Where are therapeutic stem cells obtained from?

Answer 1

A stem cell is a cell that has the ability to continuously divide and differentiate (develop) into various other kind(s) of cells and tissues. Like a blank microchip that can ultimately be programmed to perform any one of a number of specialized tasks, stem cells are undifferentiated, 'blank' cells that do not yet have a specific physiological function. When the proper conditions occur in the body or in the laboratory, stem cells begin to develop into specialized tissues and organs. Stem cells are also self-sustaining, replicating through cell division.

These unique characteristics are why stem cell research holds such great promise for the treatment of life-threatening and debilitating diseases such as Alzheimer's disease, cancer, Parkinson's disease, and juvenile Diabetes. Understanding what the genetic and biochemical signs are that trigger stem cell differentiation may allow researchers to one day program new cells to repair damaged tissues and organs, and to better understand disease processes. Here is a current list of the sources of stem cells:

• Embryonic stem cells - They are harvested from the inner cell mass of the blastocyst seven to ten days after fertilization.
• Fetal stem cells - These cells are taken from the germline tissues that will make up the gonads of aborted fetuses.
• Umbilical cord stem cells - Umbilical cord blood contains stem cells similar to those found in bone marrow.
• Placenta derived stem cells - Up to ten times as many stem cells can be harvested from a placenta as from cord blood.
• Adult stem cells - Many adult tissues contain stem cells that can be isolated. The goals of stem cell research include curing diseases, cloning, and gene-line engineering. Cloning is directed towards making duplicate animals or humans. Gene-line engineering is directed toward permanent change in disease resistance and aesthetic and functional enhancements.

Answer 2

The practical definition of a stem cell is the functional definition - a cell that has the potential to regenerate tissue over a lifetime.

Commonly, stem cells come from two main sources:

• Embryos formed during the blastocyst phase of embryological development (embryonic stem cells).
• Adult tissue (adult stem cells).

In a developing embryo, stem cells can differentiate into all of the specialized embryonic tissues. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells, but also maintain the normal turnover of regenerative organs, such as blood, skin or intestinal tissues.

Adult or somatic stem cells exist throughout the body after embryonic development and are found inside of different types of tissue. These stem cells have been found in tissues such as the brain, bone marrow, blood, blood vessels, skeletal muscles, skin, and the liver. They remain in a non-dividing state for years until activated by disease or tissue injury.