Stem Cell Technology
When you think of the latest news and developments in the field of Bio Technology,
the thing that comes straight to mind is STEM CELL TECHNOLOGY.
So what are stem cells and what is all the hype about??
What would you say if I told you that I could grow any part of the human body from a small number of little cells. See now we are getting excited, aren’t we? That is exactly what scientists believe that stem cells have the potential to do.
What are stem cells?
Stem cells are a type of primitive cell. Scientists have found ways of developing
these stem cells into most types of human cells (the human body contains 220
different types of cells). Researchers have achieved success in converting stem
cells into the type of cells found in blood, brain, heart tissue, nerves, bones,
etc. and research is still being carried out extensively. Researchers are confident
that they will lead to treatments to many diseases: bone loss, broken bones,
brain damage due to oxygen starvation, severe burns, cancer (some forms), diabetes,
heart disease, hepatitis, incomplete bladder control, leukemia, lupus, muscular
dystrophy, multiple sclerosis, osteoarthritis, Parkinson's,etc. The list just
goes on and on.
Stem Cells were first harvested in the lab in 1998, when researchers at the
University of Wisconsin and the Johns Hopkins University found a way of harvesting
stem cells and maintaining their growth in the lab.
Origin of stem cells
Stem cells are currently being harvested from 3 sources:
a. Pluripotent stem cells found in unwanted embryos
b. Hematopoietic stem cells found in bone marrow
c. Neural stem cells in nervous tissues.
These cells are commonly extracted from unwanted embryos. These are typically surplus embryos that are created during medical procedures, which help infertile couples conceive. When a woman undergoes in-vitro fertilization, she is given medication that causes her to produce perhaps two-dozen mature ova. These are then fertilized, usually with sperm provided by her husband. After fertilization, two to four embryos are implanted in the woman's womb, in the hope that one or two will develop into a single newborn or twins. The rest are quickly deep frozen in liquid nitrogen for potential future use.
These embryos have no brain, central nervous system, mouth, heart, lungs, or other internal organs. They have no organs of any kind. They simply contain a number of identical, undifferentiated cells containing human DNA. It should be noted however that they do have the potential to grow into fetuses and become newborn babies.
The properties and potential of stem cells:
Stem cells share two characteristic properties:
(1) unlimited or prolonged self-renewal (that is, the capacity to maintain a
pool of stem cells like themselves), and
(2) potency for differentiation, the potential to produce more differentiated
cell types—usually more than one and, in some cases, many.
The most useful stem cells are found in embryos. In an embryo, cells form an outer layer which later become the placenta. But cells located in the inner layer have not determined what they will eventually be. These 'pluripotent' cells could become many of the 220 types of cells in the human body.
Stem cells from bone marrow and nervous tissues are limited in potential as
compared to embryonic stem cells. Cells removed from embryos have two extremely
valuable properties:
1.They can divide for long periods of time in the lab to produce more stem cells.
2. They can transform themselves into any of the cells present in the human
body.
Some of the potential uses of stem cells may be:
Methods may be found whereby they could be formed into replacement tissue and
even entire organs. They may eventually be used to repair injured or poorly
functioning brains and nervous systems. New, more effective treatments may be
developed for a wide range of injuries, disorders and diseases.
To date, preliminary research looks very encouraging:
(1). James Thompson at the University of Wisconsin was able to make stem cells
grow into human heart cells. (In order to avoid violating a congressional ban,
he took extreme precautions to do his research in a room in which not a single
piece of equipment -- not even an electrical extension cord -- had been purchased
with federal funds.)
(2). John Gearhart of Johns Hopkins University has been able to grow nerve cells
from stem cells.
(3). Researchers have been able to implant heart muscle cells grown from stem
cells into the hearts of mice and observe them "successfully repopulate
the heart tissue and integrate with the host cells."
(4). Researchers have coaxed stem cells to develop into a urinary sphincter
muscle for a pig. This has the potential to help people regain bladder control
-- a common problem that limits mobility and the quality of life of the elderly.
(5). Dr. McKay and colleagues of the National Institute of Neurological Disorders
and Stroke (NINDS) were able to take a special type of stem cell from rat embryos
and successfully treat a Parkinson's-like disease in rats. They used neural
stem cells that can only develop into nervous system cells. Most of the test
rats showed "about a 75% improvement in motor function 80 days after they
received the transplants."
Future Potential Applications
If researchers can decode how the differentiation process works then
causes and cures for various birth defects and even cancer might be discovered.
Researchers might be able to develop specific cell types, tissues, organs, etc. from stem cells, which could then be used to study the effects of new drugs. This should reduce the number of animal studies and human clinical trials that are required before new drugs are approved.
The Stem Cell Technology and research shows a great potential for development
of cures for diseases that have troubled mankind since long and it really is
a great hope for the future and a field in which a lot of work is still to be
done.
April 2006, Jeev
http://www.dce.edu/jeev
This work is licensed under a Creative Commons Attribution 2.5 License.