Osteoarthritis (OA) is a highly prevalent and debilitating joint disorder characterized by the degeneration of articular cartilage. However, no effective medical therapy has been found yet due to the unclear etiology. 

A study conducted by Prof. DAI Kerong’s group provided in vivo evidence of the presence of articular cartilage stem cells (ACSCs), and disclosed the molecular mechanism of ACSCs involved in cartilage self-repair during the early osteoarthritis (OA). It’s critical to advancing the field of osteoarthritis and will compel innovation in pharmaceutical discovery and regenerative medicine. 

The graduate students, TONG Wenxue, etc., guided by Dr. ZHANG Xiaoling from Prof. DAI Kerong’s group at the Institute of Health Sciences, discovered the activated cells in the superficial zone of the articular cartilage as an attempt of cartilage self-repair. These cells which named articular cartilage stem cells (ACSCs) were isolated and proved the strong clone formation capability and multi-directional differentiation potential. The chondrogenesis capability of ACSCs was impressively greater than that of the classical bone marrow-mesenchymal stem cells (BM-MSCs). Furthermore, the inflammatory factor IL-1 inhibited the ACSCs chondrogenesis by active NF-κB signaling pathway, and the inhibitor of NF-κB pathway rescued the ACSCs chondrogenesis capability and promoted the cartilage regeneration. 

This study directly confirmed the existence of ACSCs in vivo and in situ for the first time both in normal and OA articular cartilage. Researchers also found an interesting phenomenon that ACSCs were activated and exhibited a transient proliferative response in early OA as an initial attempt for self-repair, but the active ACSCs loss gradually as the development of OA progresses.  

This research presented a potential mechanism for both cartilage intrinsic repair and its final degradation. It demonstrated the feasibility of inducing endogenous adult tissue-specific mesenchymal stem cells for articular cartilage repair and OA therapy. 

The study entitled “In Vivo Identification and Induction of Articular Cartilage Stem Cells by Inhibiting NF-κB Signaling in Osteoarthritis” was published in Stem Cells in October 2015.  

This work was supported by grants from National Natural Science Foundation of China, Chinese Academy of Sciences, and Science and Technology Commission of Shanghai Municipality, etc.