Effect of dose and release rate of CTGF and TGFß3 on avascular meniscus healing.

Meniscus tears in the avascular region rarely functionally heal due to poor intrinsic healing capacity, frequently resulting in tear propagation, followed by meniscus deterioration. Recently, we have reported that time-controlled application of connective tissue growth factor (CTGF) and transforming tissue growth factor ß3 (TGFß3) significantly improved healing of avascular meniscus tears by inducing recruitment and step-wise fibrocartilaginous differentiation of mesenchymal stem/progenitor cells (MSCs). In this study, we investigated effects of the dose of CTGF and the release rate of TGFß3 on avascular meniscus healing in our existing explant model. Our hypothesis was that dose and release rate of CTGF and TGFß3 are contributing factors for functional outcome in avascular meniscus healing by stem cell recruitment. Low (100 ng/ml) and high (1,000 ng/ml) doses of CTGF as well as fast (0.46 ± 0.2 ng/day) and slow (0.29 ± 0.1 ng/day) release rates of TGFß3 were applied to our established meniscus explant model for meniscus tears in the inner-third avascular region. The release rate of TGFß3 was controlled by varying compositions of poly(lactic-co-glycolic acids) (PLGA) microspheres. The meniscus explants were then cultured for 8 weeks on top of mesenchymal stem/progenitor cells (MSCs). Among the tested combinations, we found that a high CTGF dose and slow TGFß3 release are most effective for integrated healing of avascular meniscus, demonstrating improvements in alignment of collagen fibers, fibrocartilaginous matrix elaboration and mechanical properties. This study may represent an important step toward the development of a regenerative therapy to improve healing of avascular meniscus tears by stem cell recruitment. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1555-1562, 2019.

The in vitro effects of CCN2 on odontoblast-like cells.

OBJECTIVE: To investigate the in vitro effects of CCN2 on odontoblast-like cells proliferation and differentiation. DESIGN: MDPC-23 cells were cultured in DMEM supplemented with 5% FBS. CCN2 was either added to culture media or coated onto culture polystyrene, addition or coating of dH2O was served as control. In the addition group, CCN2 (100 ng/mL) was added into culture media. In the coating group, CCN2 at the concentration of 1000 ng/mL was employed. Cell proliferation was performed using CCK-8 assay. Cell differentiation and mineralization were analyzed by ALPase activity assay, real time RT-PCR and alizarin red staining. One-way ANOVA with post-hoc tukey HSD test was used for statistical analysis. RESULTS: MDPC-23 cells exhibited robust proliferative activity upon exposure to either soluble or immobilized CCN2. ALP activity of cells cultured on CCN2-modified surface was continuously strengthened from day six (0.831 ±â€¯0.024 units/µg protein versus 0.563 ±â€¯0.006 units/µg protein of control) till day eight (1.035 ±â€¯0.139 units/µg protein versus 0.704 ±â€¯0.061 units/µg protein of control). Gene expression of BSP, OCN and OPN were promoted by soluble CCN2 after 48 h exposure. Moreover, gene expression of BSP, OCN, OPN, ALP, COL1 A1, Runx-2, DSPP and DMP-1 was significantly enhanced by immobilized CCN2. Finally, mineralization of MDPC-23 cells was accelerated by both soluble and immobilized CCN2 to different extent. CONCLUSIONS: The findings indicate that CCN2 promoted proliferation, odontogenic gene expression and mineralization of MDPC-23 cells. It is proposed that CCN2 may be a promising adjunctive formula for dentin regeneration.