Abstract
BACKGROUND: Polymorphonuclear leukocyte (PMN) is the predominant innate immune cell type activated in acute inflammation. The aim of this study is to determine the impact of enamel matrix derivative (EMD) on superoxide (O(2)(-)) generation, chemotaxis, and matrix metalloproteinase-8 (MMP-8) secretion by PMN in vitro to better understand the role of EMD in surgical wound healing. METHODS: PMNs were isolated from healthy volunteers (n = 14). O(2)(-) generation was measured using a cytochrome c reduction assay. Chemotaxis was measured in a modified Boyden chamber. MMP-8 secretion was analyzed by Western blotting. A relative density method was used to determine the percentage of MMP-8 released from the PMNs in relation to the total cellular MMP-8 content. RESULTS: O(2)(-) generation was significantly elevated when PMNs were stimulated with EMD (200 μg/mL) (P <0.01). Secondary stimulation of PMNs with 1 μM N-formyl-methionyl-leucyl-phenylalanine (fMLP) triggered earlier and more sustained O(2)(-) generation with EMD. EMD significantly increased PMN chemotactic activity (P <0.05). Combined stimulation with EMD plus fMLP resulted in significantly higher chemotaxis compared to fMLP alone (P <0.05). Conversely, EMD did not induce MMP-8 secretion from PMNs. MMP-8 secretion by PMNs in response to fMLP or serum-opsonized zymosan stimulation was significantly inhibited by EMD (P <0.05). CONCLUSIONS: EMD has specific, differential actions on PMNs that suggest potential for enhancement of wound healing, bacterial and tissue debris clearance (O(2)(-) generation and chemotaxis), and suppression of tissue damage and degradation (MMP-8 ). Together, the data suggest that EMD enhances wound healing and reduces inflammation.