The world of science is developing very quickly. This can be explained by people's desire to know everything, for example, the origins of life, the structure of the human organism, the secrets of the universe, etc. Regenerative medicine, which includes stem cell research, is part of a range of scientific branches. Generally, stem cells are unique cells in the human body, which have the ability to self-renew and specialize into liver, kidney or bone marrow cells from unspecialized cells. The use of stem cells in the treatment of the most common diseases worldwide has several advantages and disadvantages. The subject of this research project is to evaluate the benefits and risks of using stem cells to cure global diseases. This is worth studying because stem cells are an integral part of the human organism and their capabilities need to be explored in order to use them in therapies for diseases such as Alzheimer's disease, Parkinson's disease, diabetes sugar, spinal cord injuries and heart disorders. It is important to know the possible risks of using stem cells, as well as their benefits. Basically, stem cells are unspecialized cells of the human body, which have a significant capacity to renew themselves and specialize in new functions. They have distinctive properties to develop into different types of cells, such as brain cells, nerve or liver cells, etc. Stem cells repair dead cells; moreover, they can divide without any limitation. Generally, there are four sources of stem cells: stem cells from the embryo; fetal stem cells; adult human stem cells; umbilical cord stem cells. Saxena (2009) points out that stem cells are divided into two categories depending on their origin. These stem cells are undifferentiated...... middle of article ......ctions. iii. How can neuronal disorders, such as Parkinson's disease, Alzheimer's disease and spinal cord injuries, be treated with stem cells and what are the fears regarding the application of this therapy to humans ? Scientists suggest that stem cells have great potential in treating neurodegenerative disorders, such as Parkinson's disease, Alzheimer's disease and spinal cord injury, but at the same time these therapies carry several risks, which can be explained by the lack of investigations in this area and require more time to carry out them. Parkinson's disease is a type of neurodegenerative disease, which is characterized by the death of special cells, which produce a chemical called dopamine. Dopamine is responsible for human movement because it transmits signals to the brain. Loss of these cells can cause symptoms such as tremors, rigidity, and inability to move (Wu 2010).