National Spinal Cord Injury Association Resource Center
Factsheet #6:
The Importance of Basic Science in Spinal
Cord Injury Research
Introduction
The ultimate dream for many people with a spinal cord
injury (SCI) - or for those who care about someone with
SCI - is that a cure will be found as quickly as
possible. Every few months a newspaper, magazine, or
television show seems to re-port a new
"breakthrough" for people with SCI, yet those
optimistic reports never seem to be followed by stories
of people "cured" of SCI. If these scientific
"breakthroughs" are occurring, then why is SCI
still incurable? Why don't these
"breakthroughs" lead to actual improvements in
the conditions of those whom we know have a SCI?
The purpose of this information sheet is to analyze
why scientific findings often called
"breakthroughs" are of importance to people
with SCI and to understand how the term
"breakthrough" can be mis-used. Although an
important finding at the basic science level will not
lead to an immediate remedy for SCI, progress in basic
science is essential to the ultimate goal of finding a
cure for SCI.
Spinal Cord Injury - The
Problem
When spinal cord damage occurs, its most obvious
effect is a loss of sensation or movement below the level
of injury. Useful func-tion is eliminated below the site
of neural damage. For some rea-son, the body is unable to
restore this path of communication, so the consequences
are permanent. In contrast, a broken leg will cause some
temporary disability, but eventually the bone will mend.
Even with other serious injuries, such as burns, new skin
may re-grow, although it often is badly scarred.
The peripheral nervous system (PNS) includes all of
the nerves in the body except for the brain, spinal cord,
eye, and optic nerve and is able to heal itself after an
injury. For example, if you have a bad cut on your finger
you may temporarily lose some sensation if a nerve has
been damaged. However, nerve endings in your finger
eventually will grow back and re-establish their
appropriate connections, as is the case with nerves in
the PNS.
With a SCI though, or damage to other central nervous
system (CNS) cells, the loss of function is usually
permanent. This has two fundamental causes. When there is
a traumatic injury leading to the death of nerve cells,
the CNS is unable to grow new cells to replace the
damaged ones. Even more important, however, many of the
nerve cells that are injured, but not killed, are
effectively unable to grow new sprouts that reconnect
with other injured (or uninjured) nerve cells on the
other side of the damaged zone. Without such a precise
form of reconnection, as can occur following PNS
injuries, the loss of function becomes permanent.
Clearly, the long term clinical goal of research in
SCI is to develop a means of assisting the nerves in the
spinal cord to heal, or regenerate. Before this objective
can be accomplished, however, there are some fundamental
problems to overcome. The most import-ant dilemma is our
ignorance of biological processes normally in control of
the growth and regeneration of the nervous system. In
fact, biologists still know rather little about the
crucial regula-tory systems that allow a single
fertilized egg cell to grow into an elaborate animal.
To attempt to find a "cure" for SCI before
understanding these basic facts is like trying to bake a
cake without knowing the in-gredients, the correct
amounts of those ingredients, or the tem-per-ature at
which they would need to be baked in order to come out
with a successful finished product. It is, of course,
possible to conduct trial and error experiments with cake
ingredients and even-t-ually develop a reasonable
facsimile of a cake. However, the spinal cord is many
times more complex that this proverbial cake! Moreover,
it is not yet known for sure the "ingredients"
required, much less the relationship of those ingredients
to each other and the cellular environment in which they
operate, making trial and error approaches to a cure for
SCI unreasonable.
The only way an appropriate "recipe" for
spinal cord regeneration can be developed, therefore, is
to find the answers to the basic questions about cell
formation, interactions between cells and cell death.
Once scientists have a fairly good idea about the answers
to those questions, it will be possible to begin in
earnest the task of finding a way to change the CNS's
response to injury to allow for regrowth - or
regeneration - of the spinal cord.
Basic Science - Important
Questions for Spinal Cord Regeneration
The CNS is composed of the brain, spinal cord, eye and
optic nerve. While it was once thought that CNS cells
cannot regenerate, it has recently been shown that they
can, but do not do so effectively in mammals. In order to
understand why nerves do not grow properly under some
conditions, it is first important to determine what
actually happens when they grow. One important way to
look at regeneration, therefore, is to carefully examine
the processes of nerve growth and regeneration wherever
they are most accessible to our current techniques.
Consequently, many scientists study nerve cells in
animals that one would not expect to have particular
rele-vance to the human spinal cord - such as goldfish,
frogs, or even the sea snail, Aplysia.
Despite the obvious differences between species within
the animal world, experiments conducted in
"simple" animals compared to the more complex
animals can provide important answers to basic
biolog-ical questions that will be helpful to answering
human centered issues as well as questions about those
specific species. These simple animal models provide
relatively neat and uncluttered envir-on-ments in which
to study specific questions. The less complicated a
theory is, and the fewer complicating variables there are
when studying it, the more likely one is to be able to
come up with a definitive result.
The human spinal cord is an incredibly complex organ.
Proper spinal cord function is dependent upon an
intricate interaction among individual cells, each of
which has a specific function and a unique role in the
CNS. The best way to study the unique roles of cells and
their interactions with other cells is to develop simple
animal models that enable one to isolate a particular
cell-ular relationship rather than to try to sort out a
multitude of relationships at the same time. Once those
basic relationships are clearly understood, it will be
possible to examine with some degree of understanding the
complex environment of several differ-ent processes
occurring at the same time.
At the present time, scientists still do not
understand clearly how a human spinal cord functions
under normal conditions. Thus, one of the most pressing
concerns today is to develop definitive answers to
questions concerning basic CNS function. A second
im-port-ant area to examine is that of cellular response
to injury. How does the CNS respond to injury? Again, a
good way to address this questions is to look at animal
systems that do regenerate CNS cells. If scientists can
determine how other animals accomplish what we would like
to see in humans, then they can begin applying that
knowledge to finding a cure for SCI.
It is important to realize that the goal of basic
science research is to answer basic questions about
biology. Once the answers to the most basic biological
questions are found, then it will be neces-sary to
determine how the various systems work together in
animals and in humans. Much further down that road of
course is the development of experimental treatment
approaches to reverse the effects of SCI.
Evaluating
"Breakthroughs"
Every once in awhile, a newspaper or magazine article
will announce that a particular scientist recently
reported findings at a meeting or in a scientific journal
that represents a potential "breakthrough" for
people with SCI. The implication of the article often is
that the results announced by this scientist will make
paralysis due to SCI a thing of the past, or at the very
least, will speed up the process of finding a cure. How
is one to interpret these kinds of reports?
One important factor to keep under consideration is
that the process of scientific investigations is a long
and complicated one, with many basic questions still
unanswered. A "breakthrough" re-gard-ing even
one of the most basic biological questions discussed
earlier certainly may represent an important step forward
in one particular area of understanding, but many equally
important funda-mental questions about cell function
still remain unanswered. The "breakthrough" in
and of itself, therefore, is unlikely to lead to any
significant advance in our understanding of the
mechanisms that occur as a result of SCI, and certainly
will not lead directly to a "cure."
A second factor to keep in mind is that science is not
as definitive a discipline as most lay people would like
to think. Even though one scientist may propose a
particular theory about how the CNS works, and may indeed
provide evidence to support that theory, it is extremely
difficult to prove without a doubt that one's theory is
completely correct. In fact, unproven theories may be
presented, other scientists may agree with the
interpretation of the data, yet eventually the theory
will be proven to be completely incorrect.
In the medical field, for example, the practice of
"bleeding" a patient was once used widely by
physicians. Because the common belief was that
"bleeding" was beneficial, doctors continued
with the practice and interpreted the "data" to
support the theory that "bleeding" was a good
treatment. In other words, the eventual survival of some
patients was attributed to good care, including
"bleeding," while death was attributed to other
factors.
In science, the same kind of thing can happen, but
because of the lack of knowledge most of us have about
basic science principles, and because of our intense
desire to have answers that will lead to clinical
advances, we are less aware and less willing to accept
the lack of "hard data" to support various
theories. Consequently, it is important to realize that a
reported "breakthrough" may or may not
represent an important step forward, and that time will
be the best judge of its value.
Summary
A cure for SCI is clearly needed, and for those who
have an injury or know someone with SCI, the amount of
time it is taking to develop a cure seems unacceptable.
It is easy to see why we want to accept claims of
"breakthroughs," and why we are willing to
believe promises by scientists or others that a
"cure" will be found in five years, or ten
years, or some other specified time period. With the
amount of knowledge currently available about spinal cord
function and dysfunction, however, it is impossible to
predict when or even if a cure will be found.
As much as we would like to see an immediate cure for
SCI, "shortcut solutions" are unlikely to
produce one. The key to finding an eventual cure is in
supporting basic research efforts slowly developing the
answers to the most fundamental questions in biology.
Only when those questions are answered will it be
pos-sible to develop approaches toward curing SCI and
other unaccept-able medical conditions.
NSCIA 8/95
The National Spinal Cord Injury
Association would like to thank Lynn Phillips-Bryant for
contributing her time and expertise in the preparation of
this Factsheet. This Factsheet is offered as an
information service and is not intended be a
comprehensive overview of work in the field. Any
information you may have to offer to further update this
Factsheet would be greatly appreciated. The National
Spinal Cord Injury Association Resource Center (NSCIRC)
provides information and referral on any subject related
to spinal cord injury. Contact the resource center at
1-800-962-9629.
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