Potential New Sources of Stem Cells

If proven viable, two new sources of stem cells being investigated would avoid the current controversy surrounding the use of embryonic stem cells for treating disease.

Defective embryos may be one new source of stem cells, according to scientists from the Wellcome Cancer Research Institute at Cambridge University (UK). Dr. John Gurdon and colleagues discovered that defective or abnormal cloned frog embryos produced normal stem cells, which can be manipulated to form any kind of cell in the body. Many of the human embryos that result from in vitro fertilization attempts are also abnormal and are discarded. The scientists believe that some of these may produce normal stem cells.

Another potential source of stem cells under investigation is the human umbilical cord. A neuroscientist at the University of South Florida (USF, Tampa, USA), Tanja Zigova, Ph.D., has been awarded a US$1.3 million grant to study whether stem cells from human umbilical cord blood (HUCB) can treat age-related mental decline and neurodegenerative diseases. Studies suggest that HUCB may be a more readily available source of therapeutic cells for treating Parkinson's or Alzheimer's disease.

Cord blood cells include a significant number of stem cells. Researchers at the USF Center for Aging and Brain Repair have shown that these cells can be reprogrammed to become immature nerve cells. They have also demonstrated that HUCB cells transplanted into the developing brains of neonatal rats begin to look like nerve cells and express certain proteins found only in neurons and glial cells. The new USF study will use a model of aging rats to test which growth and nutritional factors best prompt malleable HUBC cells to become specific types of neurons, to determine if the age of transplant recipients affects the ability of HUBC cells to grow and differentiate, and to determine if HUCB-derived cells transplanted into the brains of aging rats can reverse or slow age-related declines in learning and memory.

"Our ultimate goal is to find out how to turn enough of them into specialized neurons that would read specific cues from the brain, migrate where we want them to go, and produce the types of neurotransmitters that must be replenished to restore nerve function,” said Dr. Zigova, principal investigator.




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