Single cell RNA-seq transcriptomic profile of circulating immune and progenitor cells in a mouse model of neonatal hypoxic/ischemic (HI) brain damage.

Hematopoietic cells play a pivotal role in regulating the inflammatory and reparative immune responses triggered after ischemic tissue damage. The response initiated within the injured tissue leads to compositional and transcriptional changes in circulating hematopoietic and progenitor cells, which have been utilized as biomarkers. While the importance of different immune and progenitor cell subtypes in the development of ischemic damage has been extensively researched in adult tissue injuries, there has been limited investigation in neonates. This is a critical developmental stage where ischemic damage can result in severe and irreversible health consequences if not promptly treated. To determine how ischemic damage could affect circulating cells in neonates, we have induced hypoxic-ischemic (HI) brain damage in seven-day-old mice, characterized by focal white and gray-matter injury (Rice-Vannucci model). Brain damage and circulating cells were analyzed at 48h post-HI, the intermediate reparative/inflammatory response phase post-injury.  We applied scRNAseq to dissect the transcriptional and cellular composition changes in the peripheral blood of HI-treated and SHAM control neonates. This study provides the first scRNAseq dataset for immune and progenitor circulating cells in newborns with cerebral HI damage. It may help to identify biomarkers and selective therapeutic approaches aimed at modulating inflammatory and reparative pathways. 
CD1 postnatal day 7 (P7) mice were subjected to   hypoxic/ischemic (HI) brain injury by permanent ligation of the left common carotid artery followed, after 2h recover, by relocation to  a hypoxia chamber for 90 minutes. Sham control mice (SHAM) underwent a skin incision and wound closure followed by hypoxia exposure.  Circulating blood cells were collected from SHAM and HI mice at P9. After red blood cells (RBC) lysis, 7AAD-Ter119- cells were FACS sorted and analysed using sc RNAseq. Other samples were FACS sorted for CD45+CD11+ and CD45-CD31+ cells and mixed.