IHC analysis of the location and expression patterns of specific biomarkers, such as glial fibrillary acidic protein (GFAP) or S100 calcium-binding protein B (S100β), for the polymorphous astrocyte subgroups is crucial for exploring their multifunctionality in neural tissues under different conditions in vivo, such as progression of neuroinflammation associated with acute ischemic stroke, brain edema-eliciting diseases, traumatic brain injury, psychiatric disorders, or neurodegeneration [159,160,161]. The gene discussed is GFAP; the disease is brain edema.