Experimental Study on Healing of Periosteal Defects in Mouse Cranium

Abstract

Surgery on tumorous bone often requires resection of the corresponding normal tissues including the periosteum, particularly for malignancies. The periosteum supplies nutrition to the bone and is an essential tissue as a recipient bed for mucosa grafting. The conditions necessary for survival of a mucosa graft include a well-vascularized host bed and rapid serum imbibition occurring immediately after grafting. This study was designed to reveal the regenerative process of the periosteum. Forty mice were used. A defect of the periosteum was surgically created following the elevation of the skin flap on the cranium of mice under general anesthesia. The histological findings of elastic as well as collagen fibers and the immunohistochemical expression of parathyroid hormone (PTH)/PTH-related peptide (PTH/PTHrP) receptor and proliferating cell nuclear antigen (PCNA) at the postoperative intervals were investigated. At 7 days postoperatively, the periosteal defect was occupied by a periosteum-like tissue (PLT) composed of two layers (a collagen layer and an elastic layer), which was different from the normal periosteum. A positive reaction to PTH/PTHrP receptor was seen in the PLT, similar to that shown for the normal periosteum. The immunoreaction of PCNA as well as PTH/PTHrP receptor reached its peak at 5 or 7 days and gradually decreased till 84 days postoperatively. At 84 days postoperatively, the PLT was remodeled to have almost the same features as the normal periosteum composed of a collagen layer. These results suggest that an adequate healing period is needed for the periosteal defect site where the transplanted bone will be subjected to mucosa grafting.