Papers by Keyword: Chondrogenesis

Abstract: Electrospun fibers have demonstrated a remarkable potential as a framework structure in the fabrication of cartilage tissue engineering (CTE) scaffolds. Various extracellular matrices have been incorporated into electrospun scaffolds to mimic and simulate the extracellular environment. The objective of this study was to fabricate hybrid constructs using composite electrospun scaffolds based on poly (ε-caprolactone) (PCL) and cartilage-derived matrix (CDM) and fibrin hydrogel to improve the viability and differentiation of human adipose-derived stromal cells (ADSCs) for CTE applications.Initially, PCL and PCL-CDM electrospun mats were fabricated. Fibrin/ ADSCs hydrogel were seeded on PCL- CDM mats and arranged layer-by-layer using sandwich technique. This method has been employed to increase cell seeding and infiltration efficiency through the entire mass of the scaffold. Real-time reverse-transcription polymerase chain reaction (RT- PCR), were performed to examine the expression of collagen types II and X, SOX9 and aggrecan. The production of glycosaminoglycan (GAG) was also tested in vitro by Toluidine blue stain and biochemical assay in the cultured scaffolds.The findings demonstrated that incorporation of CDM in PCL fibers results in improved cell viability. Hematoxylin and eosin staining showed that the sandwich method resulted in homogenous cell seeding within the scaffold. Overall, the RT- PCR, biochemical and histological results, showed that incorporation of the CDM into PCL/fibrin sandwich scaffolds stimulated ADSCs chondrogenesis and produced the products which increased expression of chondrogenic genes. It also, enhanced GAG synthesis compared to PCL/fibrin scaffolds.These findings suggest PCL-CDM/fibrin can be considered as an appropriate hybrid scaffold for CTE applications.

Abstract: We present evidences demonstrating that overexpression of IRE1a inhibits chondrocyte differentiation, as revealed by reduced expression of Col,,SOX9, ColX, MMP-13, IHH, Runx2. Furthmore, IRE1a-mediated inhibition of chondrogenesis depends on its enzymatic activity, since its point mutant lacking enzymatic activity completely loses this activity. The RNase and Kinase domains of IRE1a C-terminal is necessary for its full enzymatic activity and inhibition of chondrocyte differentiation. Mechanism studies demonstrate that granulin-epithelin precursor (GEP),a growth factor known to stimulate chondrogenesis, induced IRE1a expression in chondrogenesis. In addition, IRE1a inhibits GEP-mediated chondrocyte differentiation as a negative regulator. Altered expression of IRE1a in chondrocyte hypertrophy was accompanied by altered levels of IHH and PTHrP.Collectively,IRE1a may be a novel regulator of chondrocyte differentiation by 1) inhibition GEP-mediated chondrocyte differentiation as a negative regulator; 2) promoting IHH/PTHrP signaling.

Abstract: We previously reported that transcription factor XBP1S is upregulated during chondrocyte differentiation and demonstrates the temporal and spatial expression pattern during skeletal development. Herein, we found that XBP1S stimulates chondrocyte differentiation from mesenchymal stem cells in vitro and endochondral ossification ex vivo. In addition, XBP1S activates granulin-epithelin precursor (GEP), a growth factor known to stimulate chondrogenesis, then enhances GEP-stimulated chondrogenesis and endochondral bone formation. Collectively, these findings demonstrate that XBP1S positively regulates endochondral bone formation by activating GEP chondrogenic growth factor.

Abstract: The cartilage tissue engineering is an inspiring and profitable way for the reconstruction of cartilage defects, but it has been hampered by two large obstacles: how to get qualified seed cells and credible scaffold. This study aimed to evaluate the chondrogenic potential of rat bone marrow stromal cells (BMSCs) by loading them on alginate gel. In this study, the compounds of SD rat BMSCs and alginate gel were injected on the dorsum of rats subcutaneously. The implantations were harvested and examined by histological and immunohistochemical examination, in situ hybridization and transmission electron microscopy at different time points after the operations. The results showed that the compounds of BMSCs and alginate gel are promising for cartilage tissue engineering applications.

Abstract: Bone Marrow Stromal Cells (BMSCs) have chondrogenesis potential if chondrogenic environments or factors are provided. This study tests the hypothesis that chondrocytes can promote BMSC chondrogenesis at non-chondrogensis site. Porcine BMSCs and auricular chondrocytes were mixed at different ratios and 2.5×107 mixed cells were resuspended in 0.5 ml 30％ Pluronic, and then the mixture was injected into nude mice subcutaneously as experimental groups. Chondrocytes or BMSCs at the same cell number were mixed with 0.5 ml Pluronic and injected respectively as controls. 2.5×107 chondrocytes were mixed and injected as low concentration chondrocyte control. 8 weeks later, all specimens in experimental groups and chondrocyte group formed mature cartilage with abundant collagen II expression. Mature lacuna structures and metachromatic matrices were also observed in these specimens with the same level of GAG contents. Average wet weight of specimens in experimental groups was over 70% of that in chondrocyte group. In contrast, specimens in BMSC group showed mainly fibrous tissue. Only a small amount of cartilage was formed in specimens of low concentration chondrocyte group and the average wet weight was below 30% of that in chondrocyte group. These results demonstrate that chondrocytes can provide chondrogenic microenvironment and thus promote in vivo chondrogenesis of BMSCs at non-chondrogenesis sites. It also indicates that Pluronic is an ideal injectable biomaterial for cartilage tissue engineering.