title: Nanostructuring biosynthetic hydrogels for tissue engineering: a cellular and structural analysis.
abstract: The nanostructuring of hydrogel scaffolds used in tissue engineering provides the ability to control cellular fate and tissue morphogenesis through cell-matrix interactions. Here we describe a method to provide nanostructure to a biosynthetic hydrogel scaffold made from crosslinked poly(ethylene glycol)-fibrinogen conjugates (PEG-fibrinogen), by modifying them with the block-copolymer Pluronic® F127. The copolymeric additive self-assembled into micelles at certain concentrations and temperatures, thereby creating nanostructures within the crosslinked hydrogel. Small-angle X-ray scattering (SAXS) and transmission electron microscopy at cryogenic temperature were used to detect Pluronic® F127 micelles embedded within the crosslinked PEG-fibrinogen hydrogels. The density and order of the micelles within the hydrogel matrix increased as the relative Pluronic® F127 concentration was raised. The transient stability of the micelles within the hydrogel network was analyzed using time-dependent swelling and Pluronic® F127 release measurements. These characterizations revealed that most of the Pluronic® F127 molecules diffuse out of the hydrogels after 4 days in aqueous buffer and SAXS analysis confirmed a significant change in the structure and interactions of the micelles during this time. Cell culture experiments evaluating the three-dimensional fibroblast morphology within the matrix indicated a strong correlation between cell spreading and the hydrogel's characteristic mesh size. The present research thereby provides a more quantitative understanding of how structural features in an encapsulating hydrogel environment can affect cell morphogenesis towards tissue regeneration.
authors.affiliation: Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Ilya
authors.initials: I
authors.lastname: Frisman
authors.forename: Dror
authors.initials: D
authors.lastname: Seliktar
authors.forename: Havazelet
authors.initials: H
authors.lastname: Bianco-Peled
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry*; D002021:Buffers; D002478:Cells, Cultured; D020285:Cryoelectron Microscopy; D005340:Fibrinogen / Q000737:chemistry; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D020100:Hydrogels / Q000138:chemical synthesis / Q000737:chemistry*; D008823:Micelles; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D020442:Poloxamer / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D053838:Scattering, Small Angle; D013501:Surface-Active Agents / Q000737:chemistry; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D001672:Biocompatible Materials; D002021:Buffers; D020100:Hydrogels; D008823:Micelles; D013501:Surface-Active Agents; D020442:Poloxamer; D011092:Polyethylene Glycols; D005340:Fibrinogen