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

Astroglial and fibroblast growth factors have neurotrophic functions for cultured peripheral and central nervous system neurons.

“…AGF and FGF, proteins with established mitogenic and differentiation-promoting effects for glial cells and derivatives of mesoderm origin (3)(4)(5)(6)10), were found also to be trophic for neurons cultured from embryonic peripheral and central nervous systems. Neurotrophic actions comprised (i) promotion of survival, (ii) neuritic growth, and (iii) induction of transmitter-synthesizing enzyme ChoAcTase activity.…”

“…Thus, nerve growth factor has been shown to act as a mitogen on rat pheochromocytoma (1) and adrenal medullary chromaffin cells (2). On the other hand, FGF and astroglial growth factors (AGF-1 and -2) that are closely related or even identical to acidic and basic FGF (aFGF, bFGF) (3) induce proliferation and differentiation of neuroectodermal astroglial cells (4), oligodendrocytes (5,6), and neuron-like PC-12 pheochromocytoma cells (7).…”

High molecular weight forms of basic fibroblast growth factor recognized by a new anti‐bFGF antibody

“…In addition, bFGF also influences proliferation and differentiation of glial cells [2,3]. Recently, in vivo and in vitro studies have shown that bFGF exerts neurotrophic actions in the peripheral (PNS) and central nervous system (CNS) [4-g].…”

Primary Cultures of Astrocytes from Different Brain Areas of Newborn Rats and Effects of Basic Fibroblast Growth Factor

“…After 2-3 weeks nearly all cells in these cultures contain glial fibrillary acidic protein (GFAP) [2], Therefore, these cells have been regarded as a uniform population of astroblasts with similar properties. How ever, when the astrocytes were cultured in a chemically defined medium [3,4], they showed a more heterogenous aspect: some cells exhibited a flat and polygonal shape, others were more elongated and extend several protoplasmic processes. Moreover, it has been found that not all cultured astro cytes present glutamine synthetase (GS) [3][4][5], that a small subgroup of astrocytes accumulates glycogen [6] and that only a subpopulation of astrocytes synthesize the proteinase inhibitor a2-macroglobulin [7],…”