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Forming Bone from Blood
Circulating osteogenic precursor cells
form bone in vivo; © R. Pignolo/
University of Pennsylvania
The discovery that circulating blood cells can form bone outside the normal skeleton was made while studying a rare genetic disease of misplaced bone growth, fibrodysplasia ossificans progressiva, or FOP.
"Identifying circulating cells with bone-forming potential in humans has important implications for FOP, as well as more common disorders where bone is formed outside the skeleton, such as in end-stage aortic valve disease, following head and spinal cord injury, and after hip and knee replacements," says Robert J. Pignolo, Assistant Professor of Medicine at the University of Pennsylvania School of Medicine. "This type of aberrant bone growth also occurs after severe trauma, such as blast injuries suffered by Iraqi war veterans, and its study may help us understand how bone forms after the development of the skeleton has ceased, with possible applications in bone diseases where only scarce or poor quality bone forms."
The researchers analyzed blood samples from patients with FOP and unaffected individuals, isolating cells that could form bone when transplanted subcutaneously into animals. The isolated cells were characterized using surface and other markers, which identified them as being derived from bone marrow. The researchers also examined tissue from FOP patients that had formed new bone, and found that these cells had migrated into the early sites of the lesion.
"This study provides an explanation for how bone-forming cells could seed sites of injury and inflammation that subsequently develop ossifications outside the skeleton," says Frederick S. Kaplan, Professor of Orthopedic Molecular Medicine and Director of the Center for FOP & Related Disorders at Penn.
MEDICA.de; Source: University of Pennsylvania School of Medicine