Dept. of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA.
Dept. of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA.
Biomater Sci. 2022 Nov 22;10(23):6768-6777. doi: 10.1039/d2bm01349e.
During differentiation, neural stem cells (NSCs) encounter diverse cues from their niche, including not only biophysical cues from the extracellular matrix (ECM) but also cell-cell communication. However, it is still poorly understood how these cues cumulatively regulate mechanosensitive NSC fate commitment, especially in 3D matrices that better mimic systems. Here, we develop a click chemistry-based 3D hydrogel material system to fully decouple cell-cell and cell-ECM interactions by functionalizing small peptides: the HAVDI motif from N-cadherin and RGD motif from fibronectin. The hydrogel is engineered to range in stiffness from 75 Pa to 600 Pa. Interestingly, HAVDI-mediated interaction shows increased neurogenesis, except for the softest gel (75 Pa). Moreover, the HAVDI ligation attenuates the mechanosensing state of NSCs, exhibiting restricted cytoskeletal formation and RhoA signaling. Given that mechanosensitive neurogenesis has been reported to be regulated by cytoskeletal formation, our finding suggests that the enhanced neurogenesis in the HAVDI-modified gel may be highly associated with the HAVDI interaction-mediated attenuation of mechanosensing. Furthermore, NSCs in the HAVDI gel shows higher β-catenin activity, which has been known to promote neurogenesis. Our findings provide critical insights into how mechanosensitive NSC fate commitment is regulated as a consequence of diverse interactions in 3D microenvironments.
在分化过程中，神经干细胞（NSCs）会受到来自其微环境的各种信号的影响，这些信号不仅包括来自细胞外基质（ECM）的生物物理信号，还包括细胞间的通讯。然而，这些信号如何累积调节机械敏感的 NSC 命运决定，特别是在更好地模拟系统的 3D 基质中，目前仍知之甚少。在这里，我们开发了一种基于点击化学的 3D 水凝胶材料系统，通过功能化小肽来完全解偶联细胞-细胞和细胞-ECM 相互作用：来自 N-钙粘蛋白的 HAVDI 基序和来自纤连蛋白的 RGD 基序。该水凝胶的弹性范围从 75 Pa 到 600 Pa。有趣的是，除了最软的凝胶（75 Pa）外，HAVDI 介导的相互作用显示出增加的神经发生。此外，HAVDI 连接减弱了 NSCs 的机械感知状态，表现为限制的细胞骨架形成和 RhoA 信号。鉴于机械敏感的神经发生已被报道受细胞骨架形成调节，我们的发现表明，HAVDI 修饰凝胶中增强的神经发生可能与 HAVDI 相互作用介导的机械感知衰减高度相关。此外，HAVDI 凝胶中的 NSCs 表现出更高的β-连环蛋白活性，已知该活性可促进神经发生。我们的研究结果为机械敏感的 NSC 命运决定如何作为 3D 微环境中各种相互作用的结果进行调节提供了重要的见解。
