Differentiation potential of synovial mesenchymal stem cells isolated from hip joints affected by femoroacetabular impingement syndrome versus osteoarthritis.

We aimed to establish the characteristics of synovium-derived mesenchymal stem cells (MSCs) from the hip joints of patients with femoroacetabular impingement syndrome (FAIS) and osteoarthritis (OA), particularly their proliferation and differentiation potentials. We further investigated their functional differences.Synovium samples were harvested from 21 patients with FAIS who underwent hip arthroscopic surgery and from 14 patients with OA who underwent total hip arthroplasty. The MSC number, colony forming units, cell viability, and differentiation potential were compared. Real-time PCR assessed the differentiation potential into adipose, bone, and cartilage tissues.

The number of colonies at a density of 10⁴ at passage 0 from OA synovium was significantly higher than that from FAIS synovium (p < 0.01). However, their proliferation and viability were significantly lower than those of FAIS synovium cells (p = 0.0495). The expression of lipoprotein lipase mRNA in OA synovium cells was higher than that in FAIS synovium cells (p < 0.01). Meanwhile, the fraction of colonies positive for von Kossa and alkaline phosphatase staining, as well as the level of bone gamma-carboxyglutamate protein expression in OA synovium cells, were higher than those in FAIS synovium cells (p < 0.01). In chondrogenic pellet culture experiments, the expression of COL10A1 mRNA was lower in OA synovium than in FAIS synovium (p < 0.01).

Synovial MSCs from OA patients had greater colony numbers but less viability and proliferative potential. They also showed greater osteogenic and adipogenic potentials, whereas those from FAIS patients showed greater chondrogenic potential.