Interaction of vitronectin with collagen.

Purified human plasma vitronectin was demonstrated to bind to type I collagen immobilized on plastic as measured by enzyme-linked immunosorbent assay and by binding of 125I-radiolabeled vitronectin to a collagen-coated plastic surface. Vitronectin did not bind to immobilized laminin, fibronectin, or albumin in these assays. Vitronectin showed similar interaction with all types of collagen (I, II, III, IV, V, and VI) tested.

Alternative surfaces for microcarrier culture of animal cells.

As part of an effort to broaden the applicability and efficiency of microcarrier cell culture various alternative new microcarriers were synthesized. The microcarriers were compared as substrates for the growth of several types of cells and with respect to binding of proteins from the culture medium. Cross-linked dextran has been found to be the most suitable material for a microcarrier matrix and was used as the matrix for the new microcarriers.

The separation of harvested cells from microcarriers: a comparison of methods.

Two techniques are described which have been designed to separate harvested cells from microcarriers. The requirements of efficient recovery and high viability of the cells are met by both procedures. Differences both in size and density between cells and microcarriers allow separations which are based on differential centrifugation or filtration.

The use of Cytodex 3 microcarriers and reduced-serum media for the production of nerve growth promoters from chicken heart cells.

Microcarrier cell culture provides an efficient method for the production of cell products. Cytodex 3 microcarriers were used for the production of an active nerve growth-promoting substance from chicken heart fibroblasts (1 degree -4 degrees cultures). Such cells release into culture medium a factor which stimulates the growth of nerve fibres from explanted ciliary, sympathetic and spinal neurons.

Harvesting and subculturing cells growing on denatured-collagen coated microcarriers (Cytodex 3).

Selecting correct procedures and conditions for harvesting cells was essential for successful subcultivation of cells when using the microcarrier culture technique. The proteolytic enzymes trypsin, Dispase and collagenase were compared with respect to the yield and the viability of Vero cells when harvested from Cytodex 3 microcarriers. Treatment with Dispase or trypsin resulted in similar viabilities but recovery after trypsin treatment was improved.

Alternative surfaces for microcarrier culture of animal cells.

As part of an effort to broaden the applicability and efficiency of microcarrier cell culture various alternative new microcarriers were synthesized. The microcarriers were compared as substrates for the growth of several types of cells and with respect to binding of proteins from the culture medium. Cross-linked dextran has been found to be the most suitable material for a microcarrier matrix and was used as the matrix for the new microcarriers.

Serum supplements and serum-free media: applicability for microcarrier culture of animal cells.

Several different combinations of serum supplements and also serum-free media were examined for their ability to support the growth of MRC-5 and Vero cells on Cytodex microcarriers. Greater economy of serum was achieved for routine microcarrier culture by selecting the type of serum supplement, on the basis of whether the supplement was to support attachment and growth of cells at low densities or growth of cells at later stages in the culture cycle. Further economy was achieved by altering the serum concentration according to the requirements of each stage of the culture cycle.

A comparison of various laboratory scale culture configurations for microcarrier culture of animal cells.

When developing procedures for microcarrier culture it is important to use equipment which results in even suspension of microcarriers with minimal shear forces and which permits maximum growth of the culture. A variety of different laboratory scale culture systems were investigated including traditional magnetic spinner flasks, modified spinner flasks, cultures stirred with bulb-shaped rods and a fluid lift culture system. All systems were compared with respect to growth of either MRC-5 or Vero cells on Cytodex microcarriers.

Critical parameters in the microcarrier culture of animal cells.

The successful culture of over 60 different cell types on Cytodex TM1 microcarriers has enabled identification of parameters critical for obtaining high cell yields from microcarrier cultures. Careful control of the initial phase of microcarrier culture was found to be critical. Increasing cell density, reducing culture volume and reducing stirring rate during the initial phase all assisted in improving cell yields.

Spectroscopic evidence for the formation of a 4-keto intermediate in the UDP-apiose/UDP-xylose synthase reaction.

Uridine diphospho-D-glucose (UDP-Glc) and UDP-methyl-D-glucuronate (UDP-GlcUAMe) have been shown to be competitive inhibitors for the UDP-apiose/udp-xylose synthase from cell suspension cultures of parsley. The apparent Ki values for these substrate analogues were of the same order of magnitude as the apparent Km value for the substrate UDP-D-glucuronic acid (UDP-GlcUA). The difference spectrum of the incubation mixture containing UDP-GlcUA, NAD+ and the highly purified enzyme showed a transient absorption with a maximum at 292 nm which disappeared upon addition of sodium hydroxide.