Abstract
In a current procedure for periodontal tissue regeneration, enamel matrix derivative (EMD), which is the active component, is mixed with a propylene glycol alginate (PGA) gel carrier and applied directly to the periodontal defect. Exposure of EMD to physiological conditions then causes it to precipitate. However, environmental changes during manufacture and storage may result in modifications to the conformation of the EMD proteins, and eventually premature phase separation of the gel and a loss in therapeutic effectiveness. The present work relates to efforts to improve the stability of EMD-based formulations such as Emdogain™ through the incorporation of arginine, a well-known protein stabilizer, but one that to our knowledge has not so far been considered for this purpose. Representative EMD-buffer solutions with and without arginine were analyzed by 3D-dynamic light scattering, UV-Vis spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy at different acidic pH and temperatures, T, in order to simulate the effect of pH variations and thermal stress during manufacture and storage. The results provided evidence that arginine may indeed stabilize EMD against irreversible aggregation with respect to variations in pH and T under these conditions. Moreover, stopped-flow transmittance measurements indicated arginine addition not to suppress precipitation of EMD from either the buffers or the PGA gel carrier when the pH was raised to 7, a fundamental requirement for dental applications.
Highlights
Enamel Matrix Derivative (EMD) is an acidic porcine fetal tooth extract made up of over a hundred different extra-cellular proteins (90% amelogenin, 5% ameloblastin, 5% others) [1], and is the active component of a therapeutic gel used in the regenerative treatment of periodontal disease [2,3,4,5]
We have investigated the response of EMD-buffer solutions at strongly and weakly acidic pH to heat treatments representative of those used in the manufacture of EMD-based products and, for the first time to our knowledge, the use of arginine to stabilize its behavior under these conditions
Arginine addition resulted in qualitatively similar behavior to that observed at pH 2 (Fig 4(d) and 4 (f)), consistent with the Dynamic light scattering (DLS) results, the sharp increase and subsequent decrease in absorption and scattering with increasing T shifted to around 40°C
Summary
Enamel Matrix Derivative (EMD) is an acidic porcine fetal tooth extract made up of over a hundred different extra-cellular proteins (90% amelogenin, 5% ameloblastin, 5% others) [1], and is the active component of a therapeutic gel used in the regenerative treatment of periodontal disease [2,3,4,5]. In this formulation, propylene glycol alginate (PGA) acts as a carrier for the deposition of EMD onto the affected tissue [6]. Even for amelogenin the precise links between secondary structure and aggregation remain unclear [18]
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