cells at the injury site into primitive, possibly totipotent cells; a profound alteration in both function and
morphology. This may require some explanation.
In normal embryogenesis, the original fertilized egg cell contains all of the genetic programs
(genomes) for the total adult organism, including all of the various cell types, each expressed as a
separate genome. As the organism grows, these various specialized cells appear when the genomes for
all of the other cell types are repressed. Thus the nucleus of a muscle cell for example has the genome
for muscle unrepressed and operating and the genomes for all of the other cell types present but
repressed. The genome produces the specialized cell type by governing the production of specific
proteins which make up the cell itself. Dedifferentiation consists of derepressing these repressed
genomes so the cell returns to a more primitive, less differentiated level and now has the option to
redifferentiate into a new cell type, depending upon its local circumstances.
In the previous sections of this chapter experiments were described in which low levels of DC
were administered to groups of cells within the organism with growth responses as predicted by theory.
This type of phenomenological experiment is useful to define the functions of the DC l system and the
general cellular responses, but it tells us nothing about the cellular-level mechanisms involved. At this
time there are unfortunately few studies reported in the literature at this level. This is due in part to the
enormous complexities of the living cell and our lack of knowledge in this area. Also, since the total
organism is a complex of interrelating systems of biochemical and biophysical factors, one cannot
assume with any degree of confidence that a cellular change following the application of DC energy to
the intact organism is due primarily to the electrical current or to some second-order effect.
The only viable experiments, therefore, are those carried out on isolated cell populations where
the only factor changed is the electrical current. If the electrical factors are within the levels observed in
the living organism, the cellular changes observed may be inferred to be the same as those occurring
within the organism in response to the normal operation of the DC system. Even here, however, an
unavoidable artifact is introduced by the presence of the metallic electrode. The passage of current,
even at low levels, through such an electrode produces electrochemical alterations that are not present
in the living system. Another artifact is produced by the tendency of almost all normal cells in culture
to change their morphology and function (the culture circumstance is presumably "sensed" by the cells
as being different from that of their normal position within the organism). Therefore such in vitro
experiments must utilize normal cells in culture before such changes even begin. These constraints
require a normal cell type that can easily be harvested from the normal animal, that can be paced
immediately within a culture system approximating the normal internal milieu, that demonstrates a
definite alteration in a short time after exposure to currents simulating those found in the living animal.
Therefore all standard-type tissue and cell culture experimental situations are theoretically not capable
of producing unequivocal results.
In the course of studying the electrical factors associated with fracture healing, a regenerative-
type growth process in the frog, such an ideal cell system was inadvertently discovered by our group in
1967 (47). We found that the red blood cells in the blood clot that formed between the fracture ends
underwent a dedifferentiation process, transforming into the fracture blastema and eventually becoming
bone. It should be noted that the red blood cells of all vertebrates, other than mammals, are complete
cells, retaining their nuclei in the adult circulating state. This nucleus is, however, quite inactive; the
cytoplasm contains relatively few subcellular organelles and in general the total cell is in a quiescent
state. The cytoplasm of course contains a large amount of hemoglobin, and the cell is considered,
despite the presence of the nucleus, as analogous to the mammalian red cell, which is non-nucleate and
totally inactive. Therefore the dedifferentiation process, while being all the more remarkable in view of
ELECTROMAGNETISM & LIFE - 37