Mesenchymal Stem Cell–Induced Cranial Suture–Like Gap in Rats

Abstract

Mesenchymal stem cells are used in the reconstruction of many organs and tissues. However, there are no data regarding cranial suture regeneration using mesenchymal stem cells. Because cranial sutures are important for cranial bone growth, the authors examined whether mesenchymal stem cells could aid with suture reformation in adolescent rats. Mesenchymal stem cells were isolated from bone marrow of rat femora. Twenty 4-week-old Fischer 344 male rats received sagittal suture and bone defects with a diameter of 6.0 mm, and mesenchymal stem cells were grafted with membranes. Twenty control rats underwent empty membrane transplantation. The mesenchymal stem cell and control groups were killed at 4, 8, 16, and 24 weeks after surgery. The parietal bones, including the sagittal suture, were observed under a light microscope. Bone structures were measured on digitized photomicrographs captured in a computer. For each sample, bone and suture regeneration were observed by dorsoventral cephalograms. In 4- and 8-week control and mesenchymal stem cell groups, a small volume of new bone formation was observed. In the 16- and 24-week mesenchymal stem cell groups, a large amount of new bone formation and a suture-like gap were identified. In contrast, only a small volume of new bone formation along with craniosynostosis was detected in the 24-week control group. These results suggest that mesenchymal stem cell grafting may be a novel option for cranioplasty, not only repairing bone tissue but also resulting in suture-like gap formation, which may advance cranial bone growth.