Present status of and future direction for articular cartilage repair

Abstract

Articular cartilage defects are a major clinical problem for orthopedic surgeons. About 10 years ago, autologous chondrocyte implantation (ACI) was explored [1], approved by the U.S. Food and Drug Administration (FDA), and performed in more than 20 000 patients worldwide. However, the effectiveness of ACI remains controversial because of the lack of evidence of effi cacy from randomized controlled trials. There is currently no satisfactory clinical technique that is widely accepted for the regenerative repair of these lesions. Current clinical practice usually involves a bone marrow stimulation technique, which involves subchondral bone breaking to facilitate cartilage repair from bone marrow-derived cells and cytokines. However, with this procedure, cartilage defects are repaired with fi brocartilage [2]. Almost 15 years ago, mosaicplasty [3,4] was explored in addition to ACI. Using this technique, we can repair small articular cartilage defects with hyaline cartilage, but there are still a number of problems that remain unsolved, such as donor site morbidity. In attempts to develop better methods, different cell sources and delivery vehicles, the addition of growth factors, and transduction of some genes have all been investigated. We have been interested in the use of bone marrow mesenchymal cells (BMMC) because they have a number of suitable properties [5–8]. First, it is easy to obtain autologous cells: this can be achieved by aspiration of blood from the bone marrow using local anesthesia, without major side effects. Another reason for our interest in using these cells is that because we can cause them to proliferate without their capacity for differentiation being lost, this technique can be applied in large articular cartilage defects. Therefore, this procedure can be performed clinically with relative ease. Thus, we performed BMMC transplantation in human articular cartilage defects in knee joints. In this article, we explain the articular cartilage repair procedure with cell transplantation, mainly focusing on those with BMMC transplantation.