Stem Cells

1. a) Throughout our lives, we continue to rely on stem cells to replace injured tissues and cells that are lost every day, such as those in our skin, hair and blood. (NIH, 2009)

There are two different types of stem cells: embryonic stem cells and non-embryonic "adult" or "somatic" stem cells have been mainly worked with scientists. Human embryonic stem cells are derived primarily from blastocysts that were created by in vitro fertilization (IVF) for assisted reproduction but it will be for research purpose when it was no longer needed for vitro fertilization. (NIH, 2009)

Embryonic stem cells have the potential to generate every cell type found in the body. Just as importantly, these cells can be grown and expanded unlimitedly in this unspecialized state. These cells help researchers learn about early human developmental processes that are otherwise inaccessible, study diseases and establish strategies that could ultimately lead to therapies designed to replace or restore damaged tissues. (Kessler & Muro & Bonaguidi & Das, 2008)

b) (i) Produce embryonic stem cells

* Embryonic stem cells are derived from blastocysts-embryos that are about a week old. At this stage, the blastocyst has about 150 cells.

* In order to get embryonic stem cell lines, scientists remove cells from the inner cell cell mass region. These cells have the potential to develop into any type of cell in the body.

* Once the cells are removed, they are place on a culture plate with nutrients and growth factors. The blastocyst is destroyed in this process.

* An embryonic cell line is established when these cells multiply and divide. Under the right conditions, these cell lines can be maintained indefinitely. (Cherian & Kurian, 2011)

(ii) Techniques

There are three techniques used to harvest embryonic stem cells: somatic cell nuclear transfer (SCNT), altered nuclear transfer (ANT), and blastomere extraction.

Somatic Cell Nuclear Transfer (SCNT)

The nucleus of any somatic cell (except reproductive cells) is transferred into an egg cell, whose nucleus has also been removed. After the somatic nucleus is transferred into the egg cell, the host cell then reprograms the cell nucleus. This altered cell is then stimulated by shock and begins to divide producing a blastocyst. The blastocyst is destroyed between 5 and 7 days and stem cells are harvested for research purposes. (Mollard)

Altered Nuclear Transfer (ANT)

Altered nuclear transfer is a proposed technological approach to obtain embryonic stem cells without destroying the embryo. It can prevent an embryo from being formed. The adult body cell nucleus or the enucleated egg's contents are first altered before the adult body cell nucleus is transferred into the egg. The alternations cause the adult body cell DNA to function in such a way that no embryo is generated but pluripotent stem cells are produced. (Johnson, 2008)

Blastomere Extraction

In a paper in the November 2006 issue of Nature, Dr Lanza proposed that a single blastomere (cell) is removed from an eight-stage blastocyst (inner mass of the embryo) and is cultured to form an embryonic stem cell. This means the embryo itself is not harmed in any way and can go on to grow into a full human being without any problems. (Østnor, 2008)

(iii) How do scientists use embryonic stem cells

Have a better understanding of how diseases occur

By watching stem cells differentiate into mature cells, researchers and doctors may better understand how a disease arise and suggest new strategies for therapy. (Østnor, 2008)

Generate healthy cells to replace diseased cells

Researchers hope they can train stem cells into becoming specific cells so that those specialized cells can be used to regenerate and repair diseased or damaged tissues in people who might benefit from stem cell therapies include those with Parkinson's disease, Alzheimer's disease and Type 1 diabetes. Stem cells could also be grown to become new tissue for use in transplant medicine. (Korobkin & Munzer, 2007)

c) Research

Scientists reported that they had coaxed human embryonic stem cells into becoming insulin-producing, blood sugar-regulating cells in diabetic mice. (Lumelsky & Blondel & Laeng & Velasco & Ravin & Mckay, 2001)

Besides that, scientists also hope that stem cells could be used to grow organs like heart and kidney and overcome the shortage of organ donors. But, three dimensional growths of complex structural and functional entities have to figure out by a scientist which is how to develop this kind of culture techniques. (Mollard)

Researchers hope they can coax embryonic stem cells, and maybe also adult or cord blood stem cells, into producing cells and tissue for replacement therapies to treat diseases such as Parkinson's disease, heart attacks and blood disorders. (Mollard)

Assay the new drugs

The safety of new medications can be tested on differentiated cells derived from human pluripotent