What are Stem Cells anyway???

Stem cells are cels that have the ability to divide for indefinite periods in culture and to give rise to specialized cells.

The fertilized egg in a human being is totipotent meaning its potential is total- it can form an entire organism. In the first few hours after fertilization it divides into identical totipotent cells. Approximately four days after fertilization, the blastocyst is formed which as we know has the outer and inner cell mass. The outer cell mass forms the placenta and the inner cell mass forms virtually all the tissues in the body.

These inner cell mass cells are pluripotent-they can give rise to many types of cells but not all types of cells necessary for fetal development. The pluripotent cells undergo further specialization to committed stem cells which have a particular function- example- blood stem cells give rise to blood cells of all types. These more specialized cells are in other words multipotent.

How are they derived ?

At present there are two sources of pluripotent stem  cells

 1)Isolation directly from the inner cell mass of human embryos at the blastocyst stage. ( The most controversial method) :

The embryos are from IVF (the ones in excess of the clinical need in infertility treatment)

2) Isolation from fetal tissue obtained from terminated pregnancies.This could be done….

3) The use of somatic cell nuclear transfer (SCNT) may be another way that pluripotent cells could be isolated. In short, the nucleus of a human somatic cell is injected into an empty animal ovum. One major advantage is – we can avoid immune rejection- the nucleus can be from the patient himself.

What will they be used for ?

1) For the better understanding of certain disease conditions :
Some of our serious medical conditions like cancer and birth defects are due to errors in the “decision making” process. A better understanding of the off-on mechanism will help us to further better research in these areas.

2) Drug development:
New medications could be tested on human cell lines, the advantage in using stem cells being that the drugs can be tested in a wide variety of cell

3) “Cell therapies”:
 They may act as a source of renewal and replenishment by developing into specialized cells.

Examples of Cell therapy include-
- Transplant of healthy heart muscles in patients of chronic heart disease
- Transplantation of isolated islet cells into the pancreas of Type 1
Diabetes patients.
- Transplantation of stem cells into the brain of patients with Parkinson’s disease leading to production of dopamine.
- Persons with severe spinal cord injuries could possibly receive regenerative cell transplants directly into the spine with little invasive surgery.
- Cancer chemotherapy patients can benefit from stem cell therapy which will help them to regenerate healthy blood cells.

Diseases in which stem cell (adult) therapy has been tried include almost all the leukemias, sickle cell anemia, myeloproliferative disorders, lymphoproliferative disorders, liposomal storage diseases, Thalassemia major, Multiple myeloma, neuroblastoma, Ewing sarcoma, renal cell carcinoma and many others.