Novel regenerable cell culture system using signal responsive membrane substrate

近年来，利用细胞功能的生物反应器和生物人造器官得到了发展，但仍存在长期不能使用等问题。合成材料和生物材料的主要区别之一是它们的自我修复能力。当一些细胞在人造材料上死亡时，炎性物质从死亡的细胞中释放出来，并破坏邻近的活细胞，导致炎症的扩张。在本研究中，我们开发了一种快速可再生的细胞培养系统。也就是说，材料可以选择性地识别局部细胞死亡，然后主动将死亡细胞从材料表面移除，从而使产生的空隙可以通过周围细胞的生长而自愿和快速地再生。由于N-异丙基丙烯酰胺改变了其性质，将温度降至32℃以下，使细胞从N-异丙基丙烯酰胺接枝表面分离出来。在这项研究中，冠被用作识别来自死细胞的信号的传感器，而NIPAM被用作执行器。设计的聚合物是NIPAM和带有悬挂冠醚受体的苯并-18-冠-6-丙烯酰胺(BCAM)的共聚物。当冠醚捕获特定的离子时，由于客体络合物使聚合物链更亲水，使LCST向更高的温度移动。因此，当细胞死亡时，聚合物表面识别死亡细胞释放的钾离子，NIPAM水合，并选择性地分离死亡细胞。这项研究是识别细胞信号的开创性方法，在组织工程的新领域中适用于生命系统。

In recent years, bio-reactors and bio-artificial organs utilizing cellular functions have been developed, although there are still unsolved problems such as that they cannot be used for a long time period. One of the substantial differences between synthetic materials and biomaterials is their ability to self-repair. When some cells die on the artificial material, inflammatory substances are released from the dead cells and damage adjacent living cells, leading to the expansion of the inflammation. In this study, we developed a rapid regenerable cell culture system. Namely, the material can selectively recognize local cell death and subsequently remove the dead cells actively from the material surface, so that the resulting vacant spaces can be regenerated voluntarily and quickly by the growth of surrounding cells. Cells are detached from N-isopropylacrylamide (NIPAM) grafted surface by temperature decreasing below 32℃, because NIPAM changes its properties. In this study, a crown is used as a sensor that recognizes signals from dead cells, and NIPAM is used as an actuator. A designed polymer is a copolymer of NIPAM and Benzo-18-Crown-6-acrylamide (BCAm) with a pendant crown ether receptor. When the crown ether captures specific ion, the LCST shifts to higher temperature, because guest-host complex makes the polymer chain more hydrophilic. Therefore, when the cells die, the polymer surface recognizes potassium ion released from the dead cells, NIPAM hydrates, and selectively detach the dead cells. This study is a pioneering approach that recognizes cell signals and which works in living systems in the novel field of tissue engineering.