Abstract
The development of perfusable and multiscale vascular networks remains one of the largest challenges in tissue engineering. As such, there is a need for the creation of customizable and facile methods to produce robustly vascularized constructs. In this study, secondarily crosslinkable (clickable) poly(ethylene glycol)-norbornene (PEGNB) microbeads were produced and evaluated for their ability to sequentially support suspension bioprinting and microvascular self-assembly towards the aim of engineering hierarchical vasculature. The clickable PEGNB microbead slurry exhibited mechanical behavior suitable for suspension bioprinting of sacrificial bioinks, could be UV crosslinked into a granular construct post-print, and withstood evacuation of the bioink and subsequent perfusion of the patterned void space. Endothelial and stromal cells co-embedded within jammed RGD-modified PEGNB microbead slurries assembled into capillary-scale vasculature after secondary crosslinking of the beads into granular constructs, with endothelial tubules forming within the interstitial space between microbeads and supported by the perivascular association of the stromal cells. Microvascular self-assembly was not impacted by printing sacrificial bioinks into the cell-laden microbead support bath before UV crosslinking. Collectively, these results demonstrate that clickable PEGNB microbeads are a versatile substrate for both suspension printing and microvascular culture and may be the foundation for a promising methodology to engineer hierarchical vasculature.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Irene W. Zhang: zirene{at}umich.edu, Lucia S. Choi: luchoi{at}umich.edu, Nicole E. Friend: Nicole.Friend-1{at}colorado.edu, Atticus J. McCoy: atticusm{at}umich.edu, Firaol S. Midekssa: firaol{at}umich.edu, Eben Alsberg: ealsberg{at}uic.edu, Sasha Cai Lesher-Pérez: sashacai{at}umich.edu, Jan P. Stegemann: jpsteg{at}umich.edu, Brendon M. Baker: bambren{at}umich.edu
Data Availability Statement: The data that support the findings in this study are available from the corresponding author upon reasonable request.
Funding Statement: Research reported in this publication was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health under Award Number R01-HL085339 and the Leland Professorship endowment. IWZ was partially supported by the Cellular Biotechnology Training Program at the University of Michigan (T32-GM145304). NEF was partially supported by the Tissue Engineering and Regeneration Training Program at the University of Michigan (T32-DE007057) and the Rackham Merit Fellowship. AJM was partially supported by the Training Program in Translational Cardiovascular Research and Entrepreneurship at the University of Michigan (T32-HL125242). BMB and FSM acknowledge support from NIH (R01-EB030474), the National Science Foundation (CELL-MET ERC, EEC-1647837), and a Scientific Research Initiative grant from the Biosciences Initiative of the University of Michigan. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the National Science Foundation.
Conflict of Interest Disclosure: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
