1 1 . M U C O P O L Y S A C C H A R I D E S IN T I S S U E C U L T U R E
373
between growth rate and polysaccharide production. Small variations
in the glucose concentration, however, do not appear to affect the
rate of mucopolysaccharide synthesis significantly (Morris, 1960).
Factors that influence the production of mucopolysaccharides include
the concentrations of serum and embryo extract in the medium. Thus
stimulation of mucopolysaccharide synthesis by embtyo extract has
been claimed by Grossfeld et al. (1957), whilst a concentration of 5°/o
serum gives optimum production of hyaluronic acid by monolayer
cultures of rat dermal fibroblasts; concentrations above 10°/o, however,
cause marked inhibition (Daniel et al., 1961). This change in the rate of
production of acid mucopolysaccharides does not appear to be associated with any changes in the growth rate. Daniel and Dingle (unpublished observations) have found that occasional batches of horse
serum caused an increased production of hyaluronic acid in cultures
of these cells. This action is unexplained.
There seems to be no conclusive evidence for an effect of pH on the
synthesis of mucopolysaccharides in culture (Morris, 1960), although
the density of the cell population in the culture vessel is not without
influence. Morris (1960) for example, found that when the cells were
crowded there was an inhibition of cell division whilst the specific
production of acid polysaccharides was decreased by more than one
third. This may well be related to the findings of Daniel, Dingle, and
Webb (unpublished observations) that when the cell density in monolayer cultures of rat dermal fibroblasts is increased to more than 2 X 10
5
cells/cm
2 the rate of oxygen uptake is diminished. This change in
metabolism does not appear to be related to any cell degeneration,
nor to lack of nutrients or oxygen, since the cells remain in this
"depressed" state for many hours after removal from the culture
vessel. Both these processes may possibly be related to phenomena such
as those discussed by Abercrombie elsewhere in this volume (see
Chapter 5).
5. The Rate of Acid Mucopolysaccharide Production by Cells in Culture
The results, summarized in Table III, although obtained under
different cultural conditions, and with cells isolated from different
tissues, give some idea of rates of acid mucopolysaccharide production
in tissue culture by isolated cells. The rate of polysaccharide production
varies considerably in different periods of the culture, as shown in
Fig. 1. These results, taken from Daniel et al. (1961) agree with the
observations of Morris (1960) in which the rate of acid mucopolysaccharide production was found to continue undiminished during
intervals of D N A synthesis, but to fall off as the synthesis of D N A
373
between growth rate and polysaccharide production. Small variations
in the glucose concentration, however, do not appear to affect the
rate of mucopolysaccharide synthesis significantly (Morris, 1960).
Factors that influence the production of mucopolysaccharides include
the concentrations of serum and embryo extract in the medium. Thus
stimulation of mucopolysaccharide synthesis by embtyo extract has
been claimed by Grossfeld et al. (1957), whilst a concentration of 5°/o
serum gives optimum production of hyaluronic acid by monolayer
cultures of rat dermal fibroblasts; concentrations above 10°/o, however,
cause marked inhibition (Daniel et al., 1961). This change in the rate of
production of acid mucopolysaccharides does not appear to be associated with any changes in the growth rate. Daniel and Dingle (unpublished observations) have found that occasional batches of horse
serum caused an increased production of hyaluronic acid in cultures
of these cells. This action is unexplained.
There seems to be no conclusive evidence for an effect of pH on the
synthesis of mucopolysaccharides in culture (Morris, 1960), although
the density of the cell population in the culture vessel is not without
influence. Morris (1960) for example, found that when the cells were
crowded there was an inhibition of cell division whilst the specific
production of acid polysaccharides was decreased by more than one
third. This may well be related to the findings of Daniel, Dingle, and
Webb (unpublished observations) that when the cell density in monolayer cultures of rat dermal fibroblasts is increased to more than 2 X 10
5
cells/cm
2 the rate of oxygen uptake is diminished. This change in
metabolism does not appear to be related to any cell degeneration,
nor to lack of nutrients or oxygen, since the cells remain in this
"depressed" state for many hours after removal from the culture
vessel. Both these processes may possibly be related to phenomena such
as those discussed by Abercrombie elsewhere in this volume (see
Chapter 5).
5. The Rate of Acid Mucopolysaccharide Production by Cells in Culture
The results, summarized in Table III, although obtained under
different cultural conditions, and with cells isolated from different
tissues, give some idea of rates of acid mucopolysaccharide production
in tissue culture by isolated cells. The rate of polysaccharide production
varies considerably in different periods of the culture, as shown in
Fig. 1. These results, taken from Daniel et al. (1961) agree with the
observations of Morris (1960) in which the rate of acid mucopolysaccharide production was found to continue undiminished during
intervals of D N A synthesis, but to fall off as the synthesis of D N A