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In the name of God
Stem Cells
Questions & Answers
•
http://www.webmd.com/a-to-z-guides/features/stem-cells-faq-9-questions-answers
1- What are stem cells?
• Stem cells are unspecialized cells that can
become other types of cells.
2-What's the difference between adult stem
cells and stem cells taken from an embryo?
• Embryonic stem cells are stem cells in an
embryo. They can develop into a wide range
of cell types.
• Scientists have found that a few stem cells
persist even after birth; those are adult stem
cells. Most adult stem cells can form a limited
number of cell types.
Stem Cell Cultivation
University of Wisconsin-Madison
3- What's the controversy about?
• There's no controversy about adult stem cells.
But when it comes to embryonic stem cells,
some people argue that an embryo is a living
human being and destroying an embryo for any
reason is morally unacceptable. Other people
say that embryonic stem cells have the potential
to cure many diseases, and that the embryos
used would have been discarded by fertility
clinics anyway.
4- Why not just study adult stem
cells?
• Adult stem cells have some advantages. When they come
from your own body, your immune system will probably not
try to reject them. And adult stem cells aren't controversial.
But there are three main disadvantages to using adult stem
cells:
• Adult stem cells aren't able to form all types of cells, so their
use may be limited.
• Adult stem cells are rare among the body's billions of cells,
so they're hard to find.
5-Where do scientists get the embryos
they use?
• From in vitro fertilization (IVF) clinics.
• Many women who have difficulty having a baby use IVF.
Doctors collect eggs from the mother and sperm from the
father, and put them together in the laboratory. The doctors
implant one or more of the resulting embryos in the mother.
Other embryos are frozen and stored, in case the first
embryo implanted doesn't take. But all of those frozen
embryos may not be used. According to federal policy,
embryonic stem cells used for research can only come from
embryos created for reproductive purposes that are no
longer needed and the donors must consent and not profit
financially from the donation.
6- Could there be alternatives to studying
embryonic stem cells?
• Maybe. In 2007, scientists in the U.S. and Japan
reported successfully reprogramming human skin
cells to act like embryonic stem cells.
• There is a catch. To reprogram the skin cells, the
researchers had to use retroviruses as vectors to
carry new genes into the cell nucleus. Once there,
the retroviruses become part of the cell's genetic
code. These retroviruses could cause deadly
mutations or cancers in patients treated with the
newly created stem cells.
7-Have any diseases been cured with embryonic stem
cells in people?
• A. No. But in January 2009, Geron Corp. got
approval to test embryonic stem cells in 10 patients
paralyzed by spinal cord injury.
• In November 2008, doctors in Europe performed
the first trachea trcellsansplant that used the
patient's own adult stem; no embryonic stem cells
were used.
8- Which diseases could be treated with
stem cells?
• Researchers are studying stem cells for conditions
including:
– Diabetes:
• Stem cells could help make insulin-producing cells for diabetes
patients.
– Parkinson's disease:
• Stem cells may be able to make new nerve cells in the brain to
replace those destroyed by Parkinson's disease.
8- Which diseases could be treated with
stem cells? ….
– Cancer:
• Stem cells might help recreate bone marrow, make cells that
could kill the cancer, and replace cancer-damaged tissue.
– Spinal cord injury: Stem cells might be used to create new spinal cord
cells to replace damaged cells
– Heart disease:
• After a heart attack, part of the heart muscle dies. Stem cells
might be able to make heart muscle cells to replace the damaged
part of the heart.
– Crohn's disease:
• Stem cells could replace the misguided immune cells that attack
the digestive tract.
8-Which diseases could be treated with
stem cells? ….
– Genetic diseases:
• In many genetic diseases, there is a specific defect in
the genes. Stem cells that do not have this defect
could be used in their place.
•
9-Are stem cell treatments safe?
• That remains to be seen.
• Cancer is one of the big concerns, partly because stem cells
can go on dividing endlessly, which may lead to cancer. And,
as noted earlier in this article, using retroviruses to
"reprogram" adult cells to act like embryonic stem cells
could pose a cancer risk.
• Unfortunately, there is no way to know for sure without
actually doing stem cell treatments. Researchers will be
watching patients who receive stem cell treatments very
closely to see what risks arise.
10- What is somatic cell nuclear transfer
(SCNT)?
• Somatic cell nuclear transfer (SCNT) is a technique in which
the nucleus of a somatic cell, that is any cell of the body
apart from the sperm or egg, is transferred into an egg that
has had its original nucleus removed. The egg now has the
same DNA, or genetic material, as the donor somatic cell.
Given the right signals, the egg can be coaxed into
developing as if it had been fertilized. The egg would divide
to form 2 cells, then 4 cells, then 8 cells and so on until the
blastocyst is formed. Embryonic stem cells can be derived
from this blastocyst to create cell lines that are genetically
identical to the donor somatic cell.
11. Why derive embryonic stem cell lines following somatic cell
nuclear transfer (SCNT)?
• The derivation of patient-specific human embryonic stem
cell lines using this technique (see ‘What is somatic cell
nuclear transfer?’) Firstly, these cells could provide a
powerful new tool for studying the basis of human disease
and for discovering new drugs. Secondly, the resulting
embryonic stem cells could be developed into a needed cell
type, and if transplanted into the original donor, would be
recognized as 'self', thereby avoiding the problems of
rejection and immunosuppression that occur with
transplants from unrelated donors.
12. Can induced pluripotent cells replace research on
embryonic stem cells or somatic cell nuclear transfer?
• No. The derivation of human induced pluripotent stem cells
opens up exciting new areas of stem cell research, however,
this technology is at a very early stage and many
fundamental questions remain. While iPS cells and
embryonic stem cells share many characteristics they are not
identical. The similarities and differences are still being
explored.
•
‫تا سال ‪ 2004‬تقريبا ‪ 350‬مريض‬
‫پا ركينسوني تحت درمان با بافت‬
‫مزانسفاليك جنيني انسان يا خوك قرار‬
‫گرفته اند‪.‬در اين بيماران بافت ترانسپلنت‬
‫بيماران فلورو دوپا در ب شده باعث جذ‬
‫پاركينسوني در روش تصوير برداري‬
‫شد‪.‬يك مشكل در پيوند اين ميباشد ‪PET‬‬
‫كه بقا سلولهاي ترانسپلنت شده كم‬
‫ميباشد‪.‬وتنها ‪ 5‬تا ‪ 20‬درصد سلولها در‬
‫محل ضايعه باقي ميمانند‪.‬در مدلهاي‬
‫حيواني بقا سلولهاي ترانسپلنت شده با به‬
‫كار بردن فاكتورهاي رشد و مواد آنتي‬
‫اكسيدان افزايش يافته است‬
‫سلولهای بنيادی خون ساز‬
‫سلولهاي بنيادي بند ناف وسلولهاي بنيادي خارج جنينی‬
‫ديابت‬
‫مطالعات مختلفي براي تمايز سلولهاي‬
‫بنيادي مغز استخوان سلولهاس بنيادي‬
‫جنيني سلولهاي بنيادي پانكراس بالغين‬
‫سلولهاي بنيادي خون بند ناف به سمت‬
‫سلولهاي توليد كننده انسولين صورت‬
‫گرفته است‪.‬خصوصيات اين سلولهاي‬
‫بنيادي نشان داد كه اين سلولهاي بنيادي‬
‫قادر به پايين اوردن مقدار گلوكز خون‬
‫ميباشند‪.‬‬
‫مطالعات نشان داده است كه سلولهاي‬
‫بنيادي‬
‫كه از مجراي پانكراس بدست امده اند باعث‬
‫پايين آوردن مقدار گلوكز خون در‬
‫موشهاي ديابتي شده اند‪.‬‬
‫• خواهشمند است کاربران محترم نظرات اصالحی خود را به آدرس‬
‫‪ [email protected]‬و یا شماره تلفکس ‪ 7922517‬ارسال‬
‫فرمایند‪.‬‬