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BMC Musculoskelet Disord. 2018 May 24;19(1):168. doi: 10.1186/s12891-018-2079-6.

Human osteochondritis dissecans fragment-derived chondrocyte characteristics ex vivo, after monolayer expansion-induced de-differentiation, and after re-differentiation in alginate bead culture.

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Center for Orthopaedic and Trauma Surgery, Klinikum Mittleres Erzgebirge, Alte Marienberger, Str. 52, 09405, Zschopau, Germany.
Department of Trauma, Hand and Reconstructive Surgery, Universitätsklinikum Jena, Erlanger Allee 101, 07747, Jena, Germany.
Department of Biochemistry, Rush Medical College, 1735 W. Harrison St, Chicago, IL, 60612, USA.
G.E.R.N. Tissue Replacement, Regeneration & Neogenesis, Department of Orthopedics and Trauma Surgery, Medical Center - Albert-Ludwigs-University of Freiburg, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Hugstetter Straße 55, 79106, Freiburg, Germany.
Massachusetts Institute of Technology, Center for Biomedical Engineering, 500 Technology Sq, Cambridge, MA, 02139, USA.



Autologous chondrocyte implantation (ACI) is a therapy for articular cartilage and osteochondral lesions that relies on notch- or trochlea-derived primary chondrocytes. An alternative cell source for ACI could be osteochondritis dissecans (OCD) fragment-derived chondrocytes. Assessing the potential of these cells, we investigated their characteristics ex vivo and after monolayer expansion, as monolayer expansion is an integral step of ACI. However, as monolayer expansion can induce de-differentiation, we asked whether monolayer-induced de-differentiation can be reverted through successive alginate bead culture.


Chondrocytes were isolated from the OCD fragments of 15 patient knees with ICRS grades 3-4 lesions for ex vivo analyses, primary alginate bead culture, monolayer expansion, and alginate bead culture following monolayer expansion for attempting re-differentiation. We determined yield, viability, and the mRNA expression of aggrecan and type I, II, and X collagen.


OCD fragment-derived chondrocyte isolation yielded high numbers of viable cells with a low type I:II collagen expression ratio (< 1) and a relatively high aggrecan and type II and X collagen mRNA expression, indicating chondrogenic and hypertrophic characteristics. As expected, monolayer expansion induced de-differentiation. Alginate bead culture of monolayer-expanded cells significantly improved the expression profile of all genes investigated, being most successful in decreasing the hypertrophy marker type X collagen to 1.5% of its ex vivo value. However, the chondrogenic phenotype was not fully restored, as the collagen type I:II expression ratio decreased significantly but remained > 1.


OCD fragment derived human chondrocytes may hold not yet utilized clinical potential for cartilage repair.


Alginate bead culture; Articular cartilage; Chondrocyte; De-differentiation; Monolayer expansion; Re-differentiation

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