Intra-Articular Injection of PKH26-Labeled Mesenchymal Stem Cells (MSCs) in Treatment of Experimentally Induced Osteoarthritis

Objective: The object of this study is to detect the distribution of PKH26-labeled bone marrow derived-Mesenchymal Stem Cells (MSCs) in the articular cartilage after its intraarticular injection and to evaluate its efficacy as a treatment option of Mono-Iodoacetate (MIA) induced osteoarthritis in rat knee joint monitored by immunofluroscent microscopy and light microscopy. Material and Methods: This study was carried out on 35 adult male albino rats. They were classified into 3 groups: Group A (control group), Group B (osteoarthritic group) in which rats received lmg of MIA and sacrificed after 2 weeks and after 4 weeks and Group C (mesenchymal stem cell treated group) in which rats received PKH26-labeled MSCs 2 weeks after MIA injection or 4 weeks after MIA and sacrificed 2 weeks later. Sections were taken from rats knee joints. Detection of PKH26-labeled MSCs in unstained paraffin sections was carried out by fluorescent microscope. Other sections stained with Hematoxylin and Eosin and examined by light microscopy. The mean Articular Cartilage (AC) thickness for H E stained sections was measured using image analyzer and statistically analyzed. Results: Examination of unstained sections of Group C (MSCs treated group) with fluorescent microscope revealed yellow fluorescent MSCs labeled with PKH26 distributed at AC of both subgroups CI and subgroup C2. Stained sections of Group B showed features of osteoarthritis. Many chondrocytes showed small dark nuclei. Some chondrocytes appeared shrunken with hypereosinophilic cytoplasm. Many osteoclasts were noticed with significant reduction in cartilage thickness compared to control. Stained sections of AC in the MSCs treated group showed apparent improvement of the osteoarthritic features in the form of increase in the AC thickness with normal zonation and proliferation of chondrocytes. Conclusion: Bone marrow derived mesenchymal stem cells labeled with PKH26 (MSCs) could be detected in the articular cartilage after its injection with significant improvement of osteoarthritic features in experimentally induced osteoarthritis in rat knee joint.