Umbilical cord-derived mesenchymal stem cell therapy for knee osteoarthritis and cartilage repair: Current evidence and clinical applications.

Osteoarthritis is fundamentally a whole-joint disease, and a critical pathological feature is the limited capacity of articular cartilage for self-regeneration, leading to accelerated joint degeneration once breakdown begins. Current therapeutic strategies are primarily palliative, and conventional marrow stimulation procedures, such as microfracture, often yield suboptimal, short-lived outcomes. Stem cell-based biologic augmentation using mesenchymal stem cells (MSCs) has emerged as a promising approach through direct chondrocyte differentiation, paracrine stimulation, and immunomodulation. Umbilical cord-derived MSCs offer a robust proliferative capacity, enhanced biological potency, and lower immunogenicity than adult MSCs, and they can be obtained with minimal ethical concerns. Clinical trials of human umbilical cord blood-derived MSCs combined with a hyaluronic acid hydrogel (CARTISTEM®) have demonstrated excellent safety, improved patient-reported outcomes, and durable hyaline-like cartilage regeneration. Emerging evidence further suggests that combining a high tibial osteotomy with a human umbilical cord blood-derived mesenchymal stem-cells-based cartilage regeneration for medial compartment osteoarthritis with varus malalignment creates a synergistic biological and mechanical environment that promotes structural cartilage repair. In conclusion, surgically transplanted human umbilical cord blood-derived MSCs show therapeutic potential in arthritic knees, although the roles of intra-articular injections and the optimal indications for combined high tibial osteotomy remain to be clarified.