Recently, the formation of three-dimensional (3D) cell aggregates known as embryoid bodies (EBs) grown in media supplemented with HSC-specific morphogens has been utilized for the directed differentiation of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), into clinically relevant hematopoietic stem cells (HSCs). However, delivering growth factors and nutrients have become ineffective in inducing synchronous differentiation of cells due to their 3D conformation. Moreover, irregularly sized EBs often lead to the formation of necrotic cores in larger EBs, impairing differentiation. Here, we developed two gelatin microparticles (GelMPs) with different release patterns and two HSC-related growth factors conjugated to them. Slow and fast releasing GelMPs were conjugated with bone morphogenic factor-4 (BMP-4) and stem cell factor (SCF), respectively. The sequential presentation of BMP-4 and SCF in GelMPs resulted in efficient and effective hematopoietic differentiation, shown by the enhanced gene and protein expression of several mesoderm and HSC-related markers, and the increased concentration of released HSC-related cytokines. In the present study, we were able to generate CD34, CD133, and FLT3 cells with similar cellular and molecular morphology as the naïve HSCs that can produce colony units of different blood cells, in vitro.

中文翻译：

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诱导多能干细胞球体中 BMP-4 和 SCF 的逐步双释放微粒增强了向造血干细胞的分化


最近，在补充有 HSC 特异性形态发生素的培养基中生长的三维（3D）细胞聚集体（EB）的形成已被用于胚胎干细胞（ESC）和诱导多能干细胞（iPSC）的定向分化），转化为临床相关的造血干细胞（HSC）。然而，由于细胞的 3D 构象，输送生长因子和营养物质在诱导细胞同步分化方面已变得无效。此外，大小不规则的 EB 通常会导致较大 EB 中形成坏死核心，从而损害分化。在这里，我们开发了两种具有不同释放模式的明胶微粒 (GelMP) 和两种与其结合的 HSC 相关生长因子。缓慢释放和快速释放的 GelMP 分别与骨形态发生因子 4 (BMP-4) 和干细胞因子 (SCF) 结合。 BMP-4 和 SCF 在 GelMP 中的顺序呈现导致了高效且有效的造血分化，这通过几种中胚层和 HSC 相关标记物的基因和蛋白质表达增强以及释放的 HSC 相关细胞因子的浓度增加来证明。在本研究中，我们能够生成与原始 HSC 具有相似细胞和分子形态的 CD34、CD133 和 FLT3 细胞，这些细胞可以在体外产生不同血细胞的集落单位。