Lin H B, Sun W, Mosher D F, García-Echeverría C, Schaufelberger K, Lelkes P I, Cooper S L
Department of Chemical Engineering, University of Wisconsin-Madison 53706.
J Biomed Mater Res. 1994 Mar;28(3):329-42. doi: 10.1002/jbm.820280307.
In an attempt to improve endothelial cell adhesion and growth on a polyurethane copolymer, cell adhesive RGD-containing peptides were grafted to the polymer backbone. Two peptide grafting reaction schemes, including one-step and two-step approaches, were developed. FTIR and amino acid analysis confirmed that coupling of the peptide to the polyurethane backbone was achieved by both the one-step and two-step methods. However, the two-step approach showed a higher peptide coupling efficiency and resulted in better control of the orientation of the grafted peptide. The two-step reaction scheme was used to prepare Gly-Arg-Gly-Asp-Ser-Tyr (GRGDSY), Gly-Arg-Gly-Asp-Val-Tyr (GRGDVY), and Gly-Arg-Gly-Glu-Ser-Tyr (GRGESY) peptide-grafted polyurethanes with two different peptide densities (100 and 250 mumol/g polymer). Dynamic contact angle measurements indicated that the surfaces of the peptide-grafted polyurethanes were more hydrophilic than the starting and carboxylated versions of the precursor polyurethane. In addition, the surface hydrophilicity of the peptide-grafted polymers increased with increasing bulk peptide density. Electron spectroscopy for chemical analysis suggested that the grafted peptide was present at the polymer-air interface, in vacuo, for the peptide-grafted polyurethanes. The surface peptide density appeared to correlate with the incorporated peptide density in the bulk. In vitro endothelial cell adhesion experiments showed that, without the presence of serum in culture medium, the GRGDSY- and GRGDVY-grafted polyurethanes dramatically enhanced cell attachment and spreading compared with the starting, carboxylated, and GRGESY-grafted polymers. Increasing the peptide density from 100 to 250 mumol/g polymer for the GRGDSY- and GRGDVY-grafted polyurethanes resulted in an increase in cell attachment. With approximately the same peptide density (100 or 250 mumol/g polymer), the GRGDVY-grafted polymers supported more adherent cells than did the GRGDSY-grafted polymers. Similar trends were observed in the in vitro endothelial cell growth studies using culture medium containing serum and endothelial cell growth supplement. The GRGDSY- and GRGDVY-grafted polyurethanes promoted more cell growth than did the starting polyurethane. However, the presence of adhesive serum proteins and growth factor diminished the differences between the cell-adhesive peptide grafted polymers and the GRGESY-grafted polymers.
为了提高内皮细胞在聚氨酯共聚物上的黏附与生长，将含细胞黏附性RGD的肽接枝到聚合物主链上。开发了两种肽接枝反应方案，包括一步法和两步法。傅里叶变换红外光谱（FTIR）和氨基酸分析证实，通过一步法和两步法均可实现肽与聚氨酯主链的偶联。然而，两步法显示出更高的肽偶联效率，并能更好地控制接枝肽的取向。采用两步反应方案制备了具有两种不同肽密度（100和250 μmol/g聚合物）的甘氨酰-精氨酰-甘氨酰-天冬氨酰-丝氨酰-酪氨酸（GRGDSY）、甘氨酰-精氨酰-甘氨酰-天冬氨酰-缬氨酰-酪氨酸（GRGDVY）和甘氨酰-精氨酰-甘氨酰-谷氨酰-丝氨酰-酪氨酸（GRGESY）肽接枝聚氨酯。动态接触角测量表明，肽接枝聚氨酯的表面比前体聚氨酯的起始版本和羧化版本更亲水。此外，肽接枝聚合物的表面亲水性随本体肽密度的增加而增加。化学分析电子能谱表明，在真空中，接枝肽存在于肽接枝聚氨酯的聚合物-空气界面处。表面肽密度似乎与本体中掺入的肽密度相关。体外内皮细胞黏附实验表明，在培养基中无血清存在的情况下，与起始、羧化和GRGESY接枝聚合物相比，GRGDSY和GRGDVY接枝聚氨酯显著增强了细胞黏附与铺展。对于GRGDSY和GRGDVY接枝聚氨酯，将肽密度从100 μmol/g聚合物增加到250 μmol/g聚合物会导致细胞黏附增加。在肽密度大致相同（100或250 μmol/g聚合物）时，GRGDVY接枝聚合物比GRGDSY接枝聚合物支持更多的黏附细胞。在使用含血清和内皮细胞生长补充剂的培养基进行的体外内皮细胞生长研究中也观察到了类似趋势。GRGDSY和GRGDVY接枝聚氨酯比起始聚氨酯促进更多的细胞生长。然而，黏附性血清蛋白和生长因子的存在减小了细胞黏附肽接枝聚合物与GRGESY接枝聚合物之间的差异。
