3. C O N S T R U C T I O N A N D USE OF S Y N T H E T I C M E D I A
105
found to promote adhesion of HeLa, clone S3-Y, cells. Certain formulations of glass were better than others, and treatment with N a O H
improved the adhesive qualities of some of the less satisfactory glass
surfaces. Strain-L mouse connective-tissue cells differ from the HeLa
strain of human cervical carcinoma in excreting protons at a lower
rate, and can attach to surfaces of lower total negative charge. These
aspects of the total environment are highly important for the success
or failure of cultivation of cells in defined media. In stationary cultures,
adhesion of cells to glass is often, though not always, a prerequisite for
subsequent cell division. In suspension, "protective" macromolecules
appear to play a role (cf. Swim and Parker, 1960; Bryant, Schilling,
Earle and Evans, 1960; Bryant, Evans, Schilling and Earle, 1961).
It is still today a widespread practice to supplement synthetic media
with small amounts (20°/o and downwards) of serum, dialysates or
ultrafiltrates of serum, peptone, yeast-extract, protein hydrolysates,
etc. These supplements make up for deficiencies in the synthetic media
which are usually quantitatively, and probably also qualitatively,
minor. The fact that a number of cell types has been maintained in
completely defined media for hundreds of serial passages, and can
presumably be so maintained indefinitely, supports the hope that, for
other cells which have not yet been maintained in this way, the necessary alterations to current media to make them suitable for these will
be small, in some cases possibly only quantitative (changes in the proportions of present constituents) rather than qualitative (introduction
or omission of components). Serum is still the principal supplement
used to correct the deficiences and add to the effectiveness of chemically
defined media. The question of the role and function of these supplements is still very much an open one. Some, but not all, contain
proteins. Peptones and protein hydrolysates are exceptions, but there
is still a widespread belief that the proteins themselves are nutritionally
important. Lucy (1960) has concluded, from a survey of the evidence,
that dependence upon protein for growth may range all the way from
"cells which can multiply in the absence of protein" to "others which
cannot even survive". What remains to be determined is whether
the cells which, at present, cannot even survive without protein, may
eventually be able to do so when suitable small molecules, either
associated with the protein, or part of its structure, are substituted for
the protein itself. In addition to the implication of proteins in the
highly important aspects of total environment relating to attachment
of cells to surfaces and to a possible strictly nutritional role, a very
probable function is that of carrier of minor nutrients of low molecular
weight (Vann, 1956; Chang, Pennell, Keller, Wheaton and Liepins,
1959; Gwatkin, 1960).
E*
105
found to promote adhesion of HeLa, clone S3-Y, cells. Certain formulations of glass were better than others, and treatment with N a O H
improved the adhesive qualities of some of the less satisfactory glass
surfaces. Strain-L mouse connective-tissue cells differ from the HeLa
strain of human cervical carcinoma in excreting protons at a lower
rate, and can attach to surfaces of lower total negative charge. These
aspects of the total environment are highly important for the success
or failure of cultivation of cells in defined media. In stationary cultures,
adhesion of cells to glass is often, though not always, a prerequisite for
subsequent cell division. In suspension, "protective" macromolecules
appear to play a role (cf. Swim and Parker, 1960; Bryant, Schilling,
Earle and Evans, 1960; Bryant, Evans, Schilling and Earle, 1961).
It is still today a widespread practice to supplement synthetic media
with small amounts (20°/o and downwards) of serum, dialysates or
ultrafiltrates of serum, peptone, yeast-extract, protein hydrolysates,
etc. These supplements make up for deficiencies in the synthetic media
which are usually quantitatively, and probably also qualitatively,
minor. The fact that a number of cell types has been maintained in
completely defined media for hundreds of serial passages, and can
presumably be so maintained indefinitely, supports the hope that, for
other cells which have not yet been maintained in this way, the necessary alterations to current media to make them suitable for these will
be small, in some cases possibly only quantitative (changes in the proportions of present constituents) rather than qualitative (introduction
or omission of components). Serum is still the principal supplement
used to correct the deficiences and add to the effectiveness of chemically
defined media. The question of the role and function of these supplements is still very much an open one. Some, but not all, contain
proteins. Peptones and protein hydrolysates are exceptions, but there
is still a widespread belief that the proteins themselves are nutritionally
important. Lucy (1960) has concluded, from a survey of the evidence,
that dependence upon protein for growth may range all the way from
"cells which can multiply in the absence of protein" to "others which
cannot even survive". What remains to be determined is whether
the cells which, at present, cannot even survive without protein, may
eventually be able to do so when suitable small molecules, either
associated with the protein, or part of its structure, are substituted for
the protein itself. In addition to the implication of proteins in the
highly important aspects of total environment relating to attachment
of cells to surfaces and to a possible strictly nutritional role, a very
probable function is that of carrier of minor nutrients of low molecular
weight (Vann, 1956; Chang, Pennell, Keller, Wheaton and Liepins,
1959; Gwatkin, 1960).
E*