Object-based analysis of astroglial reaction and astrocyte subtype morphology after ischemic brain injury.

Reactive astrogliosis following brain damage is characterized by specific alterations of astrocyte phenotype and function. This response can be roughly categorized into two major patterns (Sofroniew and Vinters 2010). In the context of brain inflammation, or remote from focal lesions, astrocytes show mild to moderate responses characterized by hypertrophy of cell soma and processes and an upregulation of intermediary filaments, but preserved individual domains (Wilhelmsson et al. 2006). The impact of those changes is not fully understood, but they may be associated with pro-regenerative properties (Liberto et al. 2004). In regions of serious brain damage, reactive astrogliosis is additionally characterized by interlacing processes, cellular proliferation and the disruption of individual domains. Genetic ablation of reactive astrocytes showed that the latter process is vital for the restriction of the adverse inflammatory environment present after spinal cord injury, stroke and other causes of central nervous system damage (Okada et al. 2006, Sofroniew and Vinters 2010, Shimada et al. 2011). In contrast, the chronic sequelae of glial scarring imply a regenerative failure owing to an inhibiting environment for axonal and synaptic plasticity (Menet et al. 2003, Silver and Miller 2004). Hence, reactive astrogliosis may have ambivalent effects depending on where and when it occurs. Object-based analysis of astroglial reaction and astrocyte subtype morphology after ischemic brain injury