At left, green actin fibers create architecture of the cell. At right, with cytochalasin D added, actin fibers disband and reform in the nuclei, turning the stem cells into bone cells. Photo by the University of North Carolina

CHAPEL HILL, N.C., Nov. 16 (UPI) -- Researchers at the University of North Carolina stumbled upon a method of forcing stem cells to become bone cells, finding a way to help replace bone in people who heal slowly.

Cautioning that turning stem cells into bone cells is not a solution for osteoporosis, the researchers said stem cells could help help bone fractures or hip replacement, especially for older people.


"This was not what we expected. This was not what we were trying to do in the lab," said Dr. Janet Rubin, a professor of medicine at the University of North Carolina, in a press release. "But what we've found could become an amazing way to jump-start local bone formation. However, this will not address osteoporosis, which involves bone loss throughout the skeleton."

The researchers found a protein called actin, which forms fibers in the cytoplasm portion a cell's cytoskeleton. They expected, when introducing cytochalasin D to a stem cell, that it would break up actin in the cytoskeleton, destroying its ability to become a bone cell.

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Instead, researchers found actin moved toward the nuclei of the cells, causing them to turn into osteoblasts. The researchers tested this, destroying the cells cytoskeleton but don't allow actin to enter the nucleus, cells did not become bone cells.

The researchers then tested injected the new stem cells into mice, finding that cytochalasin D induced bone growth.

"And the bone forms quickly," Rubin said. "The data and images are so clear; you don't have to be a bone biologist to see what cytochalasin D does in one week in a mouse."

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The study is published in Stem Cells.