ABSTRACT
BACKGROUND: Cartilage tissue repair is an important field of tissue engineering. How to use engineering technology to effectively differentiate seed cells into chondrocytes is a focus and difficulty in the field of tissue engineering. At present, it is difficult to make seed cells differentiate into mature and stable chondrocytes by simple orientation-inducing culture. Thereafter, the authors preliminarily studied the induced directional differentiation using intermittent hydrostatic pressure stimulation based on the characteristics of ATDC5 chondrocytes, in addition to the use of effective culture solution. OBJECTIVE: To investigate the effects of intermittent hydrostatic pressure on the earlyterm chondrocyte differentiation of ATDC5 cells. METHODS: ATDC5 cell lines were cultured in multilayer. Cells adhered well with multiple-layer formation after 3 days, and were then sealed to maintain sterility. Intermittent hydrostatic pressure was applied to the cultures (10 MPa, 1 Hz, 4 h/d). Cells cultured with no intermittent hydrostatic pressure served as control group. Morphological changes of the cells were observed under microscope at 4, 7, 11, 14, and 17 days. Expression levels of Aggrecan, COL-2 and SOX-9 mRNA were detected by real-time PCR. RESULTS AND CONCLUSION: After application of intermittent hydrostatic pressure, ATDC5 cells aggregated and appeared with obvious patchy changes. The mRNA expression levels of Aggrecan and COL-2 were significantly increased. SOX-9 mRNA expression level showed no significant difference compared with the control group, but presented with fall-rise pattern. Intermittent hydrostatic pressure influences the mRNA expression related to chondrocyte differentiation and promotes the secretion of chondrogenic matrix. This method is contributive to the mature cartilage differentiation.
ABSTRACT
Endochondral bone formation is the process by which mesenchymal cells condense into chondrocytes, which are ultimately responsible for new bone formation. The processes of chondrogenic differentiation and hypertrophy are critical for bone formation and are therefore highly regulated. The present study was designed to investigate the effect of aloe-emodin on chondrogenic differentiation in clonal mouse chondrogenic ATDC5 cells. Aloe-emodin treatment stimulated the accumulation of cartilage nodules in a dose-dependent manner. ATDC5 cells were treated with aloe-emodin and stained with alcian blue. Compared with the control cells, the ATDC5 cells showed more intense alcian blue staining. This finding suggested that aloe-emodin induced the synthesis of matrix proteoglycans and increased the activity of alkaline phosphatase. Aloe-emodin also enhanced the expressions of chondrogenic marker genes such as collagen II, collagen X, BSP and RunX2 in a time-dependent manner. Furthermore, examination of the MAPK signaling pathway showed that aloe-emodin increased the activation of extracellular signal-regulated kinase (ERK), but had no effect on p38 and c-jun N-terminal kinase (JNK). Aloe-emodin also enhanced the protein expression of BMP-2 in a time-dependent manner. Thus, these results showed that aloe-emodin exhibited chodromodulating effects via the BMP-2 or ERK signaling pathway. Aloe-emodin may have potential future applications for the treatment of growth disorders.