Chondrocytes derived from mesenchymal stromal cells and induced pluripotent cells of patients with familial osteochondritis dissecans exhibit an endoplasmic reticulum stress response and defective matrix assembly

Maojia Xu, Eva Lena Stattin, Georgina Shaw, Dick Heinegård, Gareth Sullivan, Ian Wilmut, Alan Colman, Patrik Önnerfjord, Areej Khabut, Anders Aspberg, Peter Dockery, Timothy Hardingham, Mary Murphy, Frank Barry

Research output: Contribution to journalArticlepeer-review

16 Citations (SciVal)

Abstract

Familial osteochondritis dissecans (FOCD) is an inherited skeletal defect characterized by the development of large cartilage lesions in multiple joints, short stature, and early onset of severe osteoarthritis. It is associated with a heterozygous mutation in the ACAN gene, resulting in a Val-Met replacement in the C-type lectin domain of aggrecan. To understand the cellular pathogenesis of this condition, we studied the chondrogenic differentiation of patient bone marrow mesenchymal stromal cells (BM-MSCs). We also looked at cartilage derived from induced pluripotent stem cells (iPSCs) generated from patient fibroblasts. Our results revealed several characteristics of the differentiated chondrocytes that help to explain the disease phenotype and susceptibility to cartilage injury. First, patient chondrogenic pellets had poor structural integrity but were rich in glycosaminoglycan. Second, it was evident that large amounts of aggrecan accumulated within the endoplasmic reticulum of chondrocytes differentiated from both BM-MSCs and iPSCs. In turn, there was a marked absence of aggrecan in the extracellular matrix. Third, it was evident that matrix synthesis and assembly were globally dysregulated. These results highlight some of the abnormal aspects of chondrogenesis in these patient cells and help to explain the underlying cellular pathology. The results suggest that FOCD is a chondrocyte aggrecanosis with associated matrix dysregulation. The work provides a new in vitro model of osteoarthritis and cartilage degeneration based on the use of iPSCs and highlights how insights into disease phenotype and pathogenesis can be uncovered by studying differentiation of patient stem cells.

Original languageEnglish
Pages (from-to)1171-1181
Number of pages11
JournalStem cells translational medicine
Volume5
Issue number9
DOIs
Publication statusPublished - 2016

Subject classification (UKÄ)

  • Cell and Molecular Biology

Keywords

  • Aggrecan mutation
  • Cellular pathology
  • Endoplasmic reticulum stress
  • Familial osteochondritis dissecans
  • Induced pluripotent stem cells
  • Mesenchymal stromal cells
  • Osteoarthritis
  • Stem cell disease models

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