CHARACTERISATION OF A MESENCHYMAL-LIKE STEM CELL POPULATION FROM OSTEOPHYTE TISSUE

Abstract

Bone Tissue Engineering Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4059, Australia.

Osteophytes are the most remarkable and consistently distinct feature of osteoarthritis (OA). Their formation may be related to pluripotential cells in the periosteum responding to stimulus during OA. This study aimed to isolate stem cells from osteophyte tissues, and characterise their phenotype, proliferation and differentiation potential, and immuno-modulatory properties.

Osteophyte derived cells were isolated from five osteophyte tissue samples collected during knee replacement surgery. These cells were characterised by the expression of cell surface antigens, differentiation potential into mesenchymal lineages, growth kinetics and modulation of allo-immune responses.

Multipotential stem cells (MSCs) were identified from all osteophyte samples namely osteophyte derived MSCs (oMSCs). The surface antigen expression of oMSCs was consistent with that of mesenchymal stem cells, such as lacking the haematopoietic and common leukocyte markers (CD34, CD45) while expressing those related to adhesion (CD29, CD166, CD44) and stem cells (CD90, CD105, CD73). The longevity of oMSCs in culture was superior to that of bone marrow derived MSC (bMSCs), and they readily differentiated into tissues of the mesenchymal lineages. oMSCs also demonstrated the ability to suppress allogeneic T-cell proliferation, which was associated with the expression of tryptophan degrading enzyme indoleamine 2,3 dioxygenase (IDO).

Our results showed that osteophyte derived cells had similar properties to mesenchymal stem cells in the expression of antigen phenotype, differential potential and suppression of allo-immune response. Furthermore, when compared to bMSCs, oMSCs maintained a higher proliferative capacity, which may offer an alternative source for therapeutic stem cell based tissue regeneration.