Effects of application of hyaluronan to rat calvarial defects on bone formation

Abstract

Hyaluronan (HA) is a component of the extracellular matrix that is associated with inflammatory reactions. Application of HA can effect the wound healing of soft tissue. However the effect of HA on bone metabolism is unclear. The purpose of this study was to evaluate the usefulness of application of HA to cranial bone defects on bone formation in rats. We investigated the effect of application of different molecular weights (9×10⁵,25×10⁵) of HA to calvarial bone defects in the rat. The control bone defects were filled with PBS. The experimental sites were examined by standardized radiological analysis after surgery. Rats were sacrificed 1, 2, or 3 weeks after surgery, and the cranial tissue was removed and the experimental site was sectioned for histological study. Paraffin sections were stained with hematoxylin and eosin, and for tartrate-resistant acid phosphatase and alkaline phosphatase. The area of the newly formed bone was measured under a microscope,and the effect of gelatin as a scaffold for HA delivery was assessed at the same time. At 3 weeks after surgery there was significantly more new bone formation in the bone defect in the HA groups than in the control group. The localization of TRAP positive site was seen most strongly on the bone margin one week after surgery. There was less new bone formation in the HA with gelatin group than in the HA without gelatin group. There were no significant differences between the concentrations of HA. The gelatin as a scaffold for HA inhibited bone formation. HA enhances cranial bone formation in rats, and HA may be useful for alveolar bone regeneration.
Nihon Shishubyo Gakkai Kaishi (J Jpn Periodontol) 49 : 305-315, 2007.