الفهرس 
Chapter(I): Introduction about stem cellOnly 14 pages are availabe for public view
 |  | from | 109 |  |  |
| | | from | 109 | | |
Abstract
In the face of extraordinary advances in the prevention, diagnosis, and treatment of human diseases, devastating illnesses such as heart disease, liver diseases, diabetes, cancer, and diseases of the nervous system, such as Parkinson’s disease and Alzheimer’s disease continue to deprive people of health, independence, and well-being. Research in human developmental biology has led to the discovery of human stem cells, including embryonic stem (ES) cells, embryonic germ (EG) cells, and adult stem cells.
The use of stem cells and tissue engineering represents a new era which is an important therapeutic attempt that is going to increase dramatically in the future. Although stem cell technologies are currently in the initial stages of development; there is tremendous promise in their potential to be of significant therapeutic benefit, the encouraging results that have been observed to date underscore the potential of this therapy, and despite limitations that may make immediate clinical implementation impractical; continuous study of various physical and chemical stimuli that alter the microenvironment of these cells both in vitro and in vivo will better define a role for tissue engineering .
There are many potential sources for stem cells. And can be grown and transformed into specialized cells with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture, their use in medical therapies has been proposed. In particular, embryonic cell lines, autologous embryonic stem cells generated through therapeutic cloning, and highly plastic adult stem cells from the umbilical cord blood or bone marrow are touted as promising candidates.
Recently, techniques have been developed for the in vitro culture of stem cells, providing promising opportunities for studying and understanding human embryology. As a result, scientists can now carry out experiments aimed at determining the mechanisms underlying the conversion of a single, undifferentiated cell, the fertilized egg, into the different cells comprising the organs and tissues of the human body. Although it is impossible to predict the outcomes, scientists and the public will gain immense new knowledge in the biology of human development that will likely hold remarkable potential for therapies and cures.
Today, donated organs and tissues are often used to replace destroyed tissue, but the need for transplantable tissues and organs far outweighs the available supply. Stem cells, directed to differentiate into specific cell types, offer the possibility of a renewable source of replacement cells and tissues to treat diseases including Parkinson’s and Alzheimer’s diseases, spinal cord injury, stroke, burns, heart disease, liver tumors post hepatectomy, liver cell failure, diabetes, osteoarthritis, and rheumatoid arthritis.
To realize the promise of novel cell based therapies for such pervasive and debilitating diseases, scientists must be able to easily and reproducibly manipulate stem cells so that they possess the necessary characteristics for successful differentiation, transplantation and engraftment.
The following is a list of steps in successful cell based treatments that scientists will have to learn to precisely control to bring such treatments to the clinic. To be useful for transplant purposes, stem cells must be reproducibly made to:
• Proliferate extensively and generate sufficient quantities of tissue.
• Differentiate into the desired cell type(s).
• Survive in the recipient after transplant.
• Integrate into the surrounding tissue after transplant.
• Function appropriately for the duration of the recipient’s life.
• Avoid harming the recipient in any way.