A Breakthrough In Adult Stem Cell

ResearchSATARUPA DEBDept Of Life Science & Bioinformatics,Assam University.

What are stem cells?Why should we study them?

Stem cells are “undifferentiated biological cells that can differentiate into specialized cells and can divide (through mitosis) to produce more new stem cells”.

“They are blank cells/precursor cells that can give rise to multiple tissue types such as skin cells, muscle cells, nerve cells and much more”.

Two basic types of stem cells:Embryonic stem cells & Adult stem cells

1. EMBRYONIC STEM CELLS

ADVANTAGES:-They are flexible.They are immortal.They can be used for extensive research purposes.

DISADVANTAGES:-Difficult to differentiate uniformly.Immunogenic.Tumerogenic.Destruction of developing human life.

“They are derived from embryos”.

2. ADULT STEM CELLS

“These stem cells are found in the umbilical cord (after live birth), fat, bone marrow, tissue, organs, blood, etc. of a human being. These cells can be removed from the body of the patient and manipulated in the laboratory.”

ADVANTAGES:-Stem cells from bone marrow & umbilical cords appear to be flexible as ECS.Not immunogenic.Relative ease of procurement.

DISADVANTAGES:-Limited quantity.Finite.

Important features of stem cells 1. Stem cells have the amazing ability to develop into several distinct cell types in the body. When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell, with a more specialized function.

2. Stem cells can be used as a repair system for the body.

3. A stem cell is “uncommitted”, until it receives a signal to develop into a specialized cell.•There are signals inside and outside cells that trigger stem cell differentiation.• The internal signals are controlled by a cell’s genes.•The external signals include chemicals secreted by other cells, physical contact with neighbouring cells, and certain molecules in the microenvironment.

4. Stem cells exist in both embryos and adults.

Stem cells according to their potential to differentiate into another cell types can be of the

following categories: Pluripotent Stem Cells:- Can become many, but not all types of cells.

Totipotent Stem Cells:- Can become all types of cells.

Multipotent Stem Cells:- Can only become some types of cells.

Stem Cell Research

The 2012 Nobel Prize for Physiology and Medicine was honourably received by the two scientists, John Gurdon and

Shinya Yamanaka, who discovered that “mature specialized cells can be reprogrammed to become immature cells

capable of developing into all tissues of the body, or the organism itself.”

Dr. Gurdon’s Work

In 1962, Dr. Gurdon produced living tadpoles from the adult cells of a frog.The technique included:-Extraction of cell nucleus containing the frog’s DNA. Injection of the nucleus into another frog egg whose own nucleus had been removed. CONCLUSION:-

The egg was evidently able to reprogram the introduced nucleus and direct its genes to switch from the duties of an intestinal cell to those appropriate to a developing egg.

But How Did The Egg Cell Accomplish This Reprogramming Capability?????

The answer had to wait for 44 years.....

Dr. Yamanaka’s work

Working with mice, Dr. Yamanaka discovered in 2006 that the reprogramming can be accomplished by just four specific gene control agents in the egg. The agents, now known to biologists as ‘Yamanaka Factors’, are proteins made by master genes to regulate other genes.By injecting the 4 agents into an adult cell, he showed that it is possible to make the cell walk back to its primitive form (stem cell form).

Stem cells generated by this method are called as induced pluripotent cells or iPS cells.

POTENTIAL APPLICATION OF STEM CELL RESEARCH

Stem cells have the ability to replace damaged cells and treat disease:This property is already used in the treatment of extensive burns, and to restore the blood system in patients with leukaemia and other blood disorders.

Stem cells could be used to study disease:Some of the most serious medical conditions, such as cancer and birth defects, are due to abnormal cell division and differentiation. A better understanding of the genetic and molecular controls of these processes may yield information about how such diseases arise and suggest new strategies for therapy. This is an important goal of stem cell research.

Stem cells could provide a resource for testing new medical treatments:New medications could be tested for safety on specialized cells generated in large numbers from stem cell lines – reducing the need for animal testing. Other kinds of cell lines are already used in this way. Cancer cell lines, for example, are used to screen potential anti-tumor drugs.Most other recent laboratory techniques such as cloning and transplantation are based on stem cells.

ReferenceTuch BE (2006). "Stem cells—a clinical update". Australian Family Physician 35 (9): 719–21. PMID 16969445

Liu, et al. (2008). “Yamanaka factors critically regulate the developmental signaling network in mouse embryonic stem cells”. Cell Research. 18:1177–1189. doi: 10.1038/cr.2008.309

http://www.nobelprize.org/nobel_prizes/medicine/laureates/2012/press.html

http://www.eurostemcell.org/faq/what-are-potential-applications-stem-cell-research

https://www.youtube.com/watch?v=8JTw2RpDo9o

https://www.youtube.com/watch?v=9-9pSLQW2Ts