DIFFERENTIAL EXPRESSION IN GLIAL-CELLS DERIVED FROM CHICK-EMBRYO CEREBRAL HEMISPHERES AT AN ADVANCED-STAGE OF DEVELOPMENT

Recently, we have characterized glial cultures derived from very early neurogenesis (E3) and found them to consist largely of early glioblas tic or astroblastic cells with the capacity to differentiate into astr ocytes given sufficient time in culture or with advancing age, i.e., c ell passage, This study examines and compares the characteristics of a strocyte-enriched cultures derived from advanced embryonic ages (E15) in the chick embryonic cerebral hemispheres, We report several remarka ble findings, 1) Mature astrocytes (GFAP(+), vimentin(-)) appear as ea rly as 5 days in vitro (DIV) in primary culture (PO). 2) Also apparent in primary cultures were extensive populations of neurons (neurofilam ent(+); NF+) growing atop or in close proximity to mature astrocytes, 3) NF+ neurons disappeared after the first cell passage, and GFAP(+) a strocytes were greatly diminished within two cell passages thereafter, 3) High concentrations of NGF were expressed, presumably by glial cel ls, in primary cultures through 14 DIV, declining to a low plateau thr ough 27 DIV and remaining low, but measurable in subsequent cell passa ges, 4) At later cell passages (>5) immature phenotypes of these same cell types continued to be expressed in E15CH cultures, i.e., positive staining for GFAP and vimentin and GFAP, GS, and NGF can all be detec ted on Western blots, We conclude from these findings that 1) mitotic multipotential neural cells are present within cerebral hemispheres ev en at late stages of development (E15); 2) neuroblasts and astroblasts have a reciprocal relationship requiring the presence of both cell ty pes in order for mature expression of their phenotypes; 3) the NGF pro file parallels the appearance and disappearance of neurons in E15 chic k embryonic cerebral hemisphere primary cultures, strongly suggesting that this trophic factor may be involved in the mutually beneficial re lationship between astrocytes and neurons. (C) 1997 Wiley-Liss, Inc.