Singhal Diya, Christakopoulos Fotis, Brunel Lucia G, Borkar Suraj, Doulames Vanessa M, Myung David, Fuller Gerald G, Heilshorn Sarah C
Department of Chemical Engineering, Stanford University, Stanford, CA, USA.
Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA.
bioRxiv. 2025 May 25:2025.05.20.654730. doi: 10.1101/2025.05.20.654730.
Natural tissue comprises fibrous proteins with complex fiber alignment patterns. Here, we develop a reproducible method to fabricate biomimetic scaffolds with patterned fiber alignment along multiple orientations. While extrusion-based approaches are commonly used to align fibrous polymers in a single orientation parallel to the direction of flow, we hypothesized that extrusion-based 3D printing could be utilized to achieve more complex patterns of fiber alignment. Specifically, we show control of lateral spreading of a printed filament can induce fiber alignment that is either parallel or perpendicular to the flow direction. Theoretical prediction of the printing parameters that control fiber orientation was experimentally validated using a collagen biomaterial ink. The velocity ratio of the printhead movement relative to the ink extrusion rate was found to dictate collagen fiber alignment, allowing for the informed fabrication of collagen scaffolds with prescribed patterns of fiber alignment. For example, controlled variation of the ink extrusion rate during a single print resulted in scaffolds with specified regions of both parallel and perpendicular collagen fiber alignment. Human corneal mesenchymal stromal cells seeded onto the printed scaffolds adopted a spread morphology that aligned with the underlying collagen fiber patterns. This technique worked well for filaments either printed into air or extruded within a support bath using embedded 3D printing, enabling the fabrication of 3D structures with aligned collagen fibers. Taken together, this work demonstrates a theoretical and experimental framework to achieve the reproducible fabrication of 3D printed structures with controlled collagen fiber patterns that guide cellular alignment.
天然组织由具有复杂纤维排列模式的纤维蛋白组成。在此,我们开发了一种可重复的方法来制造具有沿多个方向排列的图案化纤维的仿生支架。虽然基于挤出的方法通常用于使纤维状聚合物沿与流动方向平行的单一方向排列,但我们推测基于挤出的3D打印可用于实现更复杂的纤维排列模式。具体而言,我们表明控制打印细丝的横向扩散可以诱导与流动方向平行或垂直的纤维排列。使用胶原生物材料墨水对控制纤维取向的打印参数进行了理论预测并通过实验验证。发现打印头移动速度与墨水挤出速率的比率决定了胶原纤维的排列,从而能够明智地制造具有规定纤维排列模式的胶原支架。例如,在单次打印过程中控制墨水挤出速率的变化会导致支架具有平行和垂直胶原纤维排列的特定区域。接种到打印支架上的人角膜间充质基质细胞呈现出与下面的胶原纤维模式对齐的铺展形态。该技术对于打印到空气中或使用嵌入式3D打印在支撑浴中挤出的细丝都很有效,能够制造具有排列胶原纤维的3D结构。综上所述,这项工作展示了一个理论和实验框架,以实现具有可控胶原纤维模式的3D打印结构的可重复制造,该模式可指导细胞排列。