Researchers at the Stanford School of Medicine have isolated stem cells in mice that are able to differentiate into bone, cartilage, or even stroma (the spongy tissue at the center of bones that helps hematopoietic stem cells turn into blood and immune cells).
In addition, the researchers have charted the chemical signals that can create skeletal stem cells and steer their development into each of these specific tissues. The discovery sets the stage for a wide range of potential therapies for skeletal disorders such as bone fractures, brittle bones, osteosarcoma or damaged cartilage.
Through focused effort, researchers were able to determine that a single type of cell, skeletal stem cells, are able to change into progenitor cells, and thus eventually different types of skeletal tissue. “Mapping the tree led to an in-depth understanding of all the genetic switches that have to be flipped in order to give rise to more specific progenitors and eventually highly specialized cells,” said postdoctoral scholar Charles Chan, PhD. With that information, the researchers were able to find factors that could guide the development of skeletal stem cells into bone, cartilage or stromal cells.
Taking the research one step further, they were able to learn a method for creating these special skeletal stem cells from fat or muscle cells. This allows for an impressive array of treatment options for patients who do not have extra skeletal stem cells due to injury or old age. Longaker says “Right now, if you have lost a significant portion of your leg or jaw bones, you have to borrow from Peter to pay Paul in that you have to cut another bone like the fibula into the shape you need, move it and attach it to the blood supply. But if your existing bone is not available or not sufficient, using this research you might be able to put some of your own fat into a biomimetic scaffold, let it grow into the bone you want in a muscle or fat pocket, and then move that new bone to where it’s needed.”
The next step for these researchers is testing to see if these results hold true in the human body. The Stanford scientists are confident in the ability to translate this mice research to human application. “In this research we now have a Rosetta stone that should help find the human skeletal stem cells and decode the chemical language they use to steer their development,” Chan said. “The pathways in humans should be very similar and share many of the major genes used in the mouse skeletal system.”