Cell Therapy: What Is It?
Cell therapy involves the use of human blood transfusions and bone marrow transplants as
well as injections of cellular materials. Cell therapy refers to the injection of cellular material from
organs, fetuses, or embryos of animals to stimulate curing and
treat a variety of degenerative diseases.
Several schools of thought exist as to the ideal
practice of cell therapy. The various methods include the use of
live cells, freeze-dried cells (including whole cells and cell
extracts), cells from specific organs, and whole embryo
preparations. All of these techniques have been used successfully,
with different methods targeting different conditions.
Ted Allen, cell therapy expert, M.D.,
of Nassau, the Bahamas, says that initially live cells from organs of
freshly killed sheep were used, but the time from the extraction of
organs and cells to their subsequent injection was too short to
allow for adequate sterility testing. With live cells there is also
the possibility of an immune
reaction rejecting the transplant, as often happens
with organ transplants.
In 1949, Swiss scientists at Nestl
developed
the freeze-drying method of processing coffee. Professor Niehans
worked with the Nestl company
to adapt this technique to conserve biological matter without damage.
The result was a process in which sterility could be regulated and
cell material could be conserved for longer periods of time. In this
method, the injected cellular material contains a lesser amount of
foreign protein
than when an entire organ is transplanted, substantially reducing
the rejection risk.
When whole cells are used in this freeze-drying
procedure, the cell surface is still present. This surface is
antigenic, meaning it may cause an immune response. For this reason,
patients who receive freeze-dried whole cells should be warned of
the possibility of an allergic reaction, although the likelihood of
this occurring is rare.
The process of ultrafiltration (the fine
filtering of homogenized whole cells down to cell components called
ultrafiltrates) removes the cell surface coat and its antigenic
material (a protein or carbohydrate
substance, such as a toxin or enzyme)
in order to reduce the risk of rejection. The use of freeze-dried
cell ultrafiltrates also allows for better quality control and
prolonged storage.
Another important aspect of cell therapy is the
use of cells taken from embryos. Animal embryo cells do not induce immune sensitization or rejection because they do
not yet bear the surface antigens.
Today most cell therapy employs embryonic
tissues. However, in cases involving the parathyroid, adrenal,
pituitary and sex glands, adult tissues are used, as these glands
are too underdeveloped in the embryos. According to Dr. Allen,
mature sheep have proven to be the best donor animals of organ cells
as their proteins rarely trigger an allergic reaction in the
recipient. More recently, cells from pigs have been found to work as
efficiently, according to Peter Stephan, M.D., of the Stephan Clinic
in London, England.
Human Fetal Cell Transplants
In 1988, former President Reagan placed a ban
on any new research involving human fetal tissue. In 1993, President
Clinton lifted the ban, enabling scientists to resume work in this
field. A study published in the New England Journal of Medicine
in 1992 reported that the transplantation of human fetal cells has
been successfully used to treat patients with Parkinson's disease.
In the case of Parkinson's, cells that normally produce the
neurotransmitter dopamine
die off, resulting in a loss of muscle control. When fetal cells
from a corresponding area of the brain are injected into the brain
of a Parkinson's patient, many of the symptoms, such as tremors and
paralysis, have been known to disappear. The studies cited marked constant improvement in
the patients' motor skills and reported diminished symptoms and
signs of Parkinson's as a result of these transplants.
Fetal cell transplants are also being
investigated as a possible therapy for Alzheimer's disease, a chronic
mental disorder involving progressive, irreversible loss of
intellectual functions including comprehension, memory, and speech.
Because fetal tissue is especially adaptive to transplantation,
scientists are hopeful that transplanted fetal cells will be able to
assume the functions of cells that have been destroyed or damaged.
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