Comparative Chondrogenic Potential of Equine Fetal Progenitor Cells and Adult Mesenchymal Stem Cells

Osteoarthritis is a major cause of lameness and morbidity in horses, dogs, and humans.  Cell-based strategies to repair joint surface lesions are generating a high level of interest, but have yet to achieve full restoration of articular cartilage structure and function. Interzone cells are synovial joint progenitor cells that exist in mammals during a short developmental window in the fetus.  Our long-term goal is to identify cells that differentiate into true articular chondrocytes and can generate normal articular cartilage.  The aim of this study is to compare the chondrogenic potential of different fetal and adult cell lines under chondrogenic induction conditions. Our hypothesis is that interzone cells have chondrogenic potential that exceeds that of adult mesenchymal stem cells. 

Cell pellets from different fetal (interzone, cartilage anlagen chondroblasts, dermal fibroblasts) and adult (bone marrow mesenchymal stem cells (MSC), adipose MSC, articular chondrocytes, dermal fibroblasts) cell lines were grown under chondrogenic induction conditions for 21 days. Histological assessment of pellets included cell morphology and matrix components determined by special stains.  Locus level and transcript isoform level gene expression are being examined using quantitative PCR and RNA-seq.

Initial experiments indicate that anlagen chondroblasts generate the largest pellets.  Histologic evaluation reveals that both interzone cells and anlagen chondroblasts produce a robust and proteoglycan-rich matrix.  Results of this study will advance our understanding of the interzone, a novel and promising developmental tissue in cell-based regenerative therapies for articular cartilage lesions.