A stem cell is a special kind of cell that has a unique capacity to renew itself and to give rise to specialized cell types. Although most cells of the body,such as heart cells or skin cells,are committed to conduct a specific function, a stem cell is uncommitted and remains uncommitted, until it receives a signal to develop into a specialized cell. Their proliferative capacity combined with the ability to become specialized makes stem cells unique. Researchers have for years looked for ways to use stem cells to replace cells and tissues that are damaged or diseased.
In 1998, for the first time, investigators were able to isolate the pluripotent stem cell from early human embryos and grow them in culture. In the few years since this discovery, evidence has emerged that these stem cells are ,indeed,capable of becoming almost all of the specilaized cells of the body and,thus,may have the potential to generate replacement cells for a broad array of tissue and organs,such as the heart, the pancreas,and the nervous system. Thus, this class of human stem cell holds the promise of being able to repair of replace cells or tissue that are damaged or destroyed by many of our most devasting disease and disabilities.
In 2003, Hwang et al published the their extraordinary results from researches of human embryonic stem cell. They established the autologous stem cells for patients from nuclear transferred embryo in human. This study opened the door of clinical application using embryonic stem cell without immune rejection. However, ethical problem is still devated and remained in the clinical application.
At about the same time as scientists were beginning to explore human pluripotent stem cells from embryos and fetal tissue, a flurry of new information was emerging about a class of stem cells that have been in clinical use for years-socalled adult stem cells. An adult stem cell is an undifferentiated cell that is found in a differentiated(specialized) tissue in the adult,such as blood. It can yield the specialized cell types of the tissue from which it originated. In the body,it too, can renew itself. During the past decade,scientists discovered adult stem cells in tissues that were previously not thought to contain them,such as the brain. More recently,they reported that adult stem cells from one tissue appear to be capable of developing into cell types that are characteristic of other tisues. For example, hemtopoietic stem cell from bone marrow or umbilical cord blood could develop into cells that have many of the characteristics of neurons. Hematopoietic stem cell can develop into cardiomyocytes. Recently, mesenchymal stem cell proliferation was established successfully from human umbilical cord blood.
Through upgraded worldwide researches, clinical application of stem cell is becoming the new trends of medicine. Now a day many physicians are trying to challenge onto the area of uncurable or difficult curable disease until now.
Hopely speaking, we believe that many patients suffering from various dysabilities eventhough discontinued effort of modern medical approaches, can be cured by this miraculous medicine at near future.