About Stem Cells
About Stem Cells
Stem cell science is an extremely fast moving field of research with new breakthroughs being reported almost daily. This swiftly changing landscape has seen many different stem cell types and technologies capture the public's imagination including embryonic stem cells, tissue stem cells, umbilical cord blood stem cells, and more recently, induced pluripotent stem cells. But what are stem cells and what makes them so interesting?
The human body is made up of over 200 different kinds of specialised cells such as muscle cells, nerve cells, fat cells and skin cells. All specialised cells originate from stem cells.
Stem cells are different from other cells in the body in two main ways:
- Stem cells are capable of self-renewal. Stem cells are able to divide and produce copies of themselves.
- Stem cells can differentiate. They can divide and produce cells that have the potential to become other more specific cell types, tissues or organs. These new cells and tissues can repair or replace damaged or diseased cells in the body. Stem cell differentiation is an essential part of normal growth, development and repair of injury and aging. Any compromise in stem cell function can have a significant impact on health
The question that intrigues medical researchers is whether you can harness the regenerative potential of stem cells and be able to grow new cells for treatments to replace diseased or damaged tissue in the body.
Stem cells can be divided into two broad groups: tissue specific stem cells (also known as adult stem cells) and pluripotent stem cells (including embryonic stem cells and iPS cells).
Tissue specific stem cells are derived from, or resident in, adult tissues, and can usually only give rise to the cells of that tissue, thus they are considered multipotent. Embryonic stem cells, derived from a small group of cells in the early embryo (5-7 days), are undifferentiated and are considered pluripotent as they can become every type of cell in the body.
What are Induced Pluripotent Stem Cells (iPS cells)
In 2006, scientists in Japan announced they had developed a new way to make pluripotent stem cells directly from an adult cell. These cells are referred to as induced pluripotent stem (iPS) cells, because they are induced, into becoming stem cells by modifying the activity in the cell’s genes.
Currently, iPS cells are generated from an adult cell by reactivating a small number of genes, turning the mature specialised cells back into pluripotent stem cells (a process called reprogramming). Although the mechanism by which these genes cause adult cells to become pluripotent is not yet fully understood, the technique holds great promise for stem cell research and regenerative medicine.
What do iPS cells offer?
If they are able to be made safely, and on a large scale, iPS cells could possibly have the same therapeutic potential as any form of pluripotent stem cell, providing a source of cells for replacement and regeneration after damage due to disease, injury, congenital (birth) defects or normal ageing.
This technology also allows scientists a new method of creating disease specific cells for research by creating iPS cells from the adult cells of a patient with a genetic disorder, such as Huntington’s disease. Studying these disease specific stem cells may improve our understanding of certain diseases, and assist in the development and testing of new drugs.
Reprogramming technologies are also of great interest to scientists as they represent ways to potentially create patient specific stem cells that could provide replacement cells to treat a patient which would not be rejected by the immune system. However, reprogramming research is in the very early stages and many years away from a therapeutic use.
About Regenerative Medicine
Modern strategies in regenerative medicine and tissue engineering have greatly employed the use of biomaterials with tailored biophysical and biochemical milieus that direct cellular behaviour and functions. Their incorporation of synthetic polymers and selected biological cues has the potential to provide a provisional three-dimensional support to interact with cells that can aid in tissue formation or regeneration, and thereby produce a therapeutic or diagnostic benefit.
Here, materials have been carefully designed to offer support for colonization, migration, growth and cell differentiation, as well as offer the spatial guide for cells and newly formed tissue and provide them with much needed mechanical support in the early stages of regeneration.
References and links
Yu J, Vodyanik MA, Smuga-Otto K, Antosiewicz-Bourget J, Frane JL, Tian S, Nie J, Jonsdottir GA, Ruotti V, Stewart R, Slukvin II, Thomson JA. Induced pluripotent stem cell lines derived from human somatic cells. Science, 2007, vol 318, pp1917-20.
Takahashi K, Tanabe K, Ohnuki M, Narita M, Ichisaka T, Tomoda K, Yamanaka S..Induction of pluripotent stem cells from adult human fibroblasts by defined factors. Cell. 2007, vol 131(5), pp861-72.
Research Involving Human Embryos Act 2002 and the Prohibition of Human Cloning for Reproduction Act 2002 as found at http://www.comlaw.gov.au