Stem cells

By Sheena Scroggins

Biological Foundationshttp://yorkstudentrn.files.wordpress.com/2009/03/stem_cell1.jpg

What are stem cells?

• Stem cells are cells that can proliferate or self-renew into many different types of specialized cells.

http://www.jforsythe.com/jforsytheblog/content/binary/embryonic_stem_cell_chart.gif

Different types of stem cells

• A stem cell's potency is its ability to become to other cells in the body. These include:

• Totipotent stem cells: can differentiate into any type of cell in the human body, including the placenta.

• Pluripotent stem cells: they descend from totipotent stem cells and after several days, can differentiate into any type of cell except for totipotent stem cells.

• Multipotent stem cells: these descend from pluripotent stem cells and can differentiate into many cell lines within a specific type of tissue.

• Unipotent stem cells: this type of stem cells is a descendant of a multipotent stem cell and can give rise to a single cell type.

http://en.wikipedia.org/wiki/File:Stem_cells_diagram.png

Key Achievements in Stem Cell Research

1981 - Mouse embryonic stem cells are derived from the inner cell mass

1992 - Neural stem cells are cultured in vitro as neurospheres.

1997 - Leukemia is shown to originate from a haematopoietic stem cell, the first direct evidence for cancer stem cells.

1998 - First human embryonic stem cell line derived.

2000s - Several reports of adult stem cell plasticity are published.

2001 - Scientists clone first early (four- to six-cell stage) human embryos for the purpose of generating embryonic stem cells..

October 2006 - Scientists create the first ever artificial liver cells using umbilical cord blood stem cells

January 2007 - Scientists report discovery of a new type of stem cell in amniotic fluid

June 2007 - Research reported by three different groups shows that normal skin cells can be reprogrammed to an embryonic state in mice.

June 2007 Scientist reports the first successful creation of a primate stem cell line through somatic cell nuclear transfer .

Key Achievements Continued

October 2007 - Mario Capecchi, Martin Evans, and Oliver Smithies win the 2007 Nobel Prize for Physiology or Medicine for their work on embryonic stem cells from mice using gene targeting strategies producing genetically engineered mice for gene research.

November 2007 - Human induced pluripotent stem cells are created, making it possible now to produce a stem cell from almost any other human cell instead of using embryos as needed previously, albeit the risk of tumorigenesis due to c-myc and retroviral gene transfer remains to be determined.

January 2008 - Scientists create the first human embryonic stem cells without destruction of the embryo

January 2008 - Development of human cloned blastocysts following somatic cell nuclear transfer with adult fibroblasts

February 2008 - Generation of pluripotent stem cells from adult mouse liver and stomach.

March 2008-The first published study of successful cartilage regeneration in the human knee using autologous adult mesenchymal stem cells is published.

October 2008 – Generation of pluripotent stem cells from spermatogonial cells of adult human testis by culturing the cells in vitro under leukemia inhibitory factor (LIF) supplementation.

October 2008 - Embryonic-like stem cells from a single human hair.

Key Achievements Continued

March 2009 - Scientists discover a way to produce embryonic-like stem cells from normal adult cells by using a novel "wrapping" procedure to deliver specific genes to adult cells to reprogram them into stem cells without the risks of using a virus to make the change.

March 2009 Scientists find a way to improve chemotherapy of mouse muscle stem cells.

May 2009 Scientists announced that they had devised a way to manipulate skin cells to create patient specific "induced pluripotent stem cells" (iPS), claiming it to be the 'ultimate stem cell solution'.

Current Stem Cell Treatments

Stem cells are currently being used in a few different therapies. These include:

• Parkinson's disease

• Type I diabetes

• Arthritis

• Burn victims

• Cardiovascular diseases

http://stemcells.nih.gov/staticresources/info/media/DSC_1185.jpg

Problems with Stem Cell Therapy

• Passing on Viruses- A possible concern is that stem cell therapy could pass on viruses or other microscopic agents that cause disease. Patients who are receiving transplants often take strong drugs that essentially 'wipe out' their immune system. This is to reduce the chances of their body rejecting a transplant. The flip side is that if any viruses are present in the transplanted stem cells, a patient's immune system is completely vulnerable to disease.

: www.topnews.in/healthcare/general/featured?page=4

More Problems

Diseases From Other Animals- Animal sources may be used to provide nutrients to stem cells that are being cultivated in the laboratory. These sources could contain various diseases that may then be passed on to humans receiving cell-based therapies. A concern is that screening is currently insufficient to detect known diseases that may be present. Also, there may be diseases we are still yet unaware of that could be passed on to humans.

susty.com/swine-flu-roundup-spring-2009/

More Problems

Uncontrolled Growth- One concern with embryonic stem cells is related to the very quality that makes them so useful and versatile. Embryonic stem cells are 'young' cells and tend to grow quickly; the fast growth must, however, be carefully guided by scientists. These stem cells need to be cultivated and directed into specialized cells with great care because the potential for remaining stem cells to grow uncontrolled could be disastrous. These uncontrolled cells could eventually form tumors.

http://health.howstuffworks.com/cure-for-cancer-virus1.htm

More Problems

• Misdirected Growth- The possibility of transplanted stem cells differentiating into the wrong type of tissue is yet another concern regarding therapeutic stem cell use. Once stem cells are cultivated in a laboratory, researchers need to control and direct their growth into desired tissue cells. Scientists are attempting to overcome this problem by inducing partial stem cell differentiation prior to transplanting it into a patient. This would hopefully limit the capacity of the cells to differentiate into undesired tissue types once implanted. At present, scientists still know very little about how stem cell differentiation is controlled

http://www.bbc.co.uk/liverpool/content/image_galleries/skinterface_fact_gallery.shtml

http://www.stemcelltherapy21.com/stemcelltherapy21/stemcells/stem_cell_therapy.html

References

http://www.explorestemcells.co.uk/StemCellsFacts.html

http://en.wikipedia.org/wiki/Stem_cell -Key achievements

http://yorkstudentrn.files.wordpress.com/2009/03/stem_cell1.jpg

http://www.jforsythe.com/jforsytheblog/content/binary/embryonic_stem_cell_chart.gif

http://en.wikipedia.org/wiki/File:Stem_cells_diagram.png

http://stemcells.nih.gov/staticresources/info/media/DSC_1185.jpg

http://www.stemcelltherapy21.com/stemcelltherapy21/stemcells/stem_cell_therapy.html