Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332-0363, USA.
Clin Oral Implants Res. 2011 Aug;22(8):865-72. doi: 10.1111/j.1600-0501.2010.02074.x. Epub 2011 Jan 18.
Functionalizing surfaces with specific peptides may aid osteointegration of orthopedic implants by favoring attachment of osteoprogenitor cells and promoting osteoblastic differentiation. This study addressed the hypothesis that implant surfaces functionalized with peptides targeting multiple ligands will enhance osteoblast attachment and/or differentiation. To test this hypothesis, we used titanium (Ti) surfaces coated with poly-l-lysine-grafted polyethylene glycol (PLL-g-PEG) and functionalized with two peptides found in extracellular matrix proteins, arginine-glycine-aspartic acid (RGD) and lysine-arginine-serine-arginine (KRSR), which have been shown to increase osteoblast attachment. KSSR, which does not promote osteoblast attachment, was used as a control.
Sandblasted acid-etched titanium surfaces were coated with PLL-g-PEG functionalized with varying combinations of RGD and KRSR, as well as KSSR. Effects of these surfaces on osteoblasts were assessed by measuring cell number, alkaline phosphatase-specific activity, and levels of osteocalcin, transforming growth factor beta-1 (TGF-β1), and PGE(2).
RGD increased cell number, but decreased markers for osteoblast differentiation. KRSR alone had no effect on cell number, but decreased levels of TGF-β1 and PGE(2). KRSR and RGD/KRSR coatings inhibited osteoblast differentiation vs. PLL-g-PEG. KSSR decreased cell number and increased osteoblast differentiation, indicated by increased levels of osteocalcin and PGE(2).
The RGD and KRSR functionalized surfaces supported attachment but did not enhance osteoblast differentiation, whereas KSSR increased differentiation. RGD decreased this effect, suggesting that multifunctional peptide surfaces can be designed that improve peri-implant healing by optimizing attachment and proliferation as well as differentiation of osteoblasts, but peptide combination, dose and presentation are critical variables.
通过促进成骨细胞附着和促进成骨细胞分化，用特定的肽功能化表面可能有助于骨科植入物的骨整合。本研究假设用针对多种配体的肽功能化的植入物表面将增强成骨细胞的附着和/或分化。为了验证这一假设，我们使用了涂有聚赖氨酸接枝聚乙二醇（PLL-g-PEG）的钛（Ti）表面，并对其进行了功能化，使用了两种在细胞外基质蛋白中发现的肽，精氨酸-甘氨酸-天冬氨酸（RGD）和赖氨酸-精氨酸-丝氨酸-精氨酸（KRSR），这两种肽已被证明能增加成骨细胞的附着。不促进成骨细胞附着的 KSSR 被用作对照。
喷砂酸蚀钛表面涂有 PLL-g-PEG，并用不同组合的 RGD 和 KRSR 以及 KSSR 进行功能化。通过测量细胞数量、碱性磷酸酶特异性活性以及骨钙素、转化生长因子-β1（TGF-β1）和 PGE（2）的水平来评估这些表面对成骨细胞的影响。
RGD 增加了细胞数量，但降低了成骨细胞分化的标志物。单独的 KRSR 对细胞数量没有影响，但降低了 TGF-β1 和 PGE（2）的水平。KRSR 和 RGD/KRSR 涂层抑制了成骨细胞分化，与 PLL-g-PEG 相比。KSSR 降低了细胞数量并增加了成骨细胞分化，表现为骨钙素和 PGE（2）水平升高。
RGD 和 KRSR 功能化表面支持附着，但不能增强成骨细胞分化，而 KSSR 增加了分化。RGD 降低了这种效应，这表明可以设计多功能肽表面，通过优化成骨细胞的附着和增殖以及分化来改善种植体周围的愈合，但肽的组合、剂量和呈现是关键变量。
