title: Novel keratin preparation supports growth and differentiation of odontoblast-like cells.
abstract: OBJECTIVE
  To fabricate a keratin hydrogel, characterize its functionality as a biomaterial and investigate the effects of keratin on growth and differentiation of odontoblast-like cells.
  
  
  METHODS
  Keratins were extracted from sheep wool using a well-established technique. The extracted proteins were purified by dialysis, quantified by gel electrophoresis, mass spectrometry, amino acid analysis and inductively coupled mass spectrometry. The microstructure of the fabricated keratin hydrogels was studied by scanning electron microscopy, flow characteristics by rheometer, hydrolytic stability and cytocompatibility by Live/Dead(®) cell assay. Furthermore, the influence of keratin on odontoblast-like cells (MDPC-23) was assessed to confirm their bioactivity at different dilutions. Cell proliferation was studied using alamarBlue(®) assay and differentiation by alkaline phosphatase enzyme activity, alizarin red staining and calcium quantification, reverse transcription polymerase chain reaction (rt-PCR) and immunocytochemical staining for dentine matrix protein- 1 (DMP-1) expression. anova with Tukey's tests was performed for statistical comparison.
  
  
  RESULTS
  The characterized hydrogel was injectable with a highly porous architecture that underwent slow degradation, and its cytocompatibility was statistically equivalent to collagen hydrogel (P > 0.05). Cell proliferation and differentiation were enhanced at the optimal keratin concentration of 0.1 mg mL(-1) . At this concentration, the influence of keratin on cell differentiation was demonstrated by marked elevation in alkaline phosphatase activity (P < 0.05), calcium deposition (P < 0.01), gene expression (P < 0.01) and positive immunostaining for DMP-1.
  
  
  CONCLUSIONS
  The presence of keratin enhanced odontoblast cell behaviour. Keratin hydrogels may be a potential scaffold for pulp-dentine regen-eration.
authors.affiliation: Department of Anatomy, University of Otago, Dunedin, New Zealand.
authors.forename: L
authors.initials: L
authors.lastname: Ajay Sharma
authors.affiliation: Department of Applied Sciences, University of Otago, Dunedin, New Zealand.
authors.forename: M A
authors.initials: MA
authors.lastname: Ali
authors.affiliation: Department of Oral Rehabilitation, University of Otago, Dunedin, New Zealand.
authors.forename: R M
authors.initials: RM
authors.lastname: Love
authors.affiliation: Department of Anatomy, University of Otago, Dunedin, New Zealand.
authors.forename: M J
authors.initials: MJ
authors.lastname: Wilson
authors.affiliation: Department of Anatomy, University of Otago, Dunedin, New Zealand.
authors.forename: G J
authors.initials: GJ
authors.lastname: Dias
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D003782:Dental Pulp / Q000166:cytology; D007633:Keratins / Q000502:physiology*; D009804:Odontoblasts / Q000502:physiology*; D012756:Sheep; D014935:Wool
chemical_list: D007633:Keratins
keywords: bioactivity; hydrogel; odontoblasts; polymers; scaffold