Resumen de Effect of Enamel Matrix Derivative Liquid on Osteoblast and Periodontal Ligament Cell Proliferation and Differentiation
Richard J. Miron, Fatiha Chandad, Daniel Buser, Anton Sculean, David L. Cochran, Yufeng Zhang
Background: Enamel matrix derivatives (EMDs) have been used clinically for more than a decade for the regeneration of periodontal tissues. The aim of the present study is to analyze the effect on cell growth of EMDs in a gel carrier in comparison to EMDs in a liquid carrier. EMDs in a liquid carrier have been shown to adsorb better to bone graft materials.
Methods: Primary human osteoblasts and periodontal ligament (PDL) cells were exposed to EMDs in both gel and liquid carriers and compared for their ability to induce cell proliferation and differentiation. Alizarin red staining and real-time polymerase chain reaction for expression of genes encoding collagen 1, osteocalcin, and runt-related transcription factor 2, as well as bone morphogenetic protein 2 (BMP2), transforming growth factor (TGF)-β1, and interleukin (IL)-1β, were assessed.
Results: EMDs in both carriers significantly increased cell proliferation of both osteoblasts and PDL cells in a similar manner. Both formulations also significantly upregulated the expression of genes encoding BMP2 and TGF-β1 as well as decreased the expression of IL-1β. EMDs in the liquid carrier further retained similar differentiation potential of both osteoblasts and PDL cells by demonstrating increased collagen and osteocalcin gene expression and significantly higher alizarin red staining.
Conclusions: The results from the present study indicate that the new formulation of EMDs in a liquid carrier is equally as potent as EMDs in a gel carrier in inducing osteoblast and PDL activity. Future study combining EMDs in a liquid carrier with bone grafting materials is required to further evaluate its potential for combination therapies.
Regenerative periodontal surgery aims to predictably restore the tooth-supporting apparatus (i.e., root cementum, periodontal ligament [PDL], and bone) lost following periodontal disease or trauma.1,2 One modality that has been shown to facilitate periodontal wound healing and regeneration is the application of an enamel matrix derivative (EMD) onto debrided root surfaces and into periodontal defects.3-7 The in vitro roles of EMD have been well documented in both osteoblasts and PDL cells.8 EMD has a significant positive effect on cell adhesion, proliferation, and differentiation of many cell types by mediating cell attachment, spreading, proliferation, and survival as well as expression of transcription factors, growth factors, cytokines, extracellular matrix constituents, and other molecules involved in the regulation of bone remodeling.8 Despite the many histologic and controlled clinical studies providing evidence for periodontal regeneration,7 concerns have been expressed regarding the viscous nature of EMD in its carrier gel, which may not be sufficient to prevent flap collapse in large periodontal defects. A flap collapse may lead to a limitation of the space available for regeneration, thus limiting clinical outcomes.9,10 To overcome this potential limitation and improve the clinical results obtained with EMD, various combinations of EMD gel and different types of grafting materials have been used. Although some animal and clinical studies seem to favor the clinical combination of EMD gel plus grafting materials, others fail to demonstrate an advantage of using such a combination compared to either EMD gel alone or grafting material alone.11 Recently, quantification of proteins contained in EMD (mainly amelogenin) to adsorb to various bone grafting materials was analyzed.12 It was found that protein adsorption was superior when EMD was dissolved as a soluble liquid formulation in acetic acid compared to the commercially available EMD gel.12 Furthermore, results demonstrated that the combination of a liquid delivery system of EMD in slightly acidic conditions favored absorption of amelogenin proteins to the surface of the grafting particles as assessed by high-resolution transmission electron microscopy and protein quantification.12 Thus, the need to develop an improved carrier system for EMD with optimized protein adsorption characteristics for bone grafting material mixing may lead to improved and more stable clinical results.
Recently, a new delivery system has been explored to better optimize the physico-chemical properties of EMD in combination with bone grafting materials.12,13 This new formulation is a slightly acidic liquid formulation of EMD, dissolved with a low concentration of acetic acid and maintaining its liquid formulation.13 Combined with a bone grafting material, advantages include better surface coating and adsorption of amelogenin proteins to the bone grafting material surface and better penetration of amelogenin protein throughout certain grafting materials.13 Because no preliminary data are available testing this new formulation of EMD in a liquid carrier compared to EMD in a gel carrier, the aim of the present study is to investigate these two carrier systems with EMD on primary human osteoblasts and PDL cell behavior. Both formulations of EMD were tested for their ability to induce osteoblast and PDL cell proliferation and differentiation as assessed by real-time polymerase chain reaction (PCR) and alizarin red staining.
