Singh Sonali, Awuah Dennis, Rostam Hassan M, Emes Richard D, Kandola Navrohit K, Onion David, Htwe Su Su, Rajchagool Buddharaksa, Cha Byung-Hyun, Kim Duckjin, Tighe Patrick J, Vrana Nihal E, Khademhosseini Ali, Ghaemmaghami Amir
Division of Immunology, School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
ACS Biomater Sci Eng. 2017 Jun 12;3(6):969-978. doi: 10.1021/acsbiomaterials.7b00104. Epub 2017 May 1.
Macrophages are master regulators of immune responses toward implanted biomaterials. The activation state adopted by macrophages in response to biomaterials determines their own phenotype and function as well as those of other resident and infiltrating immune and nonimmune cells in the area. A wide spectrum of macrophage activation states exists, with M1 (pro-inflammatory) and M2 (anti-inflammatory) representing either ends of the spectrum. In biomaterials research, cell-instructive surfaces that favor or induce M2 macrophages have been considered as beneficial due to the anti-inflammatory and pro-regenerative properties of these cells. In this study, we used a gelatin methacryloyl (GelMA) hydrogel platform to determine whether micropatterned surfaces can modulate the phenotype and function of human macrophages. The effect of microgrooves/ridges and micropillars on macrophage phenotype, function, and gene expression profile were assessed using conventional methods (morphology, cytokine profile, surface marker expression, phagocytosis) and gene microarrays. Our results demonstrated that micropatterns did induce distinct gene expression profiles in human macrophages cultured on microgrooves/ridges and micropillars. Significant changes were observed in genes related to primary metabolic processes such as transcription, translation, protein trafficking, DNA repair, and cell survival. However, interestingly conventional phenotyping methods, relying on surface marker expression and cytokine profile, were not able to distinguish between the different conditions, and indicated no clear shift in cell activation towards M1 or M2 phenotypes. This highlights the limitations of studying the effect of different physicochemical conditions on macrophages by solely relying on conventional markers that are primarily developed to differentiate between cytokine polarized M1 and M2 macrophages. We therefore propose the adoption of unbiased screening methods in determining macrophage responses to biomaterials. Our data clearly show that the exclusive use of conventional markers and methods for determining macrophage activation status could lead to missed opportunities for understanding and exploiting macrophage responses to biomaterials.
巨噬细胞是对植入生物材料免疫反应的主要调节者。巨噬细胞对生物材料作出反应时所采用的激活状态决定了其自身的表型和功能，以及该区域其他驻留和浸润的免疫及非免疫细胞的表型和功能。巨噬细胞存在广泛的激活状态，其中M1（促炎）和M2（抗炎）代表了该谱系的两端。在生物材料研究中，由于这些细胞具有抗炎和促进再生的特性，有利于或诱导M2巨噬细胞的细胞指导性表面被认为是有益的。在本研究中，我们使用甲基丙烯酰化明胶（GelMA）水凝胶平台来确定微图案表面是否能够调节人类巨噬细胞的表型和功能。使用传统方法（形态学、细胞因子谱、表面标志物表达、吞噬作用）和基因微阵列评估微槽/脊和微柱对巨噬细胞表型、功能和基因表达谱的影响。我们的结果表明，微图案确实在培养于微槽/脊和微柱上的人类巨噬细胞中诱导了不同的基因表达谱。在与转录、翻译、蛋白质运输、DNA修复和细胞存活等主要代谢过程相关的基因中观察到了显著变化。然而，有趣的是，依赖表面标志物表达和细胞因子谱的传统表型分析方法无法区分不同条件，并且表明细胞激活没有明显向M1或M2表型转变。这突出了仅依靠主要用于区分细胞因子极化的M1和M2巨噬细胞的传统标志物来研究不同物理化学条件对巨噬细胞影响的局限性。因此，我们建议采用无偏筛选方法来确定巨噬细胞对生物材料的反应。我们的数据清楚地表明，仅使用传统标志物和方法来确定巨噬细胞激活状态可能会导致错失理解和利用巨噬细胞对生物材料反应的机会。
