Study Maps Stem Cell Bone and Cartilage Signals

Using embryonic stem cells, researchers at the Stanford University School of Medicine have mapped out the signals that direct the cells to create populations of bone, heart muscle and cartilage cells in a short period of days rather than the weeks or months presently required. The research marks a key step in creating cartilage or bone for regenerative medicine.

“Regenerative medicine relies on the ability to turn pluripotent human stem cells into specialized tissue stem cells that can engraft and function in patients, ” said Irving Weissman, M.D., the director of Stanford’s Institute for Stem Cell Biology and Regenerative Medicine, and also of its Ludwig Cancer Center. “Here we used our knowledge of the developmental biology of many other animal models to provide the positive and negative signaling factors to guide the developmental choices of these tissue and organ stem cells. Within five to nine days we can generate virtually all the pure cell populations that we need.”

The study is being published in the journal Cell. Graduate student Kyle Loh and research assistant Angela Chen, both at Stanford, share lead authorship of the study. The two learned that stem cells progressed down the developmental path through a series of choices between two possible options. They mapped out the signals that direct stem cells to become populations of any of 12 cell types, including bone, heart muscle and cartilage.

“The ability to generate pure populations of these cell types is very important for any kind of clinically important regenerative medicine, ” said Loh, “as well as to develop a basic road map of human embryonic development. Previously, making these cell types took weeks to months, primarily because it wasn’t possible to accurately control cell fate. As a result, researchers would end up with a hodgepodge of cell types.”

According to Krista Conger writing for the Stanford Medicine News Center, which reported on the study, by controlling the cell’s choices at each fork in the road, Loh and Chen were able to generate bone cell precursors that formed human bone when transplanted into laboratory mice and beating heart muscle cells. The researchers believe that the ability to quickly generate purified populations of specialized precursor cells has opened new doors to regenerative medicine.