The Study Of Synovial Fluid Derived Mesenchymal Stem Cells From Knee Osteoarthritis Patients

BackgroundOsteoarthritis (OA) is an extremely common joint disease worldwide. The most prominent feature of OA is the progressive destruction of articular cartilage, resulting in impaired joint motion, severe pain, and, ultimately, disability. Mesenchymal stem cells (MSCs) participate in tissue homoeostasis, remodeling, and repair. The presence of MSCs in synovial fluid (SF) and their numerically increase in early OA were reported by Jones et al. These articles are significant for their discoveries of MSCs in SF of OA knees. However, their study seemed to have some inherent limitations. Therefore, we investigate to identify SF-MSCs and compare the SF derived MSCs from different radiographic severity of knee osteoarthritis patients in terms of MSC proportion using imaging flow cytometer.MethodsCells in SF was cultured in a humidified 5% CO2 incubator at 37?. The morphology of colony-forming cells observed via microscope. After 28 days'cell proliferation, six-color flow cytometry (PE-CD44, FITC-CD90, APC-CD73, PerCP-Cy5.5-CD105, eFluor 450-CD34, APC-eFluor 780-CD45) was performed using the FlowSight(?) Imaging Flow Cytometer. Pre-operative radiographs were read to divide patients into two groups by Kellgren and Lawrence (K-L) grading. We assessed proportion and proliferating differences in MSCs harvested from knee SF from 17 early OA patients and 26 severe OA patients, then evaluated the correlation between sample MSC proportion and radiographic severity or other pre-operative characteristics.ResultsMSCs were obtained from SF with the proof of morphologic appearance and colony formation. The synovial fluid MSCs express CD44, CD90, CD73 and CD105, but lack of CD34 and CD45 expression. The mean SF-MSC proportion in the original aspirate from osteoarthritic knees of K-L grade 1 or 2 was significantly lower than that of K-L grade 3 or 4 samples (2.05% vs 3.18%, P<0.01). The proportion of MSCs in both groups is still of significant difference after culturing for 28 days (47.15% vs 57.64%, P<0.01). No correlation was seen between SF-MSC proportion and age, extent of preoperative deformity, HSS score, or body mass index. K-L grade was the only one of those factors found to have an independent effect.ConclusionsMSCs were proved to be present in human synovial fluid from knees of osteoarthritis. It would be much more accurate and distinct to identify MSCs via multi-channel image-based flow cytometry. The proportion of SF-MSCs was increased in accordance with the radiographic grading of osteoarthritis.