title: Differentiation of respiratory epithelium in a 3-dimensional co-culture with fibroblasts embedded in fibrin gel.
abstract: BACKGROUND
  Tracheal tissue engineering is a promising option for the treatment of tracheal defects. In a previous study we proved the suitability of fibrin gel as a scaffold for tracheal tissue engineering. This study investigates whether the differentiation of respiratory epithelium can be increased by culturing epithelial cells in a three dimensional system containing fibroblasts embedded into fibrin gel.
  
  
  METHODS
  Respiratory epithelial cells were isolated from porcine trachea, seeded onto a fibrin gel and kept in air-liquid-interface culture for 33 days. Morphology as well as pan-cytokeratin, MUC5AC and claudin-1 expression of cells cultured on pure fibrin gel were compared to culture on gels containing fibroblasts.
  
  
  RESULTS
  After two weeks, cells seeded on pure fibrin gel were multilayered, showed hyperproliferation and dedifferentiation. Co-cultured cells built up a pseudostratified epithelium. The differentiation and organization of epithelial structure improved with respect to time. After four weeks, morphology of the co-cultured respiratory epithelium resembled native tracheal epithelium. Immunohistochemistry showed that respiratory epithelium co-cultured with fibroblasts had an increasing similarity of pan-cytokeratin expression compared to native trachea. Cells cultured without fibroblasts differed in pan-cytokeratin expression from native trachea and did not show any improvement of differentiation. Immunohistochemical staining of MUC5AC and claudin-1 proved seeded cells being respiratory epithelial cells.
  
  
  CONCLUSIONS
  This study indicates that adding fibroblasts to fibrin gel positively influences the differentiation of respiratory epithelium.
authors.affiliation: Department of Tissue Engineering & Textile Implants, Institute for Applied Medical Engineering, Helmholtz Institute of the RWTH University Hospital, Pauwelsstr. 20, 52074 Aachen, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Albers
authors.affiliation: Department of Tissue Engineering & Textile Implants, Institute for Applied Medical Engineering, Helmholtz Institute of the RWTH University Hospital, Pauwelsstr. 20, 52074 Aachen, Germany.
authors.forename: Anja Lena
authors.initials: AL
authors.lastname: Thiebes
authors.affiliation: Department of Tissue Engineering & Textile Implants, Institute for Applied Medical Engineering, Helmholtz Institute of the RWTH University Hospital, Pauwelsstr. 20, 52074 Aachen, Germany.
authors.forename: Kai L
authors.initials: KL
authors.lastname: Gessenich
authors.affiliation: Department for Internal Medicine - Section for Pneumology, University Hospital Aachen, Pauwelsstraße 30, Aachen, Germany ; Department of Tissue Engineering & Textile Implants, Institute for Applied Medical Engineering, Helmholtz Institute of the RWTH University Hospital, Pauwelsstr. 20, 52074 Aachen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Jockenhoevel
authors.affiliation: Department for Internal Medicine - Section for Pneumology, University Hospital Aachen, Pauwelsstraße 30, Aachen, Germany ; Department of Tissue Engineering & Textile Implants, Institute for Applied Medical Engineering, Helmholtz Institute of the RWTH University Hospital, Pauwelsstr. 20, 52074 Aachen, Germany.
authors.forename: Christian G
authors.initials: CG
authors.lastname: Cornelissen
keywords: Airways; Fibrin gel; Fibroblast; Respiratory epithelium; Tissue engineering