Stem Cells

Stem Cells are the basis of all very complicated life forms. Stem cells develop the fertilized egg, in time creating all of the bone, organs, and tissue. In adults, stem cells mostly just repair worn-out cells or create new ones. Therefore, there are two types of stem cells:
-embryonic (fertilized egg) stem cells (Picture 1)
-somatic (adult) stem cells  (Picture 2)
There are many stem cells in the embryo, and they are all unspecialized, meaning that they could become any of the cells found in a developed baby.
In adults, stem cell are spread out throughout the body and have more specialized choices in terms of what cells they can become (e.g. bone marrow stem cells primarily become blood cells).
Stem cells are different from normal cell because of two of their unique characteristics:
-they are capable of renewing themselves through cell division
-they can be induced to become tissue or organ-specific cells with special functions
                                                      Picture 1 (embryonic stem cells)

                                                              Picture 2 (adult stem cells)

Apart from their basic functions, stem cells can also be used to test new medication, and, more importantly, for therapeutic purposes (because of their regenerative properties).
One therapeutic purpose of stem cells is curing c.v.d. (cardiovascular disease). There has been research into this field, but only modest improvements have been mad when it comes to human testing. The biggest problem is that the heart, after being damaged, stops signaling the need for new (or repaired) heart cells after around a week or so. But, the Cleveland Clinic  says that scientist are try some new ways of stem cell therapy when it comes to c.v.d.:
"-giving more highly selected stem cells from a donor around the time of a heart attack
 -giving a patient's own cardiac stem cells later after a heart attack
 -giving highly selected, non-cardiac, stem cells from a donor later after a heart attack"
Regardless of the small successes this therapy is a long way from being proven fully safe and beneficial.
As mentioned, embryonic stem cells have the biggest potential, and because of that, a lot of research has been made into the conditions needed for embryonic stem cells to become specific cells. In order to extract embryonic stem cells, the fertilized egg cell (specifically blastocyst) has to be destroyed after 5-7 days of life. This has led to a lot of political and ethical issues all around the world, as many religious people (more in America) believe that life begins at conception, and that the fertilized egg cell has all the rights a person has. All of the cells are of course donated by couple who, simply put, don't want them. These embryonic stem cells are mostly used in research regarding progressively degenerative diseases such as Parkinson's or Huntington's. While it is true that a fertilized egg cell has the potential of becoming a person, it is also needed to think about the person on the other end. Even though a potential person is destroyed, a person that didn't get to fully be a person and enjoy life, may potentially get a chance at becoming healthy again. While it is hard to look at a fertilized egg as a simple clump of cells, I believe that the cause justifies the means when it comes to embryonic stem cell research.


http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2726839/
http://stemcells.nih.gov/info/basics/pages/basics1.aspx

Stem Cell KKesic

A stem cell is a multicellular organism which is capable of giving rise to more cells of the same type, from this some other kinds of cells arise by differentiation.
A new animal life is formed when a sperm fertilizes an egg cell to produce a zygote.When a zygote divides into two cells and embryo is formed. The two celled embryo divides to form a four cell embryo then eight, sixteen,etc. During these early stages cells divide to form a large amount of tissue. They are extremely versatile and can differentiate at different pathways into any of the cell types found in that particular animal. In the 19th century, the name of the zygote and cells of the early embryo was stem cell which meant that all tissues of the adult stem was form them.

Figure 1: Stem cell 

Stem cells can be used to regenerate tissue, for example skin for people that suffer from burns-skin stem cells. Stem cells could provide means of healing disorders.As well, it could be used to treat children with cancerous blood disorders such as leukaemia, blood diseases like Faconi anaemia. Cord blood stem cells are harvested from the umbilical cord of the baby after birth and these cells can be frozen in cell banks which make the treatments for specific problems, which are listed above, possible and curable.  For bone marrow mesenchymal stem cells regenerate tissue. Stem cells help repair type 1 diabetes where a particular cell type has been grown or it is malfunctioning ( Biology Course Companion Oxford pg. 13). It can also repair the cornea in the eye. Stem cells could also repair spinal cord injuries, autism, cerebral palsy, heart faliure, osteoarthiritis, etc.

Figure 2: Stem cell therapies 

The embryo gets destroyed during the process of cell derivation. According to some people it is unethical to technically destroy life because it is in a way disrespecting because it is given a status for the "human embryo to have the same moral status as a human being that has been born".