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New stem cell growth strategy could yield better way to treat brain lesions

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Many medical experts have long believed that neural stem cells (NSCs) have great potential for treating neurological diseases. However, the problem is that just a small number of NSCs can be transplanted into the brain, yielding relatively low levels of new cell growth and, thus, a limited effect. “We wanted to investigate whether using a specific population of neural cells would help increase the number of mature brain cells that the stem cell graft yields,” Dr. Wolfe explained.

The team began by harvesting NSCs from the brains of baby mice and used a process known as fluorescence activated cell sorting to identify cells with markers for CD15, a type of carbohydrate found on a cell’s surface that plays an important role in cell migration, adhesion and in the growth factor signaling involved in cell maintenance and differentiation.

Cells sorting allowed the scientists to achieve a population of cells in which 98 percent were CD15-positive. This process resulted in six times more CD15-positive cells than when cell sorting is not used. These cells were then differentiated in the lab into neurons, astrocytes and oligodendrocytes, which are types of cells found in the central nervous system (the brain and spinal cord). The team next tested both sorted and non-sorted neural cells by injecting them into baby mice. One week later, a time when the brain is still growing, they found that cells from both groups had populated the animals’ brains at a similar level.

“However, in the adult brain the survival of donor cells was significantly higher in the CD15-positive grafts than it was in the unsorted group,” Dr. Wolfe said. In addition, the engrafted stem cells had differentiated into all three types of neural cells with the CD15-positive ones showing a significant tendency to differentiate into oligodendrocytes. This type of cell plays a vital role in protecting neurons.

“This strategy may allow for better delivery of therapeutic cells to the brain,” said Anthony Atala, MD, editor of STEM CELLS Translational Medicineand director of the Wake Forest Institute for Regenerative Medicine. “The fact that the CD15-positive cells show a significant increase in oligodendrocytic differentiation suggests that they may be particularly useful for treating diseases involving white matter lesions.”