title: Fine structure and molecular content of human chondrocytes encapsulated in alginate beads.
abstract: Preservation of the chondrocytic phenotype in vitro requires a 3D (three-dimensional) culture model. Diverse biomaterials have been tested as scaffolds for culture of animal chondrocytes; however, to date, none is considered a gold standard in regenerative medicine. Here, we studied the fine structure and the GAGs (glycosaminoglycans) content of human chondrocytes encapsulated in alginate beads by using electron microscopy and radioactive sulfate [35S] incorporation, respectively. Cells were obtained from human cartilage, encapsulated in alginate beads and cultured for 28 days. [35S]Na2SO4 was added to the culture media and later isolated for quantification of the sulfated GAGs found in three compartments: IC (intracellular), IB (intra-bead) and EB (extra-bead). Round cells were seen isolated or forming small groups throughout the alginate. Human chondrocytes presented the features of active cells such as euchromatic nuclei, abundant RER (rough endoplasmic reticulum) and many transport vesicles. We observed an extracellular matrix rich in collagen fibres and electrondense material adjacent to the cells. Most of the GAGs produced (74%) were found in the culture medium (EB), indicating that alginate has a limited capacity to retain the GAGs. CS (chondroitin sulfate), the major component of aggrecan, was the most prominent GAG produced by the encapsulated cells. Human chondrocytes cultured in alginate can sustain their phenotype, confirming the potential application of this biomaterial for cartilage engineering.
authors.affiliation: Institute of Biomedical Sciences, Center of Health Sciences, Federal University of Rio de Janeiro, Rio de Janeiro RJ, Brazil. andrade@histo.ufrj.br
authors.forename: Leonardo Rodrigues
authors.initials: LR
authors.lastname: Andrade
authors.forename: Katia Denise S
authors.initials: KD
authors.lastname: Arcanjo
authors.forename: Humberto Saramago H L
authors.initials: HS
authors.lastname: Martins
authors.forename: João Sergio Nobre
authors.initials: JS
authors.lastname: dos Reis
authors.forename: Marcos
authors.initials: M
authors.lastname: Farina
authors.forename: Radovan
authors.initials: R
authors.lastname: Borojevic
authors.forename: Maria Eugenia Leite
authors.initials: ME
authors.lastname: Duarte
mesh_terms: D000464:Alginates / Q000737:chemistry*; D002356:Cartilage / Q000166:cytology; D018929:Cell Culture Techniques; D019902:Chondrocytes / Q000378:metabolism*; D006025:Glycosaminoglycans / Q000032:analysis; D006801:Humans; D008854:Microscopy, Electron; D013462:Sulfur Radioisotopes / Q000737:chemistry / Q000378:metabolism; D023822:Tissue Engineering
chemical_list: D000464:Alginates; D006025:Glycosaminoglycans; D013462:Sulfur Radioisotopes