Augmentation of Degenerated Human Cartilage In Vitro Using Magnetically Labeled Mesenchymal Stem Cells and an External Magnetic Device

Purpose: The purpose of this study was to investigate whether it is possible to regenerate degenerated human cartilage in vitro by use of magnetically labeled mesenchymal stem cells (MSCs) and an external magnetic device. Methods: MSCs from human bone marrow were cultured and magnetically labeled. Degenerated human cartilage was obtained during total knee arthroplasty. The osteochondral fragments were attached to the sidewall of tissue culture flasks, and magnetically labeled MSCs were injected into the flasks. By use of an external magnetic device, a magnetic force was applied for 6 hours to the direction of the cartilage, and then the degenerated cartilage was cultured in chondrogenic differentiation medium for 3 weeks. In the control group a magnetic force was not applied. The specimens were evaluated histologically. Results: A cell layer was formed on the degenerated cartilage as shown by H&E staining. The cell layer was also stained in toluidine blue and safranin O and with anti-collagen type II immunostaining, indicating that the cell layer contained an extracellular matrix. In the control group a cell layer was not observed on the cartilage. Conclusions: We were able to show that our system could deliver MSCs onto degenerated human cartilage and then form an extracellular matrix on the degenerated cartilage in vitro. Clinical Relevance: Our novel cell delivery system using magnetic force may lead toward a new treatment option for osteoarthritis.