The effect of the addition of a polyglutamate motif to RGD on peptide tethering to hydroxyapatite and the promotion of mesenchymal stem cell adhesion
The effect of the addition of a polyglutamate motif to RGD on peptide tethering to hydroxyapatite and the promotion of mesenchymal stem cell adhesion
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DOI：
10.1016/j.biomaterials.2005.05.006
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发表时间：
2005-12-01
期刊：
影响因子：
14
通讯作者：
Bellis, SL
中科院分区：
文献类型：
--
作者：
Sawyer, AA;Weeks, DM;Bellis, SL
RGD 肽模仿内源性骨结合蛋白，合成时具有多酸氨基酸结构域，以便将肽以离子方式束缚至骨样合成生物材料，包括羟基磷灰石 (HA)。然而，尚未对未修饰的 RGD 与多酸缀合的 RGD 进行直接比较，因此尚未确定酸性结构域的益处。我们评估了带有和不带有附加聚谷氨酸序列 (E-7) 的 RGD 肽的肽/HA 键，并检查了间充质干细胞 (MSC) 粘附和形态，因为它们受到缀合肽的影响。我们发现，在所有测试的涂层浓度下，与 HA 结合的 E(7)RGD 明显多于 RGD，而且，即使在无血清介质中长时间洗涤后，更多的 E(7)RGD 仍保留在 HA 表面上。与体外结果一致，体内植入24小时的HA上保留的E(7)RGD水平高于RGD，表明多酸结构域提高了肽结合效率。在几种肽浓度下，与 RGD 表面相比，E(7)RGD 增加了细胞粘附，从而确定了 E-7 修饰的生物学益处。此外，与单独涂层相比，用低密度 E(7)RGD (1-10 μg/ml) 和血清 (FBS) 依次预涂 HA 可刺激细胞粘附和扩散，表明离子键允许血清蛋白潜在吸附到未占据的位点，这对于体内骨形成可能很重要。总的来说，这些结果表明，通过聚谷氨酸结构域将肽与 HA 结合是改善肽/HA 键以及增强 MSC 粘附的有效方法。 (c) 2005 Elsevier Ltd. 保留所有权利。
Mimicking endogenous bone-binding proteins, RGD peptides have been synthesized with polyacidic amino acid domains in order to ionically tether the peptides to bone-like synthetic biomaterials, including hydroxyapatite (HA). However, a direct comparison of unmodified RGD with polyacidic-conjugated RGD has not been performed, and thus a benefit for the acidic domain has not been established. We evaluated the peptide/HA bond of RGD peptides with and without an attached polyglutamate sequence (E-7) as well as examined mesenchymal stem cell (MSC) adhesion and morphology as they were affected by the conjugated peptide. We found that significantly more E(7)RGD was bound to HA than RGD at all coating concentrations tested, and moreover, more E(7)RGD was retained on the HA surface even after extended washing in serum-free media. Consistent with in vitro results, higher levels of E(7)RGD than RGD remained on HA that had been implanted in vivo for 24h, indicating that the polyacidic domain improved peptide-binding efficiency. At several peptide concentrations, E(7)RGD increased cell adhesion compared to RGD surfaces, establishing a biological benefit for the E-7 modification. In addition, HA pre-coated sequentially with low-density E(7)RGD (1-10 mu g/ml) and serum (FBS) stimulated cell adhesion and spreading, compared to either coating alone, suggesting that an ionic linkage allows for the potential adsorption of serum proteins to unoccupied sites, which may be important for bone formation in vivo. Collectively, these results suggest that tethering peptides to HA via a polyglutamate domain is an effective method for improving the peptide/HA bond, as well as for enhancing MSC adhesion. (c) 2005 Elsevier Ltd. All rights reserved.