School of Medicine researchers has found specialized cells in the bloodstream that can form bone when located away from the actual skeleton.
Heterotopic bone formation, or the formation of bone outside of the skeleton, is a problem found in a variety of medical conditions including hip and knee replacements, brain and spinal cord trauma and end-stage aortic valve disease, where bone forms inside the heart valve.
Authors Eileen Shore and Robert Pignolo chose to study the disease fibrodysplasia ossificans progressiva, or FOP, a genetic disorder in which bone forms outside of the skeleton.
Shore, a professor of Orthopaedic Surgery and Genetics, said that in normal individuals, cells respond to injury in order to rebuild damaged tissue. However, in FOP patients, the response is different.
“The body is doing what it normally does in response to injury, except that the mutation [caused by FOP] changes cell signaling pathways,” she said. “And for reasons that we’re trying to understand better, these cells now think they are being signaled to form bone.”
According to Pignolo, a Medicine professor who specializes in geriatric medicine, the research team found that “[FOP-mutated] cells were more abundant in circulating blood in patients that were experiencing or had recently experienced a flare-up that resulted in new bone outside the skeleton.”
This observation, Pignolo added, led to experimentation and subsequent discovery of these cells in the bloodstream.
With the study’s findings, Pignolo said that the next step might be to target the problematic cells in order to keep them from forming bone at injury sites that are outside of the skeleton.
Shore also discussed the possible advancements targeting the cells would bring to treating the genetic disorder.
“If we know how to specifically target those cells in patients with heterotopic bone formation, we could deliver drugs to them or cause those cells to stop activity or die, so they don’t respond by forming bone,” Shore said.
Both Shore and Pignolo mentioned more significant long-term applications, particularly in aiding cases involving deficient bone growth or bone loss.
“If you could understand how normal bone forms outside of the skeleton … then there might be a basis for advances in learning how to put bone where it’s supposed to be,” Pignolo said.
