Sawyer A A, Hennessy K M, Bellis S L
Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Biomaterials. 2005 May;26(13):1467-75. doi: 10.1016/j.biomaterials.2004.05.008.
The successful development of biomaterials must take into consideration how those surfaces will interact with in vivo processes such as adsorption of endogenous proteins. In this study, we examined whether modifying highly adsorbent materials like hydroxyapatite (HA) with RGD peptides would improve mesenchymal stem cell (MSC) adhesion. We found that RGD, alone, was not sufficient to promote full cell spreading. However, given that RGD-modified HA will likely adsorb osteogenic serum proteins in vivo, we evaluated MSC behavior on HA pre-coated with RGD, then over-coated with serum (RGD/FBS). Interestingly, RGD/FBS coatings additively stimulated MSC attachment and spreading compared to either coating alone, but only at low RGD coating concentrations. High RGD concentrations inhibited cell attachment, and completely eliminated cell spreading on RGD/FBS surfaces. To better understand the mechanism by which RGD and adsorbed serum proteins interactively regulate cell behavior, we monitored the deposition of fibronectin (FN) from serum onto HA pre-coated with increasing RGD concentrations. These studies showed that high RGD concentrations did not inhibit FN adsorption, therefore cell spreading is attenuated by mechanisms other than lack of FN availability. Collectively, our results suggest a potential therapeutic benefit for functionalizing HA with RGD, however such a benefit will likely depend upon the RGD density.
生物材料的成功研发必须考虑这些材料表面将如何与体内过程相互作用，如内源性蛋白质的吸附。在本研究中，我们检测了用RGD肽修饰高吸附性材料（如羟基磷灰石（HA））是否会改善间充质干细胞（MSC）的黏附。我们发现，单独的RGD不足以促进细胞完全铺展。然而，鉴于RGD修饰的HA在体内可能会吸附成骨血清蛋白，我们评估了MSC在预先用RGD包被、然后再用血清包被（RGD/胎牛血清（FBS））的HA上的行为。有趣的是，与单独的任何一种包被相比，RGD/FBS包被可累加地刺激MSC的附着和铺展，但仅在低RGD包被浓度下如此。高RGD浓度会抑制细胞附着，并完全消除细胞在RGD/FBS表面的铺展。为了更好地理解RGD和吸附的血清蛋白如何相互作用调节细胞行为的机制，我们监测了血清中纤连蛋白（FN）在预先用递增浓度RGD包被的HA上的沉积。这些研究表明，高RGD浓度不会抑制FN的吸附，因此细胞铺展减弱是由缺乏FN可用性以外的机制所致。总体而言，我们的结果表明用RGD对HA进行功能化具有潜在的治疗益处，然而这种益处可能取决于RGD密度。
