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Few other ongoing areas of research have been the focus of so many articles and ethical debates played out in the national media, than stem cells. The topic has even been subject to presidential and congressional scrutiny. This on-going focus on stem cells is due in part to its amazing potential and the controversial nature of one type of stem cell, "the embryonic stem cell". Here, Balaji K of healthcare analysts Frost & Sullivan (http://pharma.frost.com) looks at the issue.

What are Stem Cells?
Stem cells are pluripotent in nature, meaning that they have the potential to develop into almost all, of the more than 200 known cell types. There are many kinds of stem cells in the human body, though some are more differentiated to a particular function than others. Thus the term stem cells "is commonly used to refer to the cells within the adult organism that renew tissues."

First isolated in 1997 by researchers at the Johns Hopkins Medical Institutions, the embryonic stem cell is a fairly recent addition to the list of stem cell types. Embryonic stem cells are unlike any adult stem cell. They are only found naturally in the early stages of embryonic development and are totipotent i.e. they can form any type of adult cell or adult cell precursor. Another type of stem cell, which has properties similar to the embryonic stem cell, is the embryonic germ cell.

An embryonic stem cell is derived from a group of cells called the inner cell mass, which is part of the early (4 to 5 day old) embryo called the blastocyst. Once removed from the blastocyst, the cells of the inner cell mass can be cultured into embryonic stem cells. These embryonic stem cells are not themselves embryos.

An embryonic germ cell is derived from fetal tissue. Specifically, these cells are isolated from the primordial germ cells of the gonadal ridge of the 5 to 10 week old fetus. Later in the development cycle, the gonadal ridge develops into the testes or ovaries and the primordial germ cells give rise to eggs or sperms.

Potential Applications
Transplantation Research: Stem cells may hold the key to replacing cells lost in many devastating diseases. Parkinsons disease, diabetes, chronic heart disease, end-stage kidney disease, liver failure, and cancer are just a few of the diseases for which stem cells have therapeutic potential. Despite recent advances in transplantation science, there is an ongoing shortage of donor organs. The growing demand for lifesaving organ replacements is unlikely to be met through organ donation strategies.

A major focus of research today is to use stem cells to generate replacement tissues for treating neurological diseases. Spinal cord injury, multiple sclerosis, Parkinson's disease, and Alzheimers disease are among those diseases for which the concept of replacing destroyed or dysfunctional cells in the brain or spinal cord is a practical goal. Another major research area on adult and embryonic stem cells is the development of transplantable pancreatic tissues that can be used to treat diabetes. Scientists in academic and industrial research are vigorously pursuing all possible avenues of research, including ways to direct the specialization of adult and embryonic stem cells to become pancreatic islet-like cells that produce insulin and can be used to control blood glucose levels. Researchers have recently shown that a human embryonic stem cell can be directly differentiated into cells that produce insulin.

Basic Research Applications: Embryonic stem cells will undoubtedly be the key research tools for understanding fundamental events in embryonic development that one day may explain the causes of birth defects and provide the approaches to correct or prevent them. Another important area of research that links developmental biology and stem cell biology is understanding genes and molecules, such as growth factors and nutrients, that function during the development of the embryo so that they can be used to grow stem cells in the laboratory and direct their development into specialized cell types.

Therapeutic Delivery Systems: Stem cells are already being explored as a vehicle for delivering genes to specific tissues in the body. Stem cell-based therapies are a major area of investigation in cancer research. For many years, restoration of the blood and immune system function has been used as a component in the care of cancer patients who have been treated with chemotherapeutic agents. Now, researchers are trying to devise more ways to use specialized cells derived from stem cells to target specific cancerous cells and directly deliver treatments that will destroy or modify them.

Other Applications of Stem Cells: Future uses of human pluripotent cell lines might include the exploration of the effects of chromosomal abnormalities in early development. This might include the ability to monitor the development of early childhood tumors, many of which are embryonic in origin. Another future use of human stem cells and their derivatives includes the testing of candidate therapeutic drugs. Although animal model testing is a mainstay of pharmaceutical research, it cannot always predict the effects that a developmental drug may have on human cells. Stem cells will in all probability be used to develop specialized liver cells to evaluate drug-detoxifying capabilities and could represent a new type of early warning system to prevent adverse reactions in patients. The coupling of stem cells with the information learned from the human genome project is also likely have many unanticipated benefits in the future.

The Future
Most of the evidence, that stem cells can be directed to differentiate into specific types of cells suitable for transplantation, (for example, neurons, heart muscle cells, or pancreatic islet cells), comes from experiments with the stem cells of mice. Though much is known about mouse stem cells, not all of that information can be translated to the understanding of human stem cells. Another important aspect of developing therapies based on stem cells will be devising ways to prevent the immune system of recipients from rejecting the donated cells and tissues that are derived from human pluripotent stem cells.

Background
Frost & Sullivan is an international marketing consulting company that monitors a comprehensive spectrum of healthcare markets for trends, market measurements and strategies. This on-going research is utilised to complement a series of research publications to support industry participants with customised consulting needs.

Frost & Sullivan will be shortly releasing a white paper on World Emerging Stem Cell Applications (A091-52).

For more information contact:
Nikki Cole
nikki.cole@fs-europe.com
Tel. +44 (0) 20 7343 8325
http://pressroom.frost.com

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