title: High seeding density of human chondrocytes in agarose produces tissue-engineered cartilage approaching native mechanical and biochemical properties.
abstract: Animal cells have served as highly controllable model systems for furthering cartilage tissue engineering practices in pursuit of treating osteoarthritis. Although successful strategies for animal cells must ultimately be adapted to human cells to be clinically relevant, human chondrocytes are rarely employed in such studies. In this study, we evaluated the applicability of culture techniques established for juvenile bovine and adult canine chondrocytes to human chondrocytes obtained from fresh or expired osteochondral allografts. Human chondrocytes were expanded and encapsulated in 2% agarose scaffolds measuring ∅3-4mm×2.3mm, with cell seeding densities ranging from 15 to 90×10(6)cells/mL. Subsets of constructs were subjected to transient or sustained TGF-β treatment, or provided channels to enhance nutrient transport. Human cartilaginous constructs physically resembled native human cartilage, and reached compressive Young's moduli of up to ~250kPa (corresponding to the low end of ranges reported for native knee cartilage), dynamic moduli of ~950kPa (0.01Hz), and contained 5.7% wet weight (%/ww) of glycosaminoglycans (≥ native levels) and 1.5%/ww collagen. We found that the initial seeding density had pronounced effects on tissue outcomes, with high cell seeding densities significantly increasing nearly all measured properties. Transient TGF-β treatment was ineffective for adult human cells, and tissue construct properties plateaued or declined beyond 28 days of culture. Finally, nutrient channels improved construct mechanical properties, presumably due to enhanced rates of mass transport. These results demonstrate that our previously established culture system can be successfully translated to human chondrocytes.
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Cigan
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
authors.forename: Brendan L
authors.initials: BL
authors.lastname: Roach
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Nims
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
authors.forename: Andrea R
authors.initials: AR
authors.lastname: Tan
authors.affiliation: Department of Materials, Imperial College London, London, UK.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Albro
authors.affiliation: University of Missouri, Columbia, MO, USA.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Stoker
authors.affiliation: University of Missouri, Columbia, MO, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Cook
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA; Department of Medicine, Columbia University, New York, NY 10032, USA.
authors.forename: Gordana
authors.initials: G
authors.lastname: Vunjak-Novakovic
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
authors.forename: Clark T
authors.initials: CT
authors.lastname: Hung
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA; Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA. Electronic address: ateshian@columbia.edu.
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Ateshian
mesh_terms: D000293:Adolescent; D000328:Adult; D002356:Cartilage / Q000737:chemistry / Q000502:physiology*; D002452:Cell Count; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology* / Q000187:drug effects; D003094:Collagen / Q000032:analysis; D046508:Culture Techniques; D055119:Elastic Modulus; D005260:Female; D006025:Glycosaminoglycans / Q000032:analysis; D006801:Humans; D008297:Male; D011312:Pressure; D012685:Sepharose; D023822:Tissue Engineering / Q000379:methods*; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D055815:Young Adult
chemical_list: D006025:Glycosaminoglycans; D016212:Transforming Growth Factor beta; D003094:Collagen; D012685:Sepharose
keywords: Agarose; Allografts; Cartilage; Chondrocytes; Human; Tissue Engineering