Periodontology Unit, Department of Clinical Research, University College London, London, United Kingdom.
Tissue Eng Part A. 2012 Jun;18(11-12):1193-202. doi: 10.1089/ten.TEA.2011.0375. Epub 2012 Mar 28.
Enamel matrix proteins (EMP) have been shown to promote regeneration of periodontal ligament and root cementum, and sometimes to enhance the differentiation of bone-forming cells in vitro and new bone growth in vivo. However, the inconsistent and unpredictable effects of EMP that have been reported for bone regeneration may be due to the highly variable composition of this heterogeneous material, which is comprised mainly of amelogenin and amelogenin-derived peptides. The present study has therefore examined the effects of naturally occurring low-molecular-weight (LMW) and high-molecular-weight (HMW) fractions of Emdogain(®) (EMD; Institut Straumann, Basel, Switzerland), a commercially available form of EMP, on osteogenic differentiation of bone precursor cells in vitro. In addition, the effects of chemically synthesized specific components of LMW and HMW-namely, the tyrosine-rich amelogenin peptide (TRAP), a specific amelogenin isoform derived by proteolytic clipping, and a leucine-rich amelogenin peptide (LRAP), an isoform derived by alternative splicing-on bone-forming cell activity were also investigated. Our findings demonstrate that while TRAP suppressed the formation of bone-like mineralized nodules, LRAP upregulated osteogenic differentiation. Furthermore, synthetically produced TRAP and its unique C-terminal 12 amino acid sequence (TCT) also suppressed bone-forming cells, whereas LRAP and its unique C-terminal 23 amino acid sequence (LCT) markedly enhanced terminal differentiation of bone-forming cells. These findings suggest that the differential effects of amelogenin-derived peptide sequences present in EMP could be of potential clinical value, with the novel bioactive TCT peptide as a useful tool for limiting pathological bone cell growth and the unique LCT sequence having therapeutic benefits in the treatment of periodontal and orthopedic diseases.
釉基质蛋白 (EMP) 已被证明可促进牙周韧带和根牙骨质的再生，并且有时可增强体外成骨细胞的分化和体内新骨的生长。然而，EMP 在骨再生方面的效果不一致且不可预测，这可能是由于这种异质材料的组成高度可变，主要由釉原蛋白和釉原蛋白衍生肽组成。因此，本研究检查了天然存在的低分子量 (LMW) 和高分子量 (HMW) 部分的 Emdogain(®) (EMD; Institut Straumann, Basel, Switzerland)，一种市售的 EMP 形式，对体外骨前体细胞成骨分化的影响。此外，还研究了 LMW 和 HMW 的化学合成特定成分的影响，即富含酪氨酸的釉原蛋白肽 (TRAP)，一种由蛋白水解剪接衍生的特定釉原蛋白同工型，以及富含亮氨酸的釉原蛋白肽 (LRAP)，一种由替代剪接衍生的同工型，对成骨细胞活性的影响。我们的研究结果表明，虽然 TRAP 抑制了骨样矿化结节的形成，但 LRAP 上调了成骨分化。此外，合成产生的 TRAP 及其独特的 C 末端 12 个氨基酸序列 (TCT) 也抑制了成骨细胞，而 LRAP 及其独特的 C 末端 23 个氨基酸序列 (LCT) 显著增强了成骨细胞的终末分化。这些发现表明，EMP 中存在的釉原蛋白衍生肽序列的差异作用可能具有潜在的临床价值，新型生物活性 TCT 肽可作为限制病理性骨细胞生长的有用工具，独特的 LCT 序列在治疗牙周和骨科疾病方面具有治疗益处。
