Microencapsulated Mesenchymal Stem Cells As a Platform for Engineering an Injectable Cartilage Repair/Regeneration Strategy

Current treatments for joint deterioration due to trauma or osteoarthritis, are very invasive and typically fail to completely regenerate substantial amounts of functional tissue. Development of an injectable therapy that combines living cells and materials that direct articular cartilage matrix deposition could relieve the painful symptoms of osteoarthritis and ultimately reverse the effects of joint wear. In this study, rat bone marrow mesenchymal stem cells (MSCs), a cell type with established differentiation capacity towards a chondrogenic cell lineage, were encapsulated inside microcapsules composed of chitosan and chondroitin 4-sulfate (C4S). Chitosan and C4S have demonstrated low immunogenicity and the ability to adsorb growth factors that promote cartilage matrix synthesis by chondrocytes. The microcapsules are also injectable and Encapsulated MSCs induced to differentiate to a chondrogenic lineage, showed extensive cell aggregation and a high level of sulfated glycosaminoglycan deposition within the microcapsules. The deposited matrix exhibited staining characteristics similar to the native cartilage extracellular matrix. The results to date demonstrate an in vitro proof-of-concept for the use of MSCs for damaged articular cartilage repair via injection of encapsulated MSC-derived chondrocytes.