title: Visible light crosslinkable chitosan hydrogels for tissue engineering.
abstract: In situ gelling constructs, which form a hydrogel at the site of injection, offer the advantage of delivering cells and growth factors to the complex structure of the defect area for tissue engineering. In the present study, visible light crosslinkable hydrogel systems were presented using methacrylated glycol chitosan (MeGC) and three blue light initiators: camphorquinone (CQ), fluorescein (FR) and riboflavin (RF). A minimal irradiation time of 120 s was required to produce MeGC gels able to encapsulate cells with CQ or FR. Although prolonged irradiation up to 600 s improved the mechanical strength of CQ- or FR-initiated gels (compressive modulus 2.8 or 4.4 kPa, respectively), these conditions drastically reduced encapsulated chondrocyte viability to 5% and 25% for CQ and FR, respectively. Stable gels with 80-90% cell viability could be constructed using radiofrequency (RF) with only 40s irradiation time. Increasing irradiation time up to 300s significantly improved the compressive modulus of the RF-initiated MeGC gels up to 8.5 kPa without reducing cell viability. The swelling ratio and degradation rate were smaller at higher irradiation time. RF-photoinitiated hydrogels supported proliferation of encapsulated chondrocytes and extracellular matrix deposition. The feasibility of this photoinitiating system as in situ gelling hydrogels was further demonstrated in osteochondral and chondral defect models for potential cartilage tissue engineering. The MeGC hydrogels using RF offer a promising photoinitiating system in tissue engineering applications.
authors.affiliation: Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, University of California, Los Angeles, CA 90095, USA.
authors.forename: Junli
authors.initials: J
authors.lastname: Hu
authors.forename: Yaping
authors.initials: Y
authors.lastname: Hou
authors.forename: Hyejin
authors.initials: H
authors.lastname: Park
authors.forename: Bogyu
authors.initials: B
authors.lastname: Choi
authors.forename: Siying
authors.initials: S
authors.lastname: Hou
authors.forename: Amy
authors.initials: A
authors.lastname: Chung
authors.forename: Min
authors.initials: M
authors.lastname: Lee
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000528:radiation effects; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D048271:Chitosan / Q000737:chemistry* / Q000528:radiation effects; D019902:Chondrocytes / Q000166:cytology* / Q000502:physiology*; D003432:Cross-Linking Reagents / Q000737:chemistry* / Q000528:radiation effects; D004867:Equipment Design; D020100:Hydrogels / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D011817:Rabbits; D023822:Tissue Engineering / Q000295:instrumentation*; D054457:Tissue Scaffolds
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D020100:Hydrogels; D048271:Chitosan