title: Zonal chondrocytes seeded in a layered agarose hydrogel create engineered cartilage with depth-dependent cellular and mechanical inhomogeneity.
abstract: We hypothesized that zonal populations of chondrocytes seeded into a bilayered scaffold with initially prescribed depth-varying, compressive material properties will lead to a biomimetic cartilage tissue construct with depth-dependent cellular and compressive mechanical inhomogeneity similar to that of the native tissue. Superficial zone chondrocytes (SZCs) and middle/deep zone chondrocytes (MDZCs) were isolated and encapsulated with 2% or 3% agarose to form single-layered constructs of 2% SZC, 3% SZC, 2% MDZC; bilayered constructs of 2% SZC/2% MDZC and 3% SZC/2% MDZC; and 2% mixed chondrocyte controls. For SZCs on day 42, increased glycosaminoglycan (GAG) and collagen was found with increased agarose concentration and when layered with MDZCs. Superficial zone protein increased with agarose concentration in bilayered constructs. For MDZCs, increased GAG content and regulation of cell proliferation was observed when layered with SZCs. Bilayered constructs possessed a depth-dependent compressive modulus qualitatively similar to that of native articular cartilage, whereas controls showed a U-shaped profile with stiffer peripheral edges and softer middle region. This study is the first to create an engineered cartilage tissue with depth-varying cellular as well as mechanical inhomogeneity. Future studies will determine if replicating inhomogeneity is advantageous in clinical applications of tissue engineered cartilage.
authors.affiliation: Department of Biomedical Engineering, Cellular Engineering Laboratory, Columbia University, New York 10027, USA.
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Ng
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Ateshian
authors.forename: Clark T
authors.initials: CT
authors.lastname: Hung
mesh_terms: D000818:Animals; D002356:Cartilage / Q000166:cytology* / Q000187:drug effects; D002417:Cattle; D002469:Cell Separation; D048430:Cell Shape / Q000187:drug effects; D019902:Chondrocytes / Q000166:cytology* / Q000187:drug effects; D003094:Collagen / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D055119:Elastic Modulus / Q000187:drug effects; D006025:Glycosaminoglycans / Q000378:metabolism; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000494:pharmacology; D007150:Immunohistochemistry; D055595:Mechanical Phenomena / Q000187:drug effects; D012685:Sepharose / Q000494:pharmacology; D023822:Tissue Engineering
chemical_list: D006025:Glycosaminoglycans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D003094:Collagen; D004247:DNA; D012685:Sepharose