2 Where are stem cells found in the body? In most body tissues - Adult tissue, embryos formed during blastocyst phase of embryological development - eg liver, skin, nerves.
3 Totipotent - A stem cell which has the potential to create any type of cell necessary for embryonic development including the embryo itself, and all of the membranes associated with embryonic development eg placenta.
Pluripotent - Stem cells that can give risento many, but not all cell types necessary for foetal development eg gives rise to foetal tissues but not placental tissues.
Multipotent - Stem cells that give rise to cells that have a particular function eg blood stem cells give rise to red and white blood cells and platelets.
Oligopotent - Stem cells which have potential to be differentiated into two or more types of cells in a tissue eg lymphoid stem cells.
Unipotent - Can give rise to singlemtypes of cells ( uni=one ) eg liver cells.
4 What are the differences between embryonic and adult stem cells? Embryonic cells can become all cell types of the body because they are pleuripotent. Adult stem cells are limited to differentiating into different cell types of their tissue of organ.
Embryonic stem cells can be grown relatively easily in culture. Adult stem cells are rare in mature tissues so isolation is challenging and methods to expand their numbers in cell culture have not yet been worked out.
Scientists believe that tissues derived from embryonic and adult stem cells may differ in the liklihood of being rejected after transplsntation.
5 How are stem cells harvested? 2 ways - Peripheral Blood Stem Cell Collection - The donor is seated in a chair with an IV placed into each arm. Blood is drawn out of one arm, sent to the aphaeresis machine where CD34+ stem cells are separated then the remaining blood is sent back into the other arm.
Bone Marrow Harvests-Originally collection was done by putting the donor under general anaesthetic and using a serves of needles to extract bone marrow from large bones-pelvis.
6 How are stem cells cultured in the lab? Cell culture - Scientists isolate human embryonic stem cells by transferring the inner cell mass of a blastocyst into a plastic laboratory culture dish containing a nutrient broth called a culture medium. As cells divide, they spread over the dish's surface. The inner surface of the culture dish is usually coated with mouse embryonic skin cells called a feeder layer. The cells in the feeder layer have been treated so they will not…