The anchorage-dependent cell line, MRC-5, was cultivated successfully on glass fibers with diameters ranging from 24 to 120 mum, despite vast differences in substrate curvature. Multilayer cell growth was observed, particularly for fiber diameters 30 mum and below, which differed from the typical monolayer growth observed in T-flask cultivations. Cells were maintainable at a reduced incubation temperature and were demonstrated to support virus replication for the 21-day antigen production period. Direct microscopic observation, along with indirect calculations, indicated that only a small fraction (about 10%) of the total available fiber surface area was occupied by cells. Thus, productivity per unit surface area was replaced by productivity per unit medium volume when evaluating fiber bed performance. Antigen and protein yields, as well as nutrient uptakes, were 1.5- to 2.5-fold greater than parallel T-flask cultures when compared on this basis. Corresponding available surface area-based values were 10- to 15-fold lower for the fiber bed reactor. The multilayer cell morphology obtained in the fiber bed was attractive for antigen production when immobilized in a column reactor system. (C) 1993 John Wile & Sons, Inc.
