Stem cells reside in complex three-dimensional (3D) environments within the body that change with time, promoting various cellular functions and processes such as migration and differentiation. These complex changes in the surrounding environment dictate cell fate yet, until recently, have been challenging to mimic within cell culture systems. Hydrogel-based biomaterials are well suited to mimic aspects of these in vivo environments, owing to their high water content, soft tissue-like elasticity, and often-tunable biochemical content. Further, hydrogels can be engineered to achieve changes in matrix properties over time to better mimic dynamic native microenvironments for probing and directing stem cell function and fate. This review will focus on techniques to form hydrogel-based biomaterials and modify their properties in time during cell culture using select addition reactions, cleavage reactions, or non-covalent interactions. Recent applications of these techniques for the culture of stem cells in four dimensions (i.e., in three dimensions with changes over time) also will be discussed for studying essential stem cell processes.

中文翻译：

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用于 4D 干细胞培养的生物材料。


干细胞存在于体内复杂的三维 (3D) 环境中，该环境随时间而变化，促进各种细胞功能和过程，例如迁移和分化。周围环境的这些复杂变化决定了细胞的命运，但直到最近，在细胞培养系统中模拟仍然具有挑战性。基于水凝胶的生物材料由于其高含水量、类似软组织的弹性以及通常可调节的生化含量，非常适合模拟这些体内环境。此外，水凝胶可以被设计为随着时间的推移实现基质特性的变化，以更好地模拟动态的天然微环境，以探测和指导干细胞的功能和命运。本综述将重点关注形成基于水凝胶的生物材料的技术，并在细胞培养过程中使用选择性加成反应、裂解反应或非共价相互作用及时修改其特性。还将讨论这些技术在四个维度（即随时间变化的三个维度）干细胞培养中的最新应用，以研究基本的干细胞过程。