Decoupling Hydrogel Stiffness and Diffusivity for Hematopoietic Stem Cell Culture and Differentiation

项目摘要 骨髓中的造血干细胞（HSC）通过粘附到细胞膜上来接收机械信号。 细胞外基质和来自细胞因子扩散通过细胞外基质的化学信号。这两 信号传导方法影响HSC的存活、增殖和分化，对HSC的增殖和分化具有重要的长期影响。 免疫系统和身体维持体内平衡的能力。虽然使用合成水凝胶的体外研究 作为人工基质，对HSC的行为、刚度和溶质的环境控制有了新的认识 运输在合成水凝胶中高度相关，因此HSC对这些物质的反应背后的机制 环境仍然不确定。由此产生的水凝胶物理性质的不确定性和有限控制 这些特性可以解释为什么没有建立体外HSC扩增的稳健方法。 因此，本文提出的研究将填补水凝胶设计能力的关键空白，并将新的 HSC体外培养的相关知识。首先，我们将创建一个45个独特的水凝胶配方库， 同时操纵三个结构水凝胶合成参数， 预测在刚度和溶质传输中产生稳健的独立变化。第二，我们将培养HSC 在具有独立调节的刚度的水凝胶制剂的较小的九制剂方阵中， 溶质转运谱，以分离两种物理水凝胶性质如何影响HSC存活，增殖， 和差异化。这些研究将为HSC与它们的物理相互作用提供基本的见解。 环境和鉴定用于体外HSC培养的物理优化条件。

PROJECT ABSTRACT Hematopoietic stem cells (HSCs) in the bone marrow receive mechanical signals via adhesions to the extracellular matrix and chemical signals from cytokines diffusing through the extracellular matrix. These two signaling methods influence HSC survival, proliferation, and differentiation, with critical long-term effects on the immune system and the body’s ability to maintain homeostasis. While in vitro studies using synthetic hydrogels as artificial matrices have led to new insights on environmental control of HSC behavior, stiffness and solute transport are highly correlated in synthetic hydrogels, so the mechanisms behind HSC responses to these environments remain uncertain. The resulting uncertainty and limited control of hydrogel physical properties may explain why robust methods for in vitro HSC expansion have not been established. Therefore, the studies proposed here will fill a critical gap in hydrogel design capabilities and apply that new knowledge to in vitro HSC culture. First, we will create a library of forty-five unique hydrogel formulations by simultaneously manipulating three structural hydrogel synthesis parameters that our fundamental models have predicted to create robust, independent variations in stiffness and solute transport. Second, we will culture HSCs in a smaller, nine-formulation square matrix of hydrogel formulations with independently tuned stiffnesses and solute transport profiles to decouple how the two physical hydrogel properties affect HSC survival, proliferation, and differentiation. These studies will provide fundamental insight into HSC interactions with their physical environment and identify physically optimized conditions for in vitro HSC culture.