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Objective: To summarize the mechanism research progress of tendon-derived stem cells (TDSCs) in the reconstruction of fibrocartilage zone at bone-tendon junction (BTJ).
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Objective To observe the expression changes of inflammatory cytokines of human tendon-derived stem cells (TDSCs) under uniaxial stretching.Methods TDSCs were isolated from human gracilis tendon by collagenase digestion at very low density.Cells were detected for surface markers by flow cytometry,and tested for multi-differentiation potential in vitro.Repetitive uniaxial stretching was applied on the cells at 0％,4％,8％ or 10％ strain.Under the microscopy,cell alignment was observed after mechanical stretching.Expressions of inflammation factors COX-2 and MMP-1 were detected by qPCR and western blotting.Results TDSCs were successfully isolated from human gracilis tendon.Inflammatory cytokines CD29,CD44 and CD105 were positive,but CD45 and CD14 were negative.TDSCs could differentiate into osteocytes,adipocytes and chondrocytes in vitro.Cells were not realigned4 hours after mechanical stretching.MMP-1 mRNA expression was significantly down-regulated at 4％ strain (0.090 ± 0.007) compared to that at 0％ strain (0.247 ± 0.032,P ＜ 0.05).No significant difference was found in COX-2 mRNA expression at 4％ and 8％ strain (both was 0.005 ±0.001,P ＞0.05).MMP-1 and COX-2 mRNA expressions at 8％ strain (0.168 ± 0.040 and 0.007 ± 0.001)revealed no significant differences from those at 0％ strain (0.134 ±0.075 and 0.006 ±0.003) (P ＞0.05),whereas at 10％ strain MMP-1 and COX-2 mRNA expressions were significantly up-regulated (0.047 ± 0.003 and 0.496 ± 0.036) compared to those at 0％ strain (0.011 ± 0.003 and 0.005 ± 0.003)(P ＜ 0.05).Changes in MMP-1 and COX-2 protein expressions revealed similar trend as their mRNA expressions.In contrast to the setting of 0％ strain,4％ strain induced down-regulated MMP-1 and COX-2 proteins,8％ strain induced no significant changes in MMP-1 and COX-2 proteins,and 10％ strain induced up-regulated COX-2 protein despite minor increase in MMP-1 protein.Conclusions Mechanical stretching can affect the secretion of inflammatory cytokines.Low tensile stretch is associated with decreased expression of inflammatory cytokines while high tensile stretch promotes secretion of inflammatory cytokines.
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Objective To observe the effect of sustained release type Ⅰ collagen-vascular endothelial growth factor (VEGF) on healing of bone-tendon junction injuries.Methods Partial patellectomy was conducted in 72 rabbits divided equally into control group,type Ⅰ collagen group,and collagen type Ⅰ-VEGF group.The scaffold was planted into the bone-tendon interface.Animals were sacrificed at 4,8 and 12 weeks.New bone formation into the patella-patella tendon surface was detected using X-ray films and histological observations.Quality of bone healing was assayed using biomechanical testing.Results At postoperative 4,8 and 12 weeks,X-ray films showed bone formation of type Ⅰ collagen group [(4.1 ± 0.4) mm2,(12.1 ± 0.5) mm2,(13.0 ± 1.2) mm2 respectively] and of collagen type Ⅰ-VEGF group [(3.8 ± 0.4) mm2,(11.0 ± 0.5) mm2,(13.1 ± 1.0) mm2 respectively] were more than that of control group [(2.1 ± 0.6) mm2,(4.1 ± 0.3) mm2,(6.6 ± 0.6) mm2 respectively] (P ＜ 0.05).Histology identified few new bone,massive fibrocyte accumulation and disrupted alignment of tendon fiber in control group,massive new bone formation,neat and orderly alignment of collagen fiber tissues and massive aggrecan expression at postoperative 4 and 8 weeks (fibrous cartage repair in largely) in collagen type Ⅰ-VEGF group,and massive new bone formation but worse alignment of tendon collagen fibers and less aggrecan expression (fibrous repair in largely) in type Ⅰ collagen group.Biomechanical test showed the ultimate tensile strength increased over time in all groups,with significantly higher value at 12 weeks than that at 4 and 8 weeks.At the same time point,ultimate tensile strength ranged in an order as follows:collagen type Ⅰ-VEGF group ＞ collagen type Ⅰ group ＞ control group (P ＜ 0.05).Conclusion Sustained release type Ⅰ collagen-VEGF can accelerate early healing of bone-tendon junction injury and improve the histological and mechanical properties.
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The preparation of collagen sponges was studied in order to develop tissue engineering scaffolds. Collagen solutions with varying concentrations were obtained by condensing the initial collagen with polyethylene glycol (PEG) at 4 degrees C for different periods of time, and then were freeze-dried to make collagen scaffolds. The porous characteristics of the prepared scaffolds were characterized by use of different methods, including laser scanning confocal microscopy (LSCM), scanning electron microscopy (SEM) and tensile tests. All collagen sponges were shown to have similar interconnected porous structures but were found to have different pore size, porosity, water capacity and the mechanical property, depending on the concentration of collagen solutions. These findings indicate that the way of controlling the concentration of collagen solutions with PEG permits the freeze-drying fabrication of collagen sponges with varying porous features suitable for different tissue engineering purposes.
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Collagen , Chemistry , Freeze Drying , Polyethylene Glycols , Chemistry , Porosity , Tissue Engineering , Tissue ScaffoldsABSTRACT
[Objective]Porous collagen type Ⅱ matrices crosslinked by 1-ethyl-3-(3-dimethyl aminopropyl)carbodⅡmide(EDC) and N-hydroxysucinimide(NHS) were developed as scaffolds for cartilage tissue engineering.[Method]Collagen type Ⅱ matrix was crosslinked by EDC/NHS,and then freeze-dried to achieve collagen scaffolds.The porous characteristics of the prepared scaffolds were tested by using diffenent methods,including laser scanning confocal microscopy (LSCM),scanning electron microscopy (SEM) and mechanical testing machine.The chondrocytes labeled by GFP were planted in crosslinked collagen type Ⅱ,and observed by LSCM.[Result](1) The mechanical properties of cross-linked matrices increased significantly,reaching 2.18?0.47MPa.(2)The degradation of cross-linked matrices decreased by 8.28% after 4 hours.The pore size was about 90?m,and their average porosity and water capacity reached 93.39% and 97.78%,respectively.3.Chondrocytes were in good condition in the crosslinked collagen.[Conclusion]The present work indicates that EDC/NHS-crosslinked collagen type Ⅱ could keep the properties and biocompatibility of collagen,besides,the mechanical strength increased and the degradation was decreased.It will be suitable for cartilage tissue engineering purposes.
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Recently,tissue-engineered chondrocyte transplantation has been tried to treat full-thickness cartilage defects.Of the many scaffold materials being investigated,collagen,with good biocompatibility,biodegradable and biological activity,has been shown to have many advantageous features for the proliferation,the attachment and the differentiation.The present article reviews the applications and prospects of collagen in cartilage tissue engineering.