Introduction:Stem cells are cells that have the potential to develop into some or many different cell types in the body. There are two main types of stem cells, pluripotent and multipotent. The pluripotent have the ability to become any cell in the body however the multipotent cells are restricted to becoming a limited amount of cells. Embryonic stem cells:Embryonic stem cells come from developed eggs that have fertilized in a test tube also known as vitro. This happens in a clinic and then they are donated with the consent of the donor for research purposes. These are unspecialized cells that can develop into any type of cell.Uses of stem cells:Spinal cord injuries – this is the loss of muscle movement, muscle control, sensation and body system control. To treat spinal cord injuries, human umbilical cord tissue-derived stem cells and bone marrow-derived stem cells are used.Organ failure – stem cells can convert to liver tissue or heart muscle and many other organ stem cells to be used to essentially ‘replace’ the organ if it starts to weaken or failAdult stem cells:These are unspecialized cells that can develop into many (but not all) types of cells. Human stem cells can come from human embryos or from adult bone marrow but now scientists think that a tiny amount of stem cells can come from most of the different tissues in your body such as blood, brain, muscle and liver.Problems with stem cells: Many embryonic stem cells come from aborted embryos, others come from spare embryos from fertility treatment.Some people feel like the embryo can’t give permission and using it was violation of human rightsThe process of stem cells is really slow, expensive, difficult and hard to control There is some concern the embryonic stem cells might cause cancer if they are used to treat sick people, this has been seen in miceStem Cell Breakthroughs:1998- In 1998, two teams of American scientists reported that they had retrieved stem cells from human embryos for the first time. Professor James Alexander Thomson and his team at the University of Wisconsin Madison grew the first human embryonic stem cells in a laboratory dish. This allowed scientists to learn how the cells function and they found that it had the potential to turn into 220 cell types.2014- To simulate Parkinson’s Disease, researchers killed dopamine-producing neurons on one side of the rats’ brains. They converted human embryonic stem cells into dopamine-producing neurons. These were injected into the rats’ brains and evidence found that the damage was reversed.