We have established a permanent cell line (CG-4) of rat central nervous system glial precursors from primary cultures of bipotential oligodendrocyte-type 2-astrocyte (O-2A) progenitor cells, which were kept proliferating with the mitogen(s) secreted by the neuronal B104 cell line. The CG-4 cells have a normal karyotype and display the properties of normal O-2A cells. CG-4 cells can be propagated in serum-free culture medium supplemented with medium conditioned by B104 cells for unrestricted periods of time as O-2A cells, characterized by the presence of the A2B5 surface marker and the absence of markers specific for oligodendrocytes (galactocerebroside, myelin basic protein) or type 2-astrocytes (glial acidic fibrillary protein). bFGF and PDGF are potent mitogens for CG-4 cells and their combination can substitute for the B104-derived mitogen(s). CG-4 cells are capable of differentiating into either oligodendrocytes or type 2-astrocytes. Differentiation into oligodendrocytes occurs after withdrawal of the mitogen. Replacement of the mitogen with fetal calf serum (20%), in contrast, induces 50% of the CG-4 cells to differentiate into type 2-astrocytes. Pure cultures of oligodendrocytes or type 2-astrocytes can be generated in substantial amounts from CG-4 cells and maintained for several weeks in medium containing 5% fetal calf serum.

ObjectiveTo describe a novel case of coronavirus disease 2019 (COVID-19)-associated acute necrotizing encephalopathy (ANE) in a patient with aplastic anemia where there was early brain stem-predominant involvement.MethodsEvaluation of cause, clinical symptoms, and treatment response.ResultsA 59-year-old woman with a background of transfusion-dependent aplastic anemia presented with seizures and reduced level of consciousness 10 days after the onset of subjective fever, cough, and headache. Nasopharyngeal swab testing for severe acute respiratory syndrome coronavirus (SARS-CoV-2) was positive, and CT during admission demonstrated diffuse swelling of the brain stem. She required intubation and mechanical ventilation for airway protection, given her reduced level of consciousness. The patient's condition deteriorated, and MRI on day 6 demonstrated worsening brain stem swelling with symmetrical hemorrhagic lesions in the brain stem, amygdalae, putamina, and thalamic nuclei. Appearances were consistent with hemorrhagic ANE with early brain stem involvement. The patient showed no response to steroid therapy and died on the eighth day of admission.ConclusionsCOVID-19 may be associated with an acute severe encephalopathy and, in this case, was considered most likely to represent an immune-mediated phenomenon. As the pandemic continues, we anticipate that the spectrum of neurologic presentation will broaden. It will be important to delineate the full clinical range of emergent COVID-19-related neurologic disease.