The immune system responds immediately to tissue trauma and to biomaterial implants under the participation of M1/M2 macrophages polarization. The surface properties of biomaterials can significantly influence the tissue repair progress through modulating the macrophage functions. In this study, the surface of poly(propylene fumarate) polyurethane films (PPFU) is grafted with a same density of enantiomeric poly-l-lysine (PPFU-g-PLL) and poly-d-lysine (PPFU-g-PDL), leading to a similar level of enhanced surface wettability for the PPFU-g-PLL and PPFU-g-PDL. The polylysine-grafted PPFU can restrict the M1 polarization, whereas promote M2 polarization of macrophages in vitro, judging from the secretion of cytokines and expression of key M1 and M2 related genes. Comparatively, the PPFU-g-PDL has a stronger effect in inducing M2 polarization in vivo, resulting in a thinner fibrous capsule surrounding the implant biomaterials. The CD44 and integrins of macrophages participate in the polarization process probably by activating focal adhesion kinase (FAK) and rho-associated protein kinase (ROCK), and downstream PI3K/Akt1/mTOR signal axis to up regulate M2 related gene expression. This study confirms for the first time that polylysine coating is an effective method to regulate the immune response of biomaterials, and the polylysine-modified thermoplastic PPFU with the advantage to promote M2 polarization may be applied widely in regenerative medicine.

免疫系统在M1 / M2巨噬细胞极化的参与下立即对组织创伤和生物材料植入物做出反应。生物材料的表面特性可通过调节巨噬细胞功能来显着影响组织修复的进程。在这项研究中，富马酸丙二醇酯聚氨酯薄膜（PPFU）的表面接枝了相同密度的对映体聚1-赖氨酸（PPFU-g-PLL）和聚d-赖氨酸（PPFU-g-PDL） ，导致PPFU-g-PLL和PPFU-g-PDL的表面润湿性达到相似的水平。聚赖氨酸接枝的PPFU可以限制M1极化，而在体外促进巨噬细胞的M2极化从细胞因子的分泌以及关键的M1和M2相关基因的表达来判断。相比之下，PPFU-g-PDL在体内诱导M2极化方面具有更强的作用，从而使植入的生物材料周围的纤维囊更薄。CD44和巨噬细胞整合素可能通过激活粘着斑激酶（FAK）和rho相关蛋白激酶（ROCK）以及下游PI3K / Akt1 / mTOR信号轴来上调M2相关基因的表达，从而参与极化过程。这项研究首次证实，聚赖氨酸涂层是调节生物材料免疫反应的有效方法，聚赖氨酸改性的热塑性PPFU具有促进M2极化的优势，可广泛用于再生医学。