title: Phage as versatile nanoink for printing 3-D cell-laden scaffolds.
abstract: Bioprinting is an emerging technology for producing tissue-mimetic 3-D structures using cell-containing hydrogels (bioink). Various synthetic and natural hydrogels with key characteristics, including biocompatibility, biodegradability, printability and crosslinkability, have been employed as ink materials in bioprinting. Choosing the right cell-containing "bioink" material is the most essential step for fabricating 3-D constructs with a controlled mechanical and biochemical microenvironment that can lead to successful tissue regeneration and repair. Here, we demonstrate that the genetically engineered M13 phage holds great potential for use as a versatile nanoink for printing 3-D cell-laden matrices. In particular, M13 phages displaying integrin-binding (GRGDS) and calcium-binding (DDYD) domains on their surface were blended with alginate to successfully form Ca(2+)-crosslinked hydrogels. Furthermore, 3-D cell-laden scaffolds with high cell viability were generated after optimizing the printing process. The MC3T3-E1 cells within these scaffolds showed enhanced proliferation and differentiation rates that increased proportionally with the concentration of phages in the 3-D matrices compared with the rates of cells in pure alginate scaffolds.
  
  
  CONCLUSIONS
  Bioprinting is an emerging technology for producing tissue-mimetic 3-D structures using cell-containing hydrogels called bioink. Choosing the right bioink is essential for fabricating 3-D structures with controlled mechanical and biochemical properties which lead to successful tissue regeneration. Therefore, there is a growing demand for a new bioink material that can be designed from molecular level. Here, we demonstrate that genetically engineered M13 phage holds great potential for use as versatile bioink. The phage-based bioink benefits from its replicability, self-assembling property, and tunable molecular design and enables bioprinted scaffolds to exhibit improved cell viability, proliferation and differentiation. This study opens the door for the development of genetically tunable nanofibrous bioink materials which closely mimic natural structural proteins in the extracellular matrix.
authors.affiliation: Department of Genetic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Doe-Young
authors.initials: DY
authors.lastname: Lee
authors.affiliation: Department of Biomechatronic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Hyeongjin
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Biomechatronic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: YongBok
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Research Institute for Convergence of Biomedical Science and Technology, Pusan National University, Yangsan Hospital, Yangsan 626-770, Republic of Korea.
authors.forename: So Young
authors.initials: SY
authors.lastname: Yoo
authors.affiliation: Department of Genetic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea. Electronic address: wjchung@skku.edu.
authors.forename: Woo-Jae
authors.initials: WJ
authors.lastname: Chung
authors.affiliation: Department of Biomechatronic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea. Electronic address: gkimbme@skku.edu.
authors.forename: GeunHyung
authors.initials: G
authors.lastname: Kim
mesh_terms: D000818:Animals; D017104:Bacteriophage M13 / Q000737:chemistry* / Q000235:genetics; D002460:Cell Line; D020100:Hydrogels / Q000737:chemistry*; D051379:Mice; D053758:Nanoparticles / Q000737:chemistry*; D019151:Peptide Library; D066330:Printing, Three-Dimensional; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D020100:Hydrogels; D019151:Peptide Library
keywords: 3-D scaffolds; Bioinks; Bioprinting; Genetic engineering; Phages; Tissue engineering