What are Stem Cells?

Stem cells are unique cells in the body distinguished by their two unique characteristics;

  • self renewal - or the ability to produce more stem cells, and
  • differentiation - the ability to produce mature cells of various types.

These unique properties ensure that when a stem cell divides each new cell has the potential to either remain a stem cell or to develop into another more specialised type of cell, thereby allowing the body to maintain healthy tissue as well as repairing or replacing damaged or worn out cells and tissue.

It is on the basis of these regenerative abilities that stem cells show almost unlimited potential for treating a wide range of diseases and the challenge now is to understand how to use these cells for future cell based therapies.

Stem cells may be classified as embryonic i.e. those cells collected from the very early embryo (just a few hundred cells) which are able to differentiate into all of the cells of the body.  Cord blood stem cells, because they are derived from a developed individual, are classified as a type of adult stem cell, however, cord blood stem cells differ from other types of adult stem cells in a number of ways.

  • Growth potential - cord blood stem cells grow faster and for longer than stem cells from other adult sources.
  • Aging - all cells in the body have a type of "internal clock" which limits how many times they can divide.  Because these cells are collected at the very earliest stage of life, this clock is set at a much earlier point.
  • Damage - as we go through life our cells are continuously being exposed to damage from radiation, chemicals etc.  At the time of birth this exposure is minimised; both because of protection by the mother and simply because the cells have had less time to acquire damage.
  • Immune tolerance - one of the complications of haematopoietic stem cell transplants is that the stem cells can attack the patient's tissues (Graft vs Host disease).  Because these stem cells are collected prior to maturity of the immune system, this is much less of a problem with cord blood.
 
 
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