Cloning and Stem Cell Research (Recent Breakthroughs in South Korea)
(Dr. Mohammad Abul
Farah, Seoul, South Korea)
In biology, a clone is
a cell or an organism that is genetically identical
to another cell or organism. Many simple organisms such
as bacteria reproduce themselves by copying their DNA
and splitting in half. The two bacteria that result
from this form of asexual reproduction are genetically
identical; they are clones of each other. In contrast,
during the process of sexual reproduction, the nucleus
of a sperm cell, which carries the father's DNA, fuses
with the nucleus of the egg cell, which contains the
mother's DNA. The resulting offspring carry genetic
material from both parents and are not identical to
either parent. Usually, when scientists clone an animal,
they take the nucleus of a cell, which contains chromosomes
made of deoxyribonucleic acid (DNA) and proteins and
place it into an egg cell (also called an oocyte) from
which the nucleus has been removed. The egg cell then
divides to produce an embryo that develops into an animal.
Three different types of cloning technologies are used
(1) recombinant DNA technology or DNA cloning, (2) reproductive
cloning, and (3) therapeutic cloning. The terms "recombinant
DNA technology," "DNA cloning," "molecular
cloning," or "gene cloning" all refer
to the same process: the transfer of a DNA fragment
of interest from one organism to a self-replicating
genetic element such as a bacterial plasmid. The DNA
of interest can then be propagated in a foreign host
cell. Reproductive cloning is a technology used to generate
an animal that has the same nuclear DNA as another currently
or previously existing animal. In a process called "somatic
cell nuclear transfer" (SCNT), scientists transfer
genetic material from the nucleus of a donor adult cell
to an egg whose nucleus, and thus its genetic material,
has been removed. Once the cloned embryo reaches a suitable
stage of cell division, it is transferred to the uterus
of a female host where it continues to develop until
birth. Therapeutic cloning, also called "embryo
cloning," is the production of human embryos for
use in research. The goal of this process is not to
create cloned human beings, but rather to harvest stem
cells that can be used to study human development and
to treat disease. Stem cells are important to biomedical
researchers because they can be used to generate virtually
any type of specialized cell in the human body.
A stem cell is a cell that has the ability to divide
(self replicate) for indefinite periods-often throughout
the life of the organism. Stem cells have two important
characteristics that distinguish them from other types
of cells. First, they are unspecialized cells that renew
themselves for long periods through cell division. The
second is that under certain physiologic or experimental
conditions, they can be induced to become cells with
special functions such as the beating cells of the heart
muscle or the insulin-producing cells of the pancreas.
Embryonic stem cells, which have been cultured under
in vitro conditions that allow proliferation without
differentiation for months to years. Scientists primarily
work with two kinds of stem cells from animals and humans:
embryonic stem cells and adult stem cells, which have
different functions and characteristics that can be
used for stem cell therapy.
Recently, Professor Hwang Woo-suk and his colleagues
in the Seoul National University, South Korea, made
two stunning scientific landmark with his successful
cloning of dogs and making patient specific stem cells.
Professor Hwang is a stem cell pioneer and also known
as ‘king of cloning’, who successfully cloned
human embryo last year. First, they have established
11 human embryonic stem cell lines by somatic cell nuclear
transfer of skin cells from patient with disease or
injury into donated oocytes. The resultant cells were
a perfect match for the individuals and could mean for
the treatment of disease like diabetes and Alzheimer’s
without problem of rejection. Each of the newly created
stem cell lines is genetically identical to one of Hwang’s
patients so any new tissue derived from that patient’s
cell line can be injected into that individual without
causing an immune reaction. The customized stem cells
opened the door to therapeutic cloning, which has been
touted as a futuristic remedy for hard-to-cure diseases.
Next, they revealed World’s first
cloned dog, SNUPPY (a combination of Seoul National
University and Puppy) a male Afghan Hound
that was born in April 2005. Snuppy is the latest mammal
to be cloned after sheep, mice, cats, rats, cows, goats,
pigs, horses, rabbits and a mule. To create the world’s
first dog clone, Hwang’s team used somatic cell
nuclear transfer, merging somatic cells with enucleated
eggs to produce clones. DNA analysis of the puppies
revealed them to be genetically identical to the donor
dog, the Afghan Hound Tai. Successful nuclear transfer
in dogs has been elusive until now because it is difficult
to get egg cells to mature in the lab. Dog eggs have
been problematic because they are released from the
ovary at an earlier, less mature stage than in other
mammal. Therefore, the technique is still very inefficient
because as many as 1,095 eggs and 123 surrogate dogs
were used to create just three pregnancies. One of the
three was miscarried and among the two cloned baby Afghan
Hounds who saw the light, one died of pneumonia a mere
22 days after its birth.
Scottish embryologist Scot Wilmut banked on the method
to make the first cloned mammal, Dolly the Sheep, in
1997. They were trying to find ways to produce livestock
that carry specific genetic traits by creating Dolly.
With the success of dog cloning, Korean scientists proved
that they retain the best technologies and know-how
as far as animal cloning is concerned. Dog cloning research
is of great value because cloned dogs can be used as
a model to study the pathogenesis and treatment of human
diseases since dogs and humans share many physiological
characteristics.
The cloning technology generally provides the benefits
of preserving rare species and therapeutic cloning.
Once dog embryonic stem cells become available, this
technology could become a useful research tool for studying
the genetics of outcrossed population. Studying stem
cells will help us understand how they transform into
the dazzling array of specialized cells that make us
what we are. Some of the most serious medical conditions,
such as cancer and birth defects, are due to problems
that occur somewhere in this process. A better understanding
of normal cell development will allow us to understand
and perhaps correct the errors that cause these medical
conditions. Another potential application of stem cells
is making cells and tissues for medical therapies. Today,
donated organs and tissues are often used to replace
those that are diseased or destroyed. Stem cells offer
the possibility of a renewable source of replacement
cells and tissues to treat a myriad of diseases, conditions,
and disabilities including Parkinson's and Alzheimer's
diseases, spinal cord injury, stroke, burns, heart disease,
diabetes, osteoarthritis and rheumatoid arthritis.
Hailing these breakthroughs, it would be expected that
the medical feat opens the door to gene therapy, as
transplanting developed stem cells back into patients
with degenerative diseases such as Alzheimer’s,
Parkinson’s and diabetes may be possible.
Contributed by:
Mohammad Abul Farah, Ph.D.
He attended Aligarh Muslim University in India where
he received his M.Sc. and Ph.D. in Zoology with specialization
in Genetics. He also served as Senior Research Fellow
of Council of Scientific and Industrial Research, India.
At present, he is working as a Research Scientist in
Proteonik Inc., a biotechnology venture company based
in Seoul, South Korea, on Diabetes research focusing
on insulin signaling pathway.
NOTE
This article was contributed in October 2005, later
those landmark papers were found to be exposed as a
fabrication, and become one of the biggest scientific
frauds of recent history. The Seoul National University
Investigation Committee, initially organized to investigate
the claims of scientific misconducts by professor Woo
Suk Hwang and co-workers reports that Professor Hwang's
research team possesses neither the patient-specific
embryonic stem (ES) cell line described in 2005 publication
nor the NT-1 ES cell line, the forerunner cloned cell
line described in
2004 publication. The data in 2004 publication are
also fabricated as can be seen by the non-match between
the donor A and NT-1. Such act is none other than deceiving
the scientific community and the public at large. The
investigation's findings have stunned the scientific
world and South Koreans, in particular. However, the
panel said that the creation of first cloned dog, Snuppy
was genuine.
Timeline of scandal:
Feb 2004 Hwang Woo-suk's team
declares they have created 30 cloned human embryos and
harvested stem cells from one of them.
May 2005 Team says it has made
11 pateint specific stem cell lines from skin cells.
Aug 2005 Hwang and colleagues
announces in Nature that they have cloned the first
dog, an Afghan Hound, called SNUppy.
Nov 2005 Hwang apologises for
using eggs from his own researchers
Dec 15 A colleague claims stem
cell research was faked
Dec 23 Academic panel finds
results were 'intentionally fabricated'
Dec 29 Panel finds no data to
back study
To read full report of investigation committee on Dr.
Hwang stem cell research scandal please visit: http://www.snu.ac.kr/engsnu/
