GFAP-positive astrocytes are rare or absent in primary adult human brain tissue cultures

Abstract

Traditionally, astrocytes are divided into fibrous and protoplasmic types based on their morphologic appearance. Here the cultures were prepared separately from the adult human cortical gray and white matter of brain biopsies. Both cultures differed only in the number of glial fibrillary acidic protein (GFAP)-positive cells. In the gray matter these were absent or rare, whereas in confluent cultures from the white matter they reached 0.1% of all cells. Three main morphologic types of GFAP-positive cells were found in this study: stellate, bipolar and large flat cells. GFAP-positive cells with two or three long processes mimic a neuron-like morphology. We did not find process-bearing cells expressing neuronal markers (MAP-2, NF, and N-CAM). The conflicting reports concerning GFAP immunostaining and the study dealing with the presence of putative neurons in adult human brain cultures are discussed with respect to these findings. The latter classification of astrocytes into type 1 and type 2 is based on immunostaining to A2B5 antigen: type 1 (GFAP+/A2B5-) and type 2 (GFAP+/A2B5+) astrocytes are proposed to be analogous to protoplasmic and fibrous astrocytes, respectively. In adult human brain cultures we found only small amount of A2B5-positive cells. Double immunofluorescence revealed that astroglial cells of similar fibrous or bipolar shape grown on one coverslip were either GFAP+/A2B5+ or GFAP+/A2B5-. On the other hand, the A2B5+/GFAP-immunophenotype was not observed. These results indicate that in general the cell phenotype from adult human brain tissue is not well established when they are in culture.

Small-molecule screen reveals pathways that regulate C4 secretion in stem cell-derived astrocytes

“…Of note, this protocol is robust and reproducible when applied across pluripotent iPSC and ESC lines. Only a small percentage of differentiated cells expressed glial fibrillary acidic protein (GFAP) and primarily appear to be “resting astrocytes.” As reported previously, GFAP is heterogeneously expressed in the human brain and is primarily associated with reactive states in disease ( DeSilva et al., 2012 ; Liddelow et al., 2017 ; Lundin et al., 2018 ; Macikova et al., 2009 ; Tcw et al., 2017 ).…”

Astroglial differentiation of fibronectin‑positive human “glia-like” cells

“…In all cultures, we observed mainly stellate GFAP-positive cells which may correspond to fi brous astrocytes, however, no morphologies of protoplasmic astrocytes. On the other hand, large fl at and bipolar GFAP-positive cells occurred in cultures that were not observed in adult human brain tissue (3). Bipolar GFAP-positive and neuronal marker-negative stained cells were also present, as described by Davies (4).…”

Physiological and Pathological Ageing of Astrocytes in the Human Brain

“…Likewise, other astrocyte markers present regional variation. For example, cortical astrocytes express relative high levels of ALDH1L1 and low levels of GFAP [ 17 , 18 ]. Still, GFAP is often used as the golden standard to identify astrocytes, but region-specific expression patterns indicate that a proportion of astrocytes is missed if only GFAP as a marker is used.…”