Scientists could use stem cells to model disease processes in the laboratory, and better understand what goes wrong. Stem cells, either carrying the disease gene or engineered to contain disease genes, offer a viable alternative. In many cases it is difficult to obtain the cells that are damaged in a disease, and to study them in detail. Stem cells could be used to study disease This prospect is an exciting one, but significant technical hurdles remain that will only be overcome through years of intensive research. Stem cells, if they can be 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, stroke, heart disease and diabetes. Today, donated tissues and organs are often used to replace damaged tissue, but the need for transplantable tissues and organs far outweighs the available supply. Stem cells may also hold the key to replacing cells lost in many other devastating diseases for which there are currently no sustainable cures. This property is already used in the treatment of extensive burns, and to restore the blood system in patients with leukaemia and other blood disorders. Stem cells have the ability to replace damaged cells and treat disease This is an important goal of stem cell research. A better understanding of the genetic and molecular controls of these processes may yield information about how such diseases arise and suggest new strategies for therapy. Some of the most serious medical conditions, such as cancer and birth defects, are due to abnormal cell division and differentiation. Identifying the signals and mechanisms that determine whether a stem cell chooses to carry on replicating itself or differentiate into a specialized cell type, and into which cell type, will help us understand what controls normal development. In the laboratory, scientists can follow stem cells as they divide and become increasingly specialized, making skin, bone, brain, and other cell types. Stem cells may help us understand how a complex organism develops from a fertilised egg. Stem cells can be used to study development According to the classical view, as an organism develops, the potential of a stem cell to produce any cell type in the body is gradually restricted. Stem cells from different tissues, and from different stages of development, vary in the number and types of cells that they can produce. Stem cells can also divide and produce more specialized cell types. Specialized cells such as blood and muscle do not normally replicate themselves, which means that when they are seriously damaged by disease or injury, they cannot replace themselves. Self-renewal is the defining property of stem cells. This process is called self-renewal and continues throughout the life of the organism. Stem cells can divide and produce identical copies of themselves over and over again. Unlike a red blood cell, which carries oxygen through the blood stream, or a muscle cell that works with other cells to produce movement, a stem cell does not have any specialized physiological properties.

Pluripotent stem cells