Temporomandibular Joint Fibrocartilage Contains CD105 Positive Mouse Mesenchymal Stem/Progenitor Cells with Increased Chondrogenic Potential.

OBJECTIVE

A specific type of mesenchymal stem/progenitor cells (MSPCs), CD105 is reported to aid in cartilage regeneration through TGF-β/Smad2-signalling. The purpose of this study was to identify and characterize CD105 MSPCs in temporomandibular joint (TMJ) cartilage.

MATERIALS AND METHODS

MSPCs were isolated from mouse TMJ condyle explants and evaluated for their clonogenicity and pluripotential abilities. MSPC were examined for CD105 antigen using immunohistochemistry and flow cytometry.

RESULTS

Immunohistochemistry revealed presence of CD105 MSPCs in the proliferative zone of condyle's cartilage. Only 0.2% of isolated MSPCs exhibited CD105, along with the stem cell surface markers CD44 and Sca-1. In CD105 MSPCs, intracellular immunostaining revealed significantly higher ( < 0.05) protein levels of collagen type 1, 2, proteoglycan 4. Ability for chondrogenic differentiation was found to be significantly higher ( < 0.05) after 4 weeks compared to CD105 cells, using alcian blue staining. CD105 cells were found to resemble an early MSPC subgroup with significantly higher gene expression of biglycan, proteoglycan 4, collagen type 2, Gli2, Sox5 ( < 0.001) and Sox9 ( < 0.05). In contrast, significantly lower levels of Runx2 ( < 0.05), Osterix, Trps1, Col10a1 ( < 0.01), Ihh ( < 0.001) related to chondrocyte senescence and commitment to osteogenic lineage, were observed compared to CD105 cells.

CONCLUSION

The study showed the existence of a CD105 MSPC subgroup within TMJ fibrocartilage that may be activated to aid in fibrocartilage repair.