Phorbol myristate acetate (PMA)-differentiated THP-1 cells are routinely used in lieu of primary macrophages to study macrophage polarization during host-pathogen interactions and disease progression. The phenotypes of THP-1 macrophages are influenced by the level and duration of PMA stimulation and possibly also by the presence of adhesion factors. Here, we use self-organizing maps (SOMs) of single-cell Raman spectra to probe the effects of PMA stimulation conditions and adhesion factors on THP-1 cell differentiation. Raman spectra encoding for biochemical composition were acquired from individual cells on substrates coated with fibronectin or poly-l-lysine before and after stimulation with 20 or 200 nM PMA for two different time intervals. SOMs constructed from these spectra showed the extent of spectral dissimilarity between different chronological cell populations. For all conditions, the SOMs indicated that the spectra acquired from cells after three-day treatment had diverged from those of untreated cells. The SOMs also showed that the higher PMA concentration produced both fully and partially differentiated cells for both adhesion factors after three days, whereas the outcome of stimulation for three days with the lower PMA concentration depended on the adhesion factor. On poly-l-lysine, treatment with 20 nM PMA for three days induced an intermediate stage of differentiation, but the same treatment produced partially and fully differentiated cells when applied to THP-1 cells on fibronectin. These results are consistent with the modulation of the transition of THP-1 monocytes into macrophage-like cells by integrin-binding interactions. Furthermore, differences in culture and stimulation conditions may confound comparison of results from separate studies.

中文翻译：

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使用单细胞拉曼光谱的自组织图探索单核细胞系的成熟。


通常用佛波醇肉豆蔻酸酯 (PMA) 分化的 THP-1 细胞代替原代巨噬细胞来研究宿主-病原体相互作用和疾病进展期间的巨噬细胞极化。 THP-1 巨噬细胞的表型受到 PMA 刺激的水平和持续时间的影响，也可能受到粘附因子存在的影响。在这里，我们使用单细胞拉曼光谱的自组织图 (SOM) 来探讨 PMA 刺激条件和粘附因子对 THP-1 细胞分化的影响。在用 20 或 200 nM PMA 刺激两个不同时间间隔之前和之后，从涂有纤连蛋白或聚-L-赖氨酸的基底上的单个细胞获取编码生化成分的拉曼光谱。从这些光谱构建的 SOM 显示了不同时间顺序细胞群之间光谱差异的程度。对于所有条件，SOM 表明处理三天后从细胞获得的光谱与未经处理的细胞的光谱有所不同。 SOM 还表明，三天后，较高的 PMA 浓度可针对两种粘附因子产生完全和部分分化的细胞，而较低 PMA 浓度刺激三天的结果取决于粘附因子。对于聚-L-赖氨酸，用 20 nM PMA 处理三天诱导分化的中间阶段，但当将相同的处理应用于纤连蛋白上的 THP-1 细胞时，产生部分和完全分化的细胞。这些结果与通过整合素结合相互作用调节 THP-1 单核细胞向巨噬细胞样细胞的转变是一致的。 此外，培养和刺激条件的差异可能会混淆单独研究结果的比较。