Recent advances in tissue engineering of cartilage, bone, and tendon

Abstract

Purpose of review: The research of tissue engineering includes the study of seed cells, biomaterials, and engineering of different tissue types in animals. Tissue construction in animals is the end point of tissue engineering research and is also an essential step towards the clinical application of engineered tissue. The purpose of this review is to summarize the advancement in cartilage, bone, and tendon engineering, particularly focusing on the area of tissue construction. Recent findings: Tremendous progress has been achieved in the areas of seed cells and biomaterials during the past 1 to 2 years. In contrast, relatively fewer papers have been published regarding the advancement in tissue construction of bone, cartilage, and tendon. In cartilage engineering, it has been reported that articular cartilage defect and meniscal defect could be repaired in immunocompetent animals by engineered cartilage using chondrocytes and biomaterials. Recent studies focused on the use of bone marrow stem cells to achieve a tissue-specific repair of osteochondral defect of the knee joint. Interestingly, there is sufficient evidence to prove that implanted stem cells can differentiate into both chondrocytes and osteoblasts in different microenvironments of the knee joint. Noticeably, significant progress was made in the engineering of cartilage in vitro using stem cells. More sophisticated studies have been performed on bone engineering when compared with cartilage engineering. Either flat bone or weight-bearing bone could be successfully generated in large animals and be used to repair cranial and alveolus bone defects, tibia and femoral bone defects. Based on sophisticated animal studies, clinical trial of engineered bone has been launched in several countries with a preliminary success, providing a promising future of clinical application. Among three tissue types, tendon engineering achieved the least progress in its tissue construction. Chicken model was successfully used to engineer a superficial flexor tendon within a tendon sheath using autologous tenocytes. Rabbit model was applied to engineer the Achilles tendon using autologous bone marrow stem cells with a success. Due to the multidifferentiation potential, more investigations preferred to use bone marrow stem cells as seed cells for engineering cartilage, bone, and tendon. An interesting finding is that adipose derived stem cells might potentially serve as another source of seed cells for the engineering of these tissues. Summary: Progress has been achieved in the tissue construction of bone, cartilage, and tendon. Successful clinical trial of engineered bone provides a promising future in clinical application of engineered tissues.