C/7. 6— Alternatives to Animal Use in Research • 119 
Table 6-2.— Properties of In Vitro Culture Systems 
Preparation and 
consequences 
Level of tissue 
organization 
Reproducibility 
Expression 
similar to 
in vivo 
Genetic alteration 
by mutation 
and/or selection 
Environmental 
control 
Intact system (no consequence) .... 
Organ culture (remove influences of 
+ + + + 
+ + + + 
+ + + + 
+ 
+ 
whole organism) 
Tissue culture (remove influences of 
+ + + + 
+ + + + 
+ 4o + + + 
-1- 
+ + 
whole organisms) 
Primary cell cultures (disrupt 
+ + + 
+ + + 
+ to + + + 
+ 
+ + + 
intercellular relationships) 
Cell lines (intercellular relationships 
are reduced; cell proliferation is 
enhanced, at times with little 
0 
+ + 
+ to + + + 
+ 
+ + + + 
control) 
0 
+ + + + 
+ to + + + 
+ to + + + + 
+ + + + 
KEY: + + + + = High degree; + + + = Moderate degree; + + = Modest degree; + = Some degree; 0 = None. 
SOURCE: Adapted from R.M. Nardone and L.A. Ouellette, “Scope of ‘Alternatives’: Overview of the State of the Art,” contract report prepared for the Office of Technology 
Assessment, U.S. Congress, July 1984. 
tissues, and cells in the body. Nevertheless, im- 
proved accessibility of added chemicals and the 
opportunity to achieve genetic homogeneity by 
cloning and genetic manipulation by selection and 
fusion are important trade-offs. Indeed, at times 
cell-to-cell interaction may interfere with an ex- 
perimental objective (156). 
The explosive growth of in vitro research dur- 
ing the 1960s and 1970s is illustrated by the fact 
that the Index of Tissue Culture had 84 pages of 
entries in 1965, 207 pages in 1970, 566 pages in 
1975, and 636 pages in 1980, when the publica- 
tion was discontinued because computerized in- 
formation retrieval was warranted. There is vir- 
tually no field of biomedical research that has not 
been affected by in vitro technology . In vitro mod- 
els for the study of cell senescence, atherosclero- 
sis, development, growth, and immune reactions 
are illustrative of the diversity of applications in 
biomedical research (156). 
The specific conditions that best support the 
maintenance, growth, or differentiation of each 
type of culture must be determined before any 
useful information can be garnered. Some of the 
general requirements of culture systems are com- 
binations of the proper gas atmosphere, humid- 
ity, temperature, pH, and nutrients . Other culture 
systems may also have specific light, motion, pres- 
sure, and physical or chemical support require- 
ments. Under the proper conditions, many can be 
subcultured for months or frozen in liquid nitro- 
gen for years without loss of their unique, differen- 
tiated properties. 
The ability to maintain many continuous cell lines 
has opened the floodgates of experimentation and 
made the new technologies accessible to all the 
disciplines of biomedical research. Other advan- 
tages include ease of transport from one labora- 
tory or country to another, the ability to culture 
both normal and abnormal tissue for comparison 
and research, the use of human cells to eliminate 
species variation, and the ability to expose cultures 
directly to exogenous molecules at specific concen- 
trations for precise time periods. Disadvantages 
include the changes in structure or function ob- 
served in some cultures , and the fact that isolated 
systems give isolated results that may bear little 
relation to results obtained from the integrated 
systems of whole animals. 
Organ Culture 
At some point in the history of research, inves- 
tigators have attempted with varying success to 
isolate and maintain every major and minor mam- 
malian organ, for a variety of purposes. In recent 
years, improved techniques, such as the availabil- 
ity of artificial blood media, have increased the 
probability of successful organ culture. Blood, or 
artificial blood media, can be pumped through the 
organ to sustain it (“perfusion”) (see fig. 6-2). Cur- 
rent applications of organ perfusion include the 
study of protein synthesis in lactating guinea pig 
mammary tissue (136) and the use of human pla- 
centas in toxicology studies, with additional po- 
tential for use in oncology and gerontology re- 
search (99). 
