Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Department of Bioscience and Engineering, College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama 337-8570, Japan.
ACS Appl Bio Mater. 2021 May 17;4(5):4598-4606. doi: 10.1021/acsabm.1c00335. Epub 2021 Apr 30.
The technique of cell patterning on a substrate is of great importance for platforms in cell-based assays. Chemical treatment of the substrate is commonly performed for cell patterning using cationic polymers, extracellular matrices, and antibodies. However, cell patterning could be easier if there is an approach to immobilize cells without treating the substrate surface. We previously reported that cell adhesion could be induced by the modification of the cellular surface with a cell-penetrating peptide (CPP)-conjugated poly(ethylene glycol)-phospholipid (CPP-PEG-lipid). This approach does not require chemical modification of the substrate surface, such as polystyrene or glass, and can be used for the cell patterning of floating cells. Here, we aimed to study the mechanism of induced cell adhesion using a representative CPP, Tat peptide (Tat-PEG-lipid). We found that cell adhesion was induced via electrostatic interactions between the Tat peptide and the substrate surface, which could be induced more efficiently by increasing the molecular weight of PEG together with CPPs but not with cationic peptides. The excluded volume effect between neighboring PEG chains could stretch the cell shape better than PEG with lower molecular weight, allowing the cell to spread firmly. In addition, Tat-PEG-lipid did not activate actin filament formation and did not influence the expression of focal adhesion kinase. Thus, the induced cell adhesion by CPP-PEG-lipid did not affect internal cell signaling.
在基于细胞的分析中，将细胞图案化到基底上的技术非常重要。通常使用阳离子聚合物、细胞外基质和抗体对基底进行化学处理以进行细胞图案化。但是，如果有一种方法可以在不处理基底表面的情况下固定细胞，那么细胞图案化可能会更容易。我们之前报道过，通过用细胞穿透肽 (CPP)-缀合的聚乙二醇-磷脂 (CPP-PEG-脂质) 修饰细胞表面，可以诱导细胞黏附。这种方法不需要对基底表面（如聚苯乙烯或玻璃）进行化学修饰，并且可用于悬浮细胞的细胞图案化。在这里，我们旨在使用代表性 CPP，即 Tat 肽 (Tat-PEG-脂质)，研究诱导细胞黏附的机制。我们发现，细胞黏附是通过 Tat 肽与基底表面之间的静电相互作用诱导的，通过增加 CPP 与 PEG 的分子量可以更有效地诱导这种相互作用，但不能与阳离子肽一起诱导。相邻 PEG 链之间的排除体积效应可以更好地拉伸细胞形状，使细胞更牢固地扩散。此外，Tat-PEG-脂质不会激活肌动蛋白丝形成，也不会影响粘着斑激酶的表达。因此，CPP-PEG-脂质诱导的细胞黏附不会影响细胞内信号转导。
