By Dr Ananya Mandal, MD
Stem cells are mother cells that have the potential to become any type of cell in the body. One of the main characteristics of stem cells is their ability to self-renew or multiply while maintaining the potential to develop into other types of cells. Stem cells can become cells of the blood, heart, bones, skin, muscles, brain etc. There are different sources of stem cells but all types of stem cells have the same capacity to develop into multiple types of cells.
Stem cells (center ones) can develop into any cell type. They are valuable as research tools and might, in the future, be used to treat a wide range of diseases. Credit: Judith Stoffer
Types of stem cells
Pluripotent Stem Cells (PS cells)
These possess the capacity to divide for long periods and retain their ability to make all cell types within the organism. The best known type of pluripotent stem cell is the one present in embryos that helps babies grow within the womb. These are termed embryonic stem cells. These cells form at the blastocyst stage of development. A blastocyst is a hollow ball of cells that is smaller than a pinhead. The embryonic stem cells lie within this ball of cells. Recent research has enabled scientists to derive pluripotent cells from adult human skin cells. These are termed induced pluripotent stem cells or iPS cells.
Fetal stem cells
These are obtained from tissues of a developing human fetus. These cells have some characteristics of the tissues they are taken from. For example, those taken from fetal muscles can make only muscle cells. These are also called progenitor cells.
Adult stem cells
These are obtained from some tissues of the adult body. The most commonly used example is the bone marrow. Bone marrow is a rich source of stem cells that can be used to treat some blood diseases and cancers.
Discovery of stem cells
Scientists first studied the potential of stem cells in mouse embryos over two decades ago. Over years of research they discovered the properties of these stem cells in 1998. They found methods to isolate stem cells from human embryos and grow the cells in the laboratory.
Early studies utilized embryos created for infertility purposes through in vitro fertilization procedures and when they were no longer needed for that purpose. The use required voluntary donation of the embryos by the owners.
Potential for use
Stem cell research is improving by leaps and bounds. These may soon become the basis for treating diseases such as Parkinson's disease, diabetes, heart failure, cerebral palsy, heart disease and host of other chronic ailments.
Stem cells may also be used for screening new drugs and toxins and understanding birth defects without subjecting human volunteers to the toxins and drugs.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)