[DEVELOPMENT AND CHALLENGES OF ANNULUS FIBROSUS TISSUE ENGINEERING].

Objective: To review the biomaterial and clinical prospects of annulus tibrosus tissue engineering.
Methods: The recent literature concerning annulus fibrosus tissue engineering, including cell source, bioactive molecules, and biomaterial was extensively reviewed and summarized.
Results: Mesenchymal stem cells (MSCs) is an ideal seed cells. When annulus fibrosus cells and MSCs in the ratio of 2:1 are cultured, it shows the closest mRNA expression levels of annulus fibrosus-related markers. Bioactive molecules can be divided into 4 types: growth factors, morphogens, catabolic enzyme inhibitors, and intracellular regulators. They play an active role in promoting the synthesis of extracellular matrix, and maintaining intervertebral disc homeostasis and a balance between anabolic- and catabolic process in the disc. Based on the source, biological materials can be divided into natural materials, synthetic materials, and composite materials. The mechanical properties of the annulus fibrosus is an important basis for material design. Up to now, none of these scaffold materials is accepted as the most suitable one. The selection of scaffold materials is still to be further studied. The development of novel composite biomaterials is a trend.
Conclusion: The annulus fibrosus tissue engineering for the anulus fibrosus regeneration and repair will bring very broad prospects for clinical application in future.