The Rapid Generation of Cell-Laden, FACS-Compatible Collagen Gels
Yi Xiao,
Qiaoling Huang,
Jesse W. Collins,
Julie Brouchon,
Jeffery A. Nelson,
Zachary Niziolek,
Alison O’Neil,
Fangfu Ye,
David A. Weitz,
John A. Heyman
Affiliations
Yi Xiao
Experimental Soft Condensed Matter Group, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
Qiaoling Huang
Department of Physics, Xiamen University, Xiamen 361005, China
Jesse W. Collins
Experimental Soft Condensed Matter Group, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
Julie Brouchon
Experimental Soft Condensed Matter Group, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
Jeffery A. Nelson
Faculty of Arts and Sciences, Bauer Flow Cytometry Core, Harvard University, Cambridge, MA 02138, USA
Zachary Niziolek
Experimental Soft Condensed Matter Group, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
Alison O’Neil
Department of Chemistry, Wesleyan University, Middletown, CT 06459, USA
Fangfu Ye
Oujiang Laboratory (Zhejiang Laboratory for Regenerative Medicine, Vision and Brain Health), Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325000, China
David A. Weitz
Experimental Soft Condensed Matter Group, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
John A. Heyman
Experimental Soft Condensed Matter Group, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
A three-dimensional cell culture in hydrogel beads can support cell growth and differentiation into multi-cellular structures, and these gel beads could be used as building blocks for more complex three-dimensional assemblies. This requires hydrogel beads that are robust enough to sort via FACS yet can be degraded by cell-secreted enzymes. Collagen polymers form hydrogels that are excellent cell growth substrates; however, collagen-containing hydrogel beads typically include additional polymers that limit their degradation. Here, we introduce a simple microfluidic method to generate robust, sortable, cell-laden collagen hydrogel beads. We use on-device pH control to trigger collagen gelation without exposing cells to low pH, ensuring high cell viability. We fabricate microfluidic devices to generate droplets with a wide size range, as demonstrated by production of both small (~55 µm diameter) and large (~300 µm diameter) collagen gels. All hydrogels are sufficiently robust to allow for sorting using FACS. Moreover, high cell viability is maintained throughout the process.
