Microenvironmental control of adult stem cell differentiation: Influence of biochemical ECM composition, ECM stiffness and electric fields

细胞发育在很大程度上依赖于细胞微环境提供的大量生化和物理信号。传统上，体外实验研究集中于一种信号类型的影响，而不是忠实地概括在体内占主导地位的复杂和动态的信号。然而，越来越清楚的是，各种信号--本质上是生化的和物理的--相互作用很强，特别是这些刺激的组合对于末端分化是必不可少的。因此，本项目的目的是研究多种生化(基质组成)和生物物理(基质硬度、电场)信号在联合作用中对人MSCs分化行为的影响。特别是，将设计一种包含各种细胞外基质分子的混合三明治凝胶，以胶原为基础，结合选定的GAG-衍生物，并评估其在诱导MSCs差异反应方面的有效性。此外，凝胶的硬度将在很大范围内进行调整，以匹配天然组织的顺应性，如脂肪(~2 kpa)、软骨(~20 kpa)和预钙化骨骼(~40 kpa)。此外，通过附加电场的应用，本项目的目的是确定最适合成骨分化的参数集，并初步了解信号通路如何受到这种联合刺激的影响。总体而言，该项目将为细胞分化过程提供新的见解。了解这种复杂的细胞-材料-相互作用将为设计和开发新的组织工程结构创造新的机会。

Cellular development is strongly dependent on numerous biochemical and physical signals provided by the cellular microenvironment. Traditionally, in vitro experimental studies concentrate on the influence of one signaling type and do not faithfully recapitulate the complex and dynamic signaling that predominates in vivo. However, it is increasingly clear that various signals - both of biochemical and physical in nature - interact strongly with each other and especially the combination of these stimuli is essential for terminal differentiation. Thus, the aim of this project is to study the interaction of multiple biochemical (matrix composition) and biophysical (matrix stiffness, electric fields) signals in their combined effects on differentiation behavior of human MSCs. In particular, a hybrid-sandwich gel incorporating various ECM molecules, based on collagen in combination with selected GAG-derivatives, will be designed and evaluated for its efficacy in eliciting differential response in MSCs. Moreover, the stiffness of the gel will be tailored over a wide range, to match the compliance of native tissues such as adipose (~ 2 kPa), cartilage (~ 20 kPa) and pre-calcified bone (~ 40 kPa). Further, by the additional application of electric field this project intent to determine the parameters sets best suited for osteogenic differentiation and to gain a first understanding of how signaling pathways are influenced by such combined stimulations. Overall, this project will provide new insights into the cellular differentiation process. Understanding such complex cell-material-interactions will create new opportunities for designing and developing novel tissue engineering constructs.