Stem cells are undifferentiated cells that can differentiate into specialized cells and can divide to produce more number of undifferentiated cells. They are found in multicellular organisms. In mammals stem cells are broadly clasified into two types: embryonic stem cells and adult stem cells. Embryonic stem cells are extracted from the inner cell mass of blastocysts and adult stem cells are present in various tissues of an adult. In adults the stem cells and progenitor cells act as a repair system for the body thereby replenishing adult tissues. In a developing embryo stem cells differentiates into three germ layers namely ectoderm, endoderm and mesoderm. They also maintain the normal turnover of regenerative organs such as blood skin or intestinal tissues.
The most common three sources of adult stem cells in humans are viz Bone marrow, adipose tissue and blood. stem cells can be harvested from bone marrow by extraction, that is, From adipose tissue or lipid cells, they can be extracted by liposuction and from it can be extracted through pheresis, where the blood is drawn from the donor similar to a blood donation and is passed through a machine which extracts the stem cells and returns other portions of the blood to the donor. Stem cells can also be taken from umbilical cord blood just after birth of a child. Of all the stem cell extraction types autologous harvesting involves the least risk.
Last date updated on July, 2014