Tuesday, March 10, 2009

New Chapter in Stem Cell Therapy

Few recent scientific issues have stimulated so much media attention, public debate and government involvement as that of stem cell research. Stem cells offer people hope by promising to greatly extend the number and range of patients who could benefit from transplants, and to provide novel therapies to treat debilitating diseases such as diabetes, Parkinson’s, Huntington’s, heart disease and stroke, as well as accidental damage such as spinal cord injury.

Types of Stem Cell
What is meant by stem cells and how might they be used? There are many types of stem cell, but they share several interesting properties that set them aside from other cell types. The adult body contains hundreds of specialised or “differentiated” cell types, each playing a particular role. Some of these are long-lived and do not divide, such as nerve cells; others are short-lived and need to be replaced through cell division. Usually, when cells divide, their daughter cells are identical and of the same type as the parent cell. In other words they divide symmetrically. Additionally, their fate and their properties are fixed—once a liver cell, always a liver cell.

In contrast, stem cells undergo “asymmetric” divisions, producing both another stem cell, in a process called self-renewal, and a cell that will become differentiated. The differentiated cell may still be able to divide, but it cannot normally go back to form the original type of cell. In some circumstances stem cells can increase their numbers, giving rise only to more stem cells.

However, stem cells in the adult are usually in tune with the tissue to which they belong. They divide at the appropriate rate to self-renew and to give rise to just sufficient differentiated cells to replenish those that have been lost. However, with accidental trauma or disease the normal rate of regeneration is often too slow to allow for repair. This is particularly true within the nervous system, but also in other tissues where turnover is low, such as the pancreas.

Recent Breakthrough
The Centre for Stem Cell Research at Christian Medical College (CMC), Vellore has succeeded in reprogramming cells drawn from adult mice and making them function like stem cells found in the human embryo. It is a breakthrough that may have the country's medical and scientific community sitting up and taking notice.

This development has opened a new chapter in stem cell therapy in the country. With this breakthrough the technology can now be applied to generate similar stem cells from adult human cells too. These can be used to study genetic disorders relating to blood, muscle, brain and even diseases like diabetes. The use of embryos to draw stem cells has been the subject of a controversy, and the latest discovery may mean that embryos need not necessarily be used in the process. This is an important milestone for India in stem cell research and signifies a paradigm shift in the way diseases can be treated. We will now begin work on human cells to generate disease-specific induced pluripotent stem (iPS) cells to study hereditary diseases.

As far as India is concerned, this means once the researchers are able to take this on to human cells also; the country will not have to rely on external help for generating models for studying and treating human diseases. With regard to clinical significance, as anywhere else in the world, the researchers need to be very careful not to give an impression to people that this is going into human treatment anytime soon. It could be years before that happens and it will be only after the safety of use of such cells is clearly established.

iPS Technology
In February 2009, the Research Centre, supported by the Department of Biotechnology, Ministry of Science and Technology and CMC, was successful in generating in mice these ''induced pluripotent stem (iPS) cells'' which are similar to embryonic stem cells. Researchers will soon move on to generating similar cells from normal and diseased human cells. The organisation looks primarily at translational research--research that has potential for clinical applications.

Embryonic stem cells have great capacity for self-renewal and are used in regenerative medicine and tissue replacement. According to the researchers, iPS cells generated at the research centre may have the same potential. India is the fifth country, after the US, the UK, China and Japan, to achieve these results. The iPS technology is relatively new and acknowledged worldwide as the ''ultimate manufacturing process''. Scientists can now use the human skin or other cells like an assembly line to roll off cells that have the ability to adapt themselves to any tissue in the body that requires healing or replenishment.

Vats for Red Blood Cells
The US scientists at Massachusetts-based Advanced Cell Technology have made it clear that embryonic stem cells can be used to grow vats of red blood cells, which could lead to the creation of "farms" that could provide limitless sources of blood.

They think that the discovery might help save the struggling company, which is desperately seeking investors to keep it afloat. Stem cells are the body's master cells, replenishing various cells and tissues as they die. Stem cells taken from days-old embryos are especially powerful, with the ability to produce any cell type. Doctors hope to some day use them to provide tailor-made transplants for patients, and to study disease. One problem is that the immune system may reject tissues grown from someone else's stem cells. Red blood cells may be an exception to this, because they do not have a nucleus. What the scientists envision is growing batches of cells from human embryos possessing all the different blood types: A, B, O and AB, as well as negative and positive Rh versions of each. O negative, considered "universal" because it can be transfused safely into anyone possessing any of the other types, would be the most desirable. The ability to, on-demand, make as much as you want is obviously very, very attractive. The US Federal Government strictly limits its funding of embryonic stem cell research because of controversies over the use of human embryos.

Several clinical trials targeting heart disease have shown that adult stem cell therapy is safe and effective. Adult stem cell therapy for heart disease was commercially available on at least five continents at the last count.

US Lifts Ban on Stem Cell Research
The US President Barack Obama on March 9,2009 lifted the eight-year ban on funding of stem cell research. The decision will ensure that the US Government never opens the door to the use of cloning for human reproduction.

"It is dangerous, profoundly wrong, and has no place in the American society, or any society," Obama said as he promised to enforce a strict regulation with regard to stem cell research in the country.

The country will support it only when it is both scientifically worthy and responsibly conducted. We will develop strict guidelines, which it will rigorously enforce, because we cannot ever tolerate misuse or abuse

Existing Follicles
Hair follicles also contain stem cells, and some researchers predict research on these follicle stem cells may lead to successes in treating baldness through “hair multiplication”, also known as “hair cloning”, in the next couple of years. This treatment is expected to work through taking stem cells from existing follicles, multiplying them in cultures, and implanting the new follicles into the scalp. Later treatments may be able to simply signal follicle stem cells to give off chemical signals to nearby follicle cells which have shrunk during the ageing process, which in turn may respond to these signals by regenerating and once again making healthy hair.

Medical researchers widely submit that stem cell research has the potential to dramatically alter approaches to understanding and treating diseases, and to alleviate suffering. In the future, most medical researchers anticipate being able to use technologies derived from stem cell research to treat a variety of diseases and impairments.

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