Mesenchymal Stem Cell Therapy in Cartilage Injuries of Knee – Review

Abstract

Full-thickness cartilage injuries when left alone would increase the risk of osteoarthritis (OA) with severe associated pain and functional disability. The capability of the mesenchymal stem cells (MSCs) to repair and regenerate cartilage has been widely investigated. Articular cartilage defect may result from direct trauma or chronic degeneration. The subchondral bone plays an important role in healing through the presence of mesenchymal elements. MSCs are the most representative adult stem cells. It was observed that BM-MSCs (Bone Marrow derived MSCs) had superior chondrogenic differentiation capacity as compared to MSCs from other origins. It has been observed that a MSC density of 5 × 107 or 5 × 108 cells per milliliter embedded in a collagen gel had more proteoglycans than lower cell densities, better facilitating cartilage defect healing. The most potent chondrogenic differentiation inducers are transforming growth factor β, bone morphogenic protein, fibroblast growth factor, and insulin-like growth factor 1. Most commonly used delivery system for MSCs are either sealant or scaffold based. Ideal scaffold should have similar characteristics to the native tissue. The scaffold has the advantage of withstanding the in-vivo loading environment and protects the embedded cells. There is contradictory evidence regarding injectable treatment with BM-MSCs suggesting scaffolds may be required for the regeneration of cartilage. There is high quality of evidence to support MSC therapy but further refinement of methodology will be required to support its routine clinical use. There are few options to be explored e.g. MSC exosomes, genetic engineering and epigenetic regulatory mechanisms governing MSC biology