Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku, Tokyo 162-8666, Japan.
Biomacromolecules. 2012 Jan 9;13(1):253-60. doi: 10.1021/bm201545u. Epub 2011 Dec 6.
For preparing cell sheets effectively for cell sheet-based regenerative medicine, cell-adhesion strength to thermoresponsive cell culture surfaces need to be controlled precisely. To design new thermoresponsive surfaces via a terminal modification method, thermoresponsive polymer brush surfaces were fabricated through the surface-initiated reversible addition-fragmentation chain transfer (RAFT) radical polymerization of N-isopropylacrylamide (IPAAm) on glass substrates. The RAFT-mediated grafting method gave dithiobenzoate (DTB) groups to grafted PIPAAm termini, which can be converted to various functional groups. In this study, the terminal carboxylation of PIPAAm chains provided high cell adhesive property to thermoresponsive surfaces. Although cell adhesion is generally promoted by a decrease in the grafted PIPAAm amount, the decrease also decelerated thermally-induced cell detachment, whereas the influence of terminal modification was negligible on the cell detachment. Consequently, the terminally modified PIPAAm brush surfaces allowed smooth muscle cells (SMCs) to simultaneously adhere strongly and detach themselves rapidly. In this study, SMCs were unable to reach a confluent monolayer on as-prepared PIPAAm brush surfaces (grafted amount: 0.41 μg/cm(2)) without terminal carboxylation due to their insufficient cell-adhesion strength. On the other hand, though a decrease in the PIPAAm amount allowed SMCs to form a confluent cell monolayer on the PIPAAm brush surface, the SMCs were unable to be harvested as a monolithic cell sheet by low-temperature culture at 20 °C. Because of their unique property, only terminal-carboxylated PIPAAm brush surfaces achieved rapid harvesting of complete cell sheets by low-temperature culturing.
为了有效地制备细胞片用于基于细胞片的再生医学,需要精确控制细胞对温敏细胞培养表面的粘附强度。为了通过末端修饰方法设计新的温敏表面,通过在玻璃基底上进行 N-异丙基丙烯酰胺(IPAAm)的表面引发可逆加成-断裂链转移(RAFT)自由基聚合,制备了温敏聚合物刷表面。RAFT 介导的接枝方法将二硫代苯甲酸酯(DTB)基团接枝到接枝的 PIPAAm 末端,该基团可以转化为各种官能团。在这项研究中,PIPAAm 链的末端羧化提供了对温敏表面的高细胞粘附性。虽然细胞粘附通常通过降低接枝的 PIPAAm 量来促进,但这种降低也会减缓热诱导的细胞脱落,而末端修饰的影响对细胞脱落可忽略不计。因此,末端修饰的 PIPAAm 刷表面允许平滑肌细胞(SMC)同时强烈地粘附并快速地自身脱落。在这项研究中,由于其细胞粘附强度不足,未经末端羧化的 PIPAAm 刷表面(接枝量:0.41μg/cm(2))上的平滑肌细胞无法形成致密的单层。另一方面,尽管 PIPAAm 量的减少允许 SMC 在 PIPAAm 刷表面上形成致密的细胞单层,但SMC 无法通过 20°C 的低温培养作为整体细胞片收获。由于其独特的性质,只有末端羧化的 PIPAAm 刷表面通过低温培养才能快速收获完整的细胞片。
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