Shortcut to Cloned Stem Cells that Become Neurons

The findings of the research were presented at the Experimental Biology 2002 meeting in New Orleans (LA, USA).

The researchers were the first to identify the signal that instructs stem/progenitor cells to become dopamine neurons, cells that degenerate in the brains of patients with Parkinson's disease. They discovered that the primary signal is interleukin 1 (IL-1), of the class of molecules called cytokines, responsible for determining when blood stem cells differentiate into blood cells. Knowing the intention of stem cells enabled the researchers to select those cells already committed to becoming neurons and to only clone those stem cells for transplantation. Specificity is important in producing large quantities of cells that can quickly become the cells needed, and it avoids the problem of including even one cell in the cloning process not committed to becoming a neuron.

The researchers stress that the difference among various types of stem cells is not based on where they come from but how far along the lineage restriction pathway they are. There are three basic types: embryonic stem cells that can become any cell in the body but are only at the beginning of the lineage restriction pathway, stem cells for a specific organ that can become any cell in that organ, and progenitor cells committed to becoming a certain type of cell, such as a dopamine neuron. It is possible to identify progenitor cells in well-developed brains. The researchers took progenitor stem cells from the midbrain of a fetal rat, but they could also be obtained by needle biopsy from adult brains.

The researchers used their discovery to clone several generations of stem cells that when grafted into the brains of rats with a Parkinson's-like disease, developed into healthy dopamine neurons, effectively curing the severe Parkinsonian symptoms. Thus, stem cells that can become neurons have the potential to revolutionize the treatment of Alzheimer's disease and other disorders and diseases of the brain and nervous system.

"We wanted stem cells right at the point of becoming the cells we wanted and therefore unlikely to become cells we didn't want,” said Paul Carvey, Ph.D., chairman of pharmacology at Rush-Presbyterian-St. Luke's Medical Center (Chicago, IL, USA; www.rush.edu), who headed the research team. "We let the body do its own thing. We watched while it ran these stem cells down the lineage restriction pathways until the cells were almost neurons. Then we grabbed those cells, and only those cells, or our cloning activity.”




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