pipeline to deeper elucidate the phenotype of such primary sheep brain glial cultures. Results: We validate the new primary cultures method for cell purity and test the function of the glial cells on protein (IL-1 beta) and transcriptome (RNAseq) levels in response to a lipopolysaccharide (LPS) challenge in vitro. Comparison with existing methods: This method represents the first implementation of pure microglial or astrocytes cultures in fetal sheep brain. Conclusions: The presented approach opens new possibilities for testing not only supernatant protein levels in response to an in vitro challenge, but also to evaluate changes in the transcriptome of glial cells derived from a large mammalian brain bearing high resemblance to the human brain. Moreover, the presented approach lends itself to modeling the complex multi-hit paradigms of antenatal and perinatal cerebral insults in vivo and in vitro. (C) 2016 Elsevier B.V. All rights reserved.