title: Morphological properties of collagen fibers in porcine lamina propria.
abstract: OBJECTIVE
  Collagen influences the biomechanical properties of vocal folds. Altered collagen morphology has been implicated in dysphonia associated with aging and scarring. Documenting the morphological properties of native collagen in healthy vocal folds is essential to understand the structural and functional alterations to collagen with aging and disease. Our primary objective was to quantify the morphological properties of collagen in the vocal fold lamina propria. Our secondary exploratory objective was to investigate the effects of pepsin exposure on the morphological properties of collagen in the lamina propria.
  
  
  METHODS
  Experimental, in vitro study with porcine model.
  
  
  METHODS
  Lamina propria was dissected from 26 vocal folds and imaged with atomic force microscopy (AFM). Morphological data on d-periodicity, diameter, and roughness of collagen fibers were obtained. To investigate the effects of pepsin exposure on collagen morphology, vocal fold surface was exposed to pepsin or sham challenge before lamina propria dissection and AFM imaging.
  
  
  RESULTS
  The d-periodicity, diameter, and roughness values for native vocal fold collagen are consistent with literature reports of collagen fibers in other body tissues. Pepsin exposure on vocal fold surface did not appear to change the morphological properties of collagen fibers in the lamina propria.
  
  
  CONCLUSIONS
  Quantitative data on collagen morphology were obtained at nanoscale resolution. Documenting collagen morphology in healthy vocal folds is critical for understanding the physiological changes to collagen with aging and scarring and for designing biomaterials that match the native topography of lamina propria.
authors.affiliation: Biomedical Engineering, The School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA.
authors.forename: Iecun
authors.initials: I
authors.lastname: Johanes
authors.forename: Elaine
authors.initials: E
authors.lastname: Mihelc
authors.forename: Mahalakshmi
authors.initials: M
authors.lastname: Sivasankar
authors.forename: Albena
authors.initials: A
authors.lastname: Ivanisevic
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D024022:Fibrillar Collagens / Q000378:metabolism / Q000648:ultrastructure*; D007820:Laryngeal Mucosa / Q000378:metabolism / Q000648:ultrastructure*; D018625:Microscopy, Atomic Force; D010434:Pepsin A / Q000378:metabolism; D013499:Surface Properties; D013552:Swine; D014827:Vocal Cords / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D024022:Fibrillar Collagens; D010434:Pepsin A