Chondrocytes and Mesenchymal Stem Cells (MSCs) are commonly used in cartilage repair therapies, but the regenerated tissue often contains an admixture of hyaline and fibrocartilaginous tissue. Chondroprogenitor cells (CPCs), a subset of cartilage resident cells, are being investigated for their potential to produce hyaline-like repair tissue. However, identifying distinguishing markers for chondroprogenitors remains challenging due to their similarity to MSCs and their chondrogenic nature. Ghrelin, its receptor Growth Hormone Secretagogue Receptor (GHSR), and the enzyme membrane-bound Ghrelin O-Acyl Transferase (mBOAT) are implicated in chondrogenesis, with differing expression patterns in chondrocytes versus MSCs. This study examines GHSR and mBOAT as potential markers to differentiate between MSCs and cartilage resident cells. Bone marrow-derived MSCs, chondrocytes, fibronectin adhesion assay-derived CPCs (FAA-CPs), and migratory CPCs (MCPs) from osteoarthritic cartilage donors (n=3) were isolated and cultured to passage 2. Gene expression of GHSR and mBOAT was evaluated using qRT-PCR.
While all cell groups showed moderate gene expression, FAA-CPs demonstrated higher GHSR expression, and both progenitor subsets (FAA-CPCs and MCPs) exhibited higher mBOAT levels than BM-MSCs and chondrocytes. However, no significant differences were observed between the cell groups. The study suggests the potential of Ghrelin, GHSR, and mBOAT as markers for chondrogenesis. Previous findings of elevated Ghrelin levels in chondrocytes and this study’s higher GHSR and mBOAT levels in CPCs imply a complex relationship between Ghrelin signalling components and cartilage-derived cells. Further research with larger sample sizes and non-diseased cells is needed to confirm these findings and assess the utility of GHSR and mBOAT as definitive biomarkers for chondrogenesis.
