Morphological and biochemical maturation of rat astroglial cells grown in a chemically defined medium: Influence of an astroglial growth factor

The results indicate that astroglial cells undergo limited maturation in the chemically defined medium and that this process is positively affected by the astrogLial growth factor.

Abstract

Astroglial cells from cerebral hemispheres of newborn rats were cultured for 5 days in Waymouth's MD 705/1 medium containing 10% fetal calf serum. Thereafter, cells were grown in a chemically defined medium consisting of basal Waymouth's medium supplemented with insulin (5 μg/ml) and fatty acid free bovine serum albumin (0.5 mg/ml). The cells underwent morphological and biochemical development over a period of 28 days. The changes in the amount of glial fibrillary acidic protein indicated a development of gliofilaments. The level of S100 protein increased during the entire culture period, while glutamine synthetase activity remained low and relatively constant. The addition of an astroglial growth factor, partially purified from bovine brain soluble extract, stimulated the morphological maturation of the astroglial cells. The cells extended cytoplasmic processes and resembled mature astrocytes. At the ultrastructural level an increase in free ribosomes was observed and the intermediate filaments became organized into large bundles. The amount of glial fibrillary acidic protein was not significantly increased, but the level of S100 protein and the glutamine synthetase activity were greatly enhanced. Our results indicate that astroglial cells undergo limited maturation in the chemically defined medium and that this process is positively affected by the astroglial growth factor.