title: Engineering a morphogenetically active hydrogel for bioprinting of bioartificial tissue derived from human osteoblast-like SaOS-2 cells.
abstract: Sodium alginate hydrogel, stabilized with gelatin, is a suitable, biologically inert matrix that can be used for encapsulating and 3D bioprinting of bone-related SaOS-2 cells. However, the cells, embedded in this matrix, remain in a non-proliferating state. Here we show that addition of an overlay onto the bioprinted alginate/gelatine/SaOS-2 cell scaffold, consisting of agarose and the calcium salt of polyphosphate [polyP·Ca(2+)-complex], resulted in a marked increase in cell proliferation. In the presence of 100 μm polyP·Ca(2+)-complex, the cells proliferate with a generation time of approximately 47-55 h. In addition, the hardness of the alginate/gelatin hydrogel substantially increases in the presence of the polymer. The reduced Young's modulus for the alginate/gelatin hydrogel is approximately 13-14 kPa, and this value drops to approximately 0.5 kPa after incubation of the cell containing scaffolds for 5 d. In the presence of 100 μm polyP·Ca(2+)-complex, the reduced Young's modulus increases to about 22 kPa. The hardness of the polyP·Ca(2+)-complex containing hydrogel remains essentially constant if cells are absent in the matrix, but it drops to 3.2 kPa after a 5 d incubation period in the presence of SaOS-2 cells, indicating that polyP·Ca(2+)-complex becomes metabolized, degraded, by the cells. The alginate/gelatine-agarose system with polyP·Ca(2+)-complex cause a significant increase in the mineralization of the cells. SEM analyses revealed that the morphology of the mineral nodules formed on the surface of the cells embedded in the alginate/gelatin hydrogel do not significantly differ from the nodules on cells growing in monolayer cultures. The newly developed technique, using cells encapsulated into an alginate/gelatin hydrogel and a secondary layer containing the morphogenetically active, growth promoting polymer polyP·Ca(2+)-complex opens new possibilities for the application of 3D bioprinting in bone tissue engineering.
authors.affiliation: ERC Advanced Investigator Grant Research Group at The Institute for Physiological Chemistry, University Medical Center of The Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany.
authors.forename: Meik
authors.initials: M
authors.lastname: Neufurth
authors.affiliation: ERC Advanced Investigator Grant Research Group at The Institute for Physiological Chemistry, University Medical Center of The Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany. Electronic address: wang013@uni-mainz.de.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Wang
authors.affiliation: ERC Advanced Investigator Grant Research Group at The Institute for Physiological Chemistry, University Medical Center of The Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany.
authors.forename: Heinz C
authors.initials: HC
authors.lastname: Schröder
authors.affiliation: School of Materials Science and Engineering, Tsinghua University, 100084 Beijing, China.
authors.forename: Qingling
authors.initials: Q
authors.lastname: Feng
authors.affiliation: NanotecMARIN GmbH, Duesbergweg 6, D-55128 Mainz, Germany.
authors.forename: Bärbel
authors.initials: B
authors.lastname: Diehl-Seifert
authors.affiliation: Department of Oral and Maxillifacial Surgery, University Medicine Mainz, Augustusplatz 2, 55131 Mainz, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ziebart
authors.affiliation: ERC Advanced Investigator Grant Research Group at The Institute for Physiological Chemistry, University Medical Center of The Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: Steffen
authors.affiliation: ERC Advanced Investigator Grant Research Group at The Institute for Physiological Chemistry, University Medical Center of The Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany.
authors.forename: Shunfeng
authors.initials: S
authors.lastname: Wang
authors.affiliation: ERC Advanced Investigator Grant Research Group at The Institute for Physiological Chemistry, University Medical Center of The Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany. Electronic address: wmueller@uni-mainz.de.
authors.forename: Werner E G
authors.initials: WEG
authors.lastname: Müller
mesh_terms: D000464:Alginates / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry*; D062028:Bioprinting / Q000379:methods*; D002460:Cell Line; D049109:Cell Proliferation; D055119:Elastic Modulus; D005780:Gelatin / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006244:Hardness; D006603:Hexuronic Acids / Q000737:chemistry; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D010006:Osteoblasts / Q000166:cytology*; D011122:Polyphosphates / Q000737:chemistry; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D000464:Alginates; D001672:Biocompatible Materials; D006603:Hexuronic Acids; D011122:Polyphosphates; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020723:Glucuronic Acid; D005780:Gelatin
keywords: Bioartificial bone; Bioprinting; Osteoblasts; Polyphosphate; SaOS-2 cells; Tissue engineering