Papers by Keyword: Chondrocytes

Abstract: Since articular cartilage is avascular, both nutrient supply and metabolic waste excretion depend on diffusion. However, the major cause of the progression of articular cartilage defect is the poor inherent regenerative capacity of chondrocytes which limits the process of cartilage tissue repair. Creation of nutrient gradients in in vitro cell culture, however, can provide a clue on zonal distributions of cells and glycosaminoglycan synthesis throughout the tissue engineered cartilage. We hypothesized that glucose gradient, in combination with growth factors, could induce differences in matrix distributions for articular cartilage regeneration. Chondrocytes were harvested from bovine cartilage and expanded in monolayers. First, either p0 or p2 chondrocytes were differentiated in serum-free chondrogenic medium containing different glucose concentrations supplemented with TGFβ3/dex or IGF-1under hypoxic or normoxic conditions for 7 days in monolayer. The results indicate that cellular metabolism, cell numbers and glycosaminoglycan (GAG) content increased with increase in glucose concentration in all conditions. Aggrecan (AGC) expression consistently increased with decreasing glucose concentration in both normoxic and hypoxic conditions. COL II and COL I expressions increased with increasing glucose concentration up to 5mmol/L. The expression of COMP increased with increasing glucose concentration under hypoxic conditions and interestingly showed an opposite trend under normoxic conditions. However, comparing the chondrogenic capacity of p0 and p2 cells in the different glucose concentrations did not show differences, but the potential of p2 cells was in general lower compared to p0. Hypoxia had stimulatory effects on matrix production compared to normoxia in both passages. Therefore, supplemented glucose concentration in monolayer could induce differences in matrix production, but the chondrogenic potential remained equal. Therefore, this information could be use to a create gradients through a tissue-engineered cartilage.

Abstract: In this study, the elastic parameters of rabbit chondrocytes were determined from a sphere model (SM) of micropipette aspiration, in which the relative geometry of cell-micropipette and compressibility of cells were considered. Further, the influences of geometry parameter ξ (ξ = R/a, R is the radius of the cell, and a is the inner radius of the micropipette) and Poissons ratio ν of cell on the determination of elastic modulus E and bulk modulus K were evaluated. The results indicated that ξ has marked effect on the calculation of E, whereas ν varying from 0.2~0.4 is little influential on E. However, the variations of ν can cause abrupt changes of K, which may affect the subsequently viscoelastic analysis significantly. This study may be of use for more precise analysis of mechanical behaviors of cells.

Abstract: Objective: To investigate a better method of inducing hUC-MSCs into chondrocytes in different culture system in vitro. Method: hUC-MSCs were isolated and cultured by tissue block culture, and the cells surface antigens were identified by flow cytometry, hUC-MSCs were cultured with chondrogenic media and stained with Alcian Blue. The production of matrix was estimated from the determination of hydroxyproline content and Alcian Blue method. Expressions of glycosaminoglycan (GAG), type II collagen and Sox-9 were assayed by real-time fluorescence quantitative PCR. Results: The cultured hUC-MSCs phenotype was CD105+/CD29+/CD44+/ CD31-/CD34-/ CD40-/CD45-/HLA-DR-. hUC-MSCs weakly expressed chondrocyte marker, which strongly expressed GAG and type II collagen after chondrogenic induction, and the cells were incubated in pellet culture with higher expression. Real-time PCR results demonstrated that chondrogenic induction cells were expressed GAG, type II collagen and Sox-9, and the cells were incubated in pellet culture with higher expression. Conclusion: hUC-MSCs incubated in pellet culture is more conducive to differentiate into chondrocytes than those cultured in monolayer culture system.

Abstract: In the present study, three BMP-2 (bone morphogenetic protein-2) micropatterns were produced on polystyrene (PS) surface by microcontact printing in order to investigate the effect of protein micropattern on biomaterials surface on human chondrocytes behavior. The excellent BMP-2 micropatterns from fluorescent observation were successfully obtained. Cell adhesion and immunohistochemical assay were utilized to explore cell behavior. The results indicated that the protein micropatterns have significant influence on cell adhesion, spread, alignment and protein expression. The cells preferentially adhered on protein micropattern zones. The cells tend to spread towards micropattern direction, leading to better spread. The spread cells could excreted more type II and VI collagen than that of non-spread or poor-spread cells. The results of this paper suggested that extracellular matrix (ECM) protein micropatterns can effectively regulate human chondrocytes behavior, which may be helpful for development of new cartilage tissue.

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.

Abstract: Septal cartilage is widely used for the repair of soft tissue defects in the head, neck and nose. Tissue Engineering techniques are being investigated to create cartilage in vitro by seeding appropriate cells on resorbable scaffolds. In this study, human chondrocytes were cultured on macroporous bioactive glass foam scaffolds. The aim was to investigate how Raman spectroscopy could be used as a non-invasive technique to monitor the response of chondrocytes to a 3D scaffold in real time. The spectra were compared to scanning electron microscope (SEM) micrographs and immunohistochemistry results.

Abstract: Due to its intrinsically poor repair potential, injuries to articular cartilage do not heal and clinical intervention is required. Osteochondral grafts may improve healing while promoting integration with host tissue. We report here the development of an osteochondral graft based on a hybrid of a hyrogel and a polymer-bioactive glass composite (PLAGA-BG) microsphere scaffold. This novel osteochondral construct consists of three regions: gel-only, gel/composite interface, and a composite-only-region. The three phases differ in calcium phospate (Ca-P) or BG content. The objective of the current study is to investigate the effects of scaffold composition on chondrocyte response, and to evaluate the effects of co-culture on osteoblasts and chondrocyte growh and differentiation on the hybrid scaffold. The PLAGA-BG microsphere scaffold supported the growth of chondrocytes and initial results indicate that in the presence of BG, chondrocyte-mediated mineralization may be stimulated. Co-culture of osteoblasts and chondrocytes on the multi-phased scaffold with varied Ca-P content facilitated the formation of multiple matrix zones: a GAGrich chondrocyte region, an interfacial matrix rich in GAG+collagen, and a mineralized collagen matrix with osteoblasts. In summary, chondrocyte response has been optimized as a function of scaffold composition and the novel osteochondral graft has the potential to support the simultaneous formation of multiple types of tissue in vitro.