Unbiased Quantitative Single-Cell Morphometric Analysis to Identify Microglia Reactivity in Developmental Brain Injury

• Published in: Life (Basel, Switzerland) Vol. 13; no. 4; p. 899
• Main Authors: St Pierre, Mark, Duck, Sarah Ann, Nazareth, Michelle, Fung, Camille, Jantzie, Lauren L, Chavez-Valdez, Raul
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 28.03.2023; MDPI
• Subjects: 3D rendering; Algorithms; Astrocytes; Brain; Brain injury; Chorioamnionitis; Computational geometry; convex hull; Convexity; Ethanol; Experiments; Head injuries; Hypoxia; Imaris; immune cells; Inflammation; Injuries; Injury analysis; Injury prevention; Ischemia; Laboratories; Machine learning; Mathematical analysis; Microglia; Microscopy; Morphology; Neonates; Sholl intersections; Software; Traumatic brain injury; United States; United States > US; Imaris; sphericity; 3D rendering; Sholl intersections; intrauterine growth restriction; immune cells; chorioamnionitis; convex hull; microglia; neonatal hypoxia–ischemia
• ISSN: 2075-1729; 2075-1729
• DOI: 10.3390/life13040899

Microglia morphological studies have been limited to the process of reviewing the most common characteristics of a group of cells to conclude the likelihood of a "pathological" milieu. We have developed an Imaris-software-based analytical pipeline to address selection and operator biases, enabling use of highly reproducible machine-learning algorithms to quantify at single-cell resolution differences between groups. We hypothesized that this analytical pipeline improved our ability to detect subtle yet important differences between groups. Thus, we studied the temporal changes in Iba1 microglia-like cell (MCL) populations in the CA1 between P10-P11 and P18-P19 in response to intrauterine growth restriction (IUGR) at E12.5 in mice, chorioamnionitis (chorio) at E18 in rats and neonatal hypoxia-ischemia (HI) at P10 in mice. Sholl and convex hull analyses differentiate stages of maturation of Iba1 MLCs. At P10-P11, IUGR or HI MLCs were more prominently 'ameboid', while chorio MLCs were hyper-ramified compared to sham. At P18-P19, HI MLCs remained persistently 'ameboid' to 'transitional'. Thus, we conclude that this unbiased analytical pipeline, which can be adjusted to other brain cells (i.e., astrocytes), improves sensitivity to detect previously elusive morphological changes known to promote specific inflammatory milieu and lead to worse outcomes and therapeutic responses.