The Research and Advancement of Adult Stem Cell Transplants There are two major categories of stem cells: embryonic and adult. Human embryonic stem cells are derived from human embryos and remain controversial, while adult stem cells can be obtained from adult tissues, as well as tissue from children. During early life and growth, stem cells have the amazing ability to develop into many different cell types in the body. In addition, they serve as a sort of internal repair system in many tissues, dividing essentially without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell. Stem cells are distinguished from other cell types by two important characteristics. First, they are unspecialized cells capable of renewing themselves through cell division, sometimes after long periods of inactivity. Second, under certain physiologic or experimental conditions, they can be induced to become tissue or organ-specific cells with special functions. In some organs, such as the gut and bone marrow, stem cells regularly divide to repair and replace worn-out or damaged tissues. In other organs, however, such as the pancreas and the heart, stem cells only divide under special conditions (Harold 101). Studying stem cells will help us understand how they transform into the dazzling array of specialized cells that make us what we are. Some of the most serious medical conditions, such as cancer and birth defects, are due to problems that occur somewhere in this process. A better understanding of normal cell development will allow us to understand and perhaps correct the errors that cause these medical conditions (Langwith 27).
About 800 000 people in America suffer from a stroke annually, and around a quarter of them will suffer a second stroke. Stroke is the largest cause of disability and the third leading cause of death (after heart disease and cancer). The annual cost to treat victims in the United States is estimated by the Centers for disease control to at $37 billion, including the cost of healthcare services, medications, and missed days of work (Krimsky 55). A stroke can leave its victim with paralysis, permanent brain damage, cognitive impairment, loss of speech, and long-term disability. About 87% of strokes are classified as ischemic, meaning that a blocked artery interrupts the flow of blood and, thus oxygen to the brain. Each minute there is blood loss to the brain, an estimated 2 million brain cells die (Krimsky 55). Those cells cannot regenerate themselves. Scientists have developed strategies to regenerate damaged brain cells with stem cells. Large numbers of active stem cells are used in the re-growth of nerve tissue and brain cells, and, fortunately, most people have an ample supply. The patient's own stem cells...
