Autism and Stem Cells Review Paper


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Autism and Stem Cells Review Paper

  1. 1. Autism and Stem Cell Research Zoé C. Negrón Comas RISE Program Dr. Eneida Díaz December 7, 2009.
  2. 2. 2 Abstract Autism is a widely known behavioral disorder that is seen from early childhood and usually well into adulthood. Although the main cause of autism is unsure, there are many forms of experimental treatment being used today due to the rise in incidence. One of the newest theories in progress includes the use of stem cells in order to “cure” autism. Introduction Autism is a “behaviorally defined disorder” characterized by behavior that is repetitive and obsessive, lack of social skills, sensitive senses, etc. This disorder cannot, at this point, be predicted or tested for biologically, only through survey and observation. The number of children with autism has become what some would call “epidemic”, 1 in every 116 children in the United States have autism. Because of this increase in autistic tendencies, there have been more efforts in finding treatments for the disorder. There are all kinds of treatment ranging from nutritional and medical, to musical and behavioral, or combinations. But the lack of one sure cause makes it all very hard to pinpoint what is making the effect. (Braid) Usually autism is visible by age 3. But the problem with autism is that there is no unifying genetic or biological symptom or cause that one can point out. The only things that link the different autistic tendencies are behavioral. (Geschwind) Autistic children commonly suffer from: hypoperfusion and immune deregulation. Hypoperfusion to the brain, meaning that blood does not flow to the brain as it should, can cause defects in function. This can be caused by hypoxia, when the brain does not have enough oxygen to function properly, and the accumulation of neurotransmitters, etc. Immune deregulation comes from a problem in which the nervous system becomes auto-immune and the immune system itself is suppressed. Theoretically
  3. 3. 3 if both of these conditions are treated and cured simultaneously then the autistic spectrum disorder will also be cured. (Baird) Recently a new form of treatment has been proposed using stem cells. Stem cells are derived from embryos, they have been said to be a breakthrough in regenerative medicine as they can differentiate into any human cell. They have the capacity to renew themselves as well as for “multi-lineage differentiation”. These can be used in the treatment of both hypoperfusion and immune dysregulation and therefore can, in theory, cure autism. (Baird) Autism and Stem Cells The autism spectrum disorders (ASD) is composed of many different but linked disorders such as Aspeger’s syndrome and Rett’s disorder. For a long time, the world has been baffled by the causes and the origin of the neurodevelopmental syndrome called autism. There are many theories revolving around this condition, the most likely causes are said to be in brain circuitry and molecular pathways. (Eve) This is what makes autism different from many neurodegenerative disorders such as Alzheimer’s and Parkinson’s, it lacks a unifying cause that can be applied to all the cases of its kind, there is no level of the disorder that has made it possible to make connections between different manifestations of the disorder. There are many medications and treatments given to children with autism, but they are meant to target their symptoms (anxiety, depression, hyperactivity, etc.) not the disorder itself as the cause hasn’t been isolated. (Ichim) Autism is the most common in the group of ASD; it is characterized by certain abnormal behaviors within the social perspective, in the area of communication and they show repetitive and obsessive behavior. Autism can manifest itself in different degrees of
  4. 4. 4 severity, a person with autism can come to be a productive member of society and develop into self sufficient and independent adults, though this case is rare. (Ichim) One of the currently presented options for the treatment of autism is the use of stem cells. Stem cells are those that are undifferentiated, meaning they have no specialization, and have the characteristic of totipotency. Totipotency means that it has the ability to differentiate with other cells, so that if the cell is inserted into a tissue with a specific specialization it will adopt that function. Another important factor that these stem cells must have in order to serve their purpose is the ability to regenerate. There are different types of stem cells; the most commonly used at this time are the embryonic stem cells. These are found in the blastocyst. The blastocyst is a type of sphere made up of 50 to 150 cells; when it is extracted from the center of the blastocyst four or five days after the union of sperm and egg occur the cells are embryonic. These cells are characterized by rapid growth and multiplication after the 8th week which makes them perfect for stem cell treatments. (Eve) The way that stem cells and autism are associated is through hypoperfusion and immune deregulation. Hypoperfusion is the term for a decrease in blood flow to a bodily organ. When talking about autism, hypoperfusion is found in the brain. Hyperpofusion leads to hypoxia; hypoxia is the lack or deprivation of oxygen. As the brain requires about 20% of the oxygen we breathe, deprivation of oxygen presents a big problem for its functioning. Hypoperfusion adds to mental defects by induction of hypoxia and by letting neurotransmitters and metabolites accumulate. Angiogenesis makes new blood vessels from preexisting arteries; it is used for the treatment of hypoperfusion. In this case, CD34+ stem cells are administrated to increase angiogenesis, these are found in umbilical
  5. 5. 5 cord blood. Immune deregulation is what associates the nervous system and the immune system. The nervous system becomes auto-immune and renders the person immunosuppressive; meaning a lack of efficacy in the immune system. For this problem, the suggested course of action is mesenchymal stem cells. “Mesenchymal stem cells are classically defined as formative pluripotential blast cells found inter alia in bone marrow, blood, dermis and periosteum that are capable of differentiating into any of the specific types of mesenchymal or connective tissues.” (Ichim)