Subpopulation of nestin positive glial precursor cells occur in primary adult human brain cultures

Glial fibrillary acidic protein (GFAP) is an intermediate filament protein considered to be the best astroglial marker. However, the predominant cell population in adult human brain tissue cultures does not express GFAP; these cells have been termed "glia-like" cells. The basic question about histological origin of adult human brain cultures remains unanswered. Some authors showed that "glia-like" cells in adult human brain cultures might be of non-glial origin. We examined primary explant tissue cultures derived from 70 adult human brain biopsies. Within first 5-10 days approximately 5-10% of the small explants became attached. Outgrowing cells were mostly flat cells. These cells formed confluent layer over 3-6 weeks in culture. At confluence the cultures contained 2-5% of microglial cells, 0.1% GFAP-positive astrocytes, less than 0.01% oligodendrocytes and 95-98% GFAP-negative "glia-like" cells. This population of flat "glia-like" cells was positively stained for vimentin, fibronectin, and 20-30% of these cells stained for nestin. Our findings revealed that 1 mM dibutyryl-cAMP addition, in serum free conditions, induced a reversible stellation in 5-10% of the flat "glia-like" cells but did not induce the expression of GFAP or nestin in morphologically changed stellate cells. These results demonstrate that "glia-like" cells in primary adult human brain cultures constitute heterogeneous cell populations albeit with similar morphological features. Two distinct subpopulations have been shown: (i) the one immunostained for nestin; and (ii) the other reactive for dibutyryl-cAMP treatment.