Earliest Mineral and Matrix Changes in Force-Induced Musculoskeletal Disease as Revealed by Raman Microspectroscopic Imaging

Craniosynostosis, premature fusion of the skull bones at the sutures, is the second most common human birth defect in the skull. Raman microspectroscopy was used to examine the composition, relative amounts, and locations of the mineral and matrix produced in mouse skulls undergoing force-induced craniosynostosis. Raman imaging revealed decreased relative mineral content in skulls undergoing craniosynostosis compared with unloaded specimens. Introduction: Raman microspectroscopy, a nondestructive vibrational spectroscopic technique, was used to examine the composition, relative amounts, and locations of the mineral and matrix produced in mouse skulls undergoing force-induced craniosynostosis. Craniosynostosis, premature fusion of the skull bones at the sutures, is the second most common birth defect in the face and skull. The calvaria, or flat bones that comprise the top of the skull, are most often affected, and craniosynostosis is a feature of over 100 human syndromes and conditions. Materials and Methods: Raman images of the suture, the tips immediately adjacent to the suture (osteogenic fronts), and mature parietal bones of loaded and unloaded calvaria were acquired. Images were acquired at 2.6 x 2.6 mu m spatial resolution and ranged in a field of view from 180 x 210 mu m to 180 x 325 mu m. Results and Conclusions: This study found that osteogenic fronts subjected to uniaxial compression had decreased relative mineral content compared with unloaded osteogenic fronts, presumably because of new and incomplete mineral deposition. Increased matrix production in osteogenic fronts undergoing craniosynostosis was observed. Understanding how force affects the composition, relative amounts, and location of the mineral and matrix provides insight into musculoskeletal disease in general and craniosynostosis in particular. This is the first report in which Raman microspectroscopy was used to study musculoskeletal disease. These data show how Raman microspectroscopy can be used to study subtle changes that occur in disease.