Isolation and Analysis of Matched Osteoarthritic Cartilage Progenitor Cells and Bone Marrow Mesenchymal Stem Cells

Osteoarthritis (OA) is a chronic degenerative disorder that impacts synovial joints, leading to the degradation of articular cartilage and alterations in bone structure. As the most prevalent type of polyarthritis, its occurrence is increasing, particularly in Western countries. Current treatment options for OA involve various pharmacological therapies and prosthetic devices, which come with numerous limitations. Consequently, there is a growing interest among both patients and health care professionals in biological therapies, particularly the use of stem and progenitor cells for cartilage regeneration.

We extract articular cartilage progenitor cells (CPCs) and bone marrow mesenchymal stem cells (MSCs) from the femoral side of the knee joint of OA patients undergoing total knee arthroplasty. To isolate CPCs, digested full-depth chondrocytes from the femoral condyle undergo a fibronectin adhesion assay, while we separate bone marrow MSCs using the Ficoll™ density gradient centrifugation method. We expand both cell types in culture and measure their growth kinetics over 80 days. Additionally, we evaluate proliferation potential and senescence through bromodeoxyuridine incorporation and the senescence-associated β-galactosidase assay, respectively. Further, we analyze the expression of specific MSC markers in articular CPCs and bone marrow MSCs using flow cytometry.  Results: We successfully isolated CPCs and bone marrow MSCs from matched osteoarthritic donors. The isolated CPCs and MSCs exhibit similar morphology and proliferation ability. Moreover, both cell types show positive expression for MSC markers CD-90, CD-105, and CD-166, while expressing low or no levels of CD-34 (a marker for hematopoietic stem cells) and exhibiting tri-lineage differentiation potential.  Conclusion: We successfully isolate CPCs and bone marrow MSCs from the knee joints of osteoarthritic donors. Our findings indicate that both cell types demonstrate comparable morphology and growth kinetics, concurrently marking for classical MSC markers and exhibiting differentiation potential. These results are promising for the field of regenerative medicine. In this study, we outline the isolation of a rare group of matching mesenchymal stem/progenitor cells collected from the articular cartilage and bone marrow of patients undergoing total knee arthroplasty. This discovery lays the groundwork for comparative analyses, in that these cell types are primary candidates for cartilage-based regenerative therapies.